system/xen: XSA 206,211,212 update.

Signed-off-by: Mario Preksavec <mario@slackware.hr>

20 files changed, 2858 insertions, 1 deletions

diff --git a/system/xen/xen.SlackBuild b/system/xen/xen.SlackBuild
index fbc396f6a404..39af82975834 100644
--- a/system/xen/xen.SlackBuild
+++ b/system/xen/xen.SlackBuild
@@ -24,7 +24,7 @@
 
 PRGNAM=xen
 VERSION=${VERSION:-4.8.0}
-BUILD=${BUILD:-2}
+BUILD=${BUILD:-3}
 TAG=${TAG:-_SBo}
 
 SEABIOS=${SEABIOS:-1.10.0}
diff --git a/system/xen/xsa/xsa206-4.8-0001-xenstored-apply-a-write-transaction-rate-limit.patch b/system/xen/xsa/xsa206-4.8-0001-xenstored-apply-a-write-transaction-rate-limit.patch
new file mode 100644
index 000000000000..ee39918cb785
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0001-xenstored-apply-a-write-transaction-rate-limit.patch
@@ -0,0 +1,456 @@
+From 8b2d563e6693527e0747fbb22c5f01eeb89a6c53 Mon Sep 17 00:00:00 2001
+From: Ian Jackson <ian.jackson@eu.citrix.com>
+Date: Tue, 7 Mar 2017 16:09:12 +0000
+Subject: [PATCH 01/15] xenstored: apply a write transaction rate limit
+
+This avoids a rogue client being about to stall another client (eg the
+toolstack) indefinitely.
+
+This is XSA-206.
+
+Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
+
+Backported to 4.8 (not entirely trivial).
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: George Dunlap <george.dunlap@citrix.com>
+Acked-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
+---
+ tools/xenstore/Makefile                |   3 +-
+ tools/xenstore/xenstored_core.c        |   9 ++
+ tools/xenstore/xenstored_core.h        |   6 +
+ tools/xenstore/xenstored_domain.c      | 215 +++++++++++++++++++++++++++++++++
+ tools/xenstore/xenstored_domain.h      |  25 ++++
+ tools/xenstore/xenstored_transaction.c |   5 +
+ 6 files changed, 262 insertions(+), 1 deletion(-)
+
+diff --git a/tools/xenstore/Makefile b/tools/xenstore/Makefile
+index 36b6fd4..9cb54de 100644
+--- a/tools/xenstore/Makefile
++++ b/tools/xenstore/Makefile
+@@ -32,6 +32,7 @@ XENSTORED_OBJS_$(CONFIG_FreeBSD) = xenstored_posix.o
+ XENSTORED_OBJS_$(CONFIG_MiniOS) = xenstored_minios.o
+ 
+ XENSTORED_OBJS += $(XENSTORED_OBJS_y)
++LDLIBS_xenstored += -lrt
+ 
+ ifneq ($(XENSTORE_STATIC_CLIENTS),y)
+ LIBXENSTORE := libxenstore.so
+@@ -73,7 +74,7 @@ endif
+ $(XENSTORED_OBJS): CFLAGS += $(CFLAGS_libxengnttab)
+ 
+ xenstored: $(XENSTORED_OBJS)
+-	$(CC) $^ $(LDFLAGS) $(LDLIBS_libxenevtchn) $(LDLIBS_libxengnttab) $(LDLIBS_libxenctrl) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS)
++	$(CC) $^ $(LDFLAGS) $(LDLIBS_libxenevtchn) $(LDLIBS_libxengnttab) $(LDLIBS_libxenctrl) $(LDLIBS_xenstored) $(SOCKET_LIBS) -o $@ $(APPEND_LDFLAGS)
+ 
+ xenstored.a: $(XENSTORED_OBJS)
+ 	$(AR) cr $@ $^
+diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
+index 3df977b..d14f096 100644
+--- a/tools/xenstore/xenstored_core.c
++++ b/tools/xenstore/xenstored_core.c
+@@ -358,6 +358,7 @@ static void initialize_fds(int sock, int *p_sock_pollfd_idx,
+ 			   int *ptimeout)
+ {
+ 	struct connection *conn;
++	struct wrl_timestampt now;
+ 
+ 	if (fds)
+ 		memset(fds, 0, sizeof(struct pollfd) * current_array_size);
+@@ -377,8 +378,11 @@ static void initialize_fds(int sock, int *p_sock_pollfd_idx,
+ 		xce_pollfd_idx = set_fd(xenevtchn_fd(xce_handle),
+ 					POLLIN|POLLPRI);
+ 
++	wrl_gettime_now(&now);
++
+ 	list_for_each_entry(conn, &connections, list) {
+ 		if (conn->domain) {
++			wrl_check_timeout(conn->domain, now, ptimeout);
+ 			if (domain_can_read(conn) ||
+ 			    (domain_can_write(conn) &&
+ 			     !list_empty(&conn->out_list)))
+@@ -833,6 +837,7 @@ static void delete_node_single(struct connection *conn, struct node *node)
+ 		corrupt(conn, "Could not delete '%s'", node->name);
+ 		return;
+ 	}
++
+ 	domain_entry_dec(conn, node);
+ }
+ 
+@@ -972,6 +977,7 @@ static void do_write(struct connection *conn, struct buffered_data *in)
+ 	}
+ 
+ 	add_change_node(conn->transaction, name, false);
++	wrl_apply_debit_direct(conn);
+ 	fire_watches(conn, in, name, false);
+ 	send_ack(conn, XS_WRITE);
+ }
+@@ -1003,6 +1009,7 @@ static void do_mkdir(struct connection *conn, struct buffered_data *in)
+ 			return;
+ 		}
+ 		add_change_node(conn->transaction, name, false);
++		wrl_apply_debit_direct(conn);
+ 		fire_watches(conn, in, name, false);
+ 	}
+ 	send_ack(conn, XS_MKDIR);
+@@ -1129,6 +1136,7 @@ static void do_rm(struct connection *conn, struct buffered_data *in)
+ 
+ 	if (_rm(conn, node, name)) {
+ 		add_change_node(conn->transaction, name, true);
++		wrl_apply_debit_direct(conn);
+ 		fire_watches(conn, in, name, true);
+ 		send_ack(conn, XS_RM);
+ 	}
+@@ -1205,6 +1213,7 @@ static void do_set_perms(struct connection *conn, struct buffered_data *in)
+ 	}
+ 
+ 	add_change_node(conn->transaction, name, false);
++	wrl_apply_debit_direct(conn);
+ 	fire_watches(conn, in, name, false);
+ 	send_ack(conn, XS_SET_PERMS);
+ }
+diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h
+index ecc614f..9e9d960 100644
+--- a/tools/xenstore/xenstored_core.h
++++ b/tools/xenstore/xenstored_core.h
+@@ -33,6 +33,12 @@
+ #include "list.h"
+ #include "tdb.h"
+ 
++#define MIN(a, b) (((a) < (b))? (a) : (b))
++
++typedef int32_t wrl_creditt;
++#define WRL_CREDIT_MAX (1000*1000*1000)
++/* ^ satisfies non-overflow condition for wrl_xfer_credit */
++
+ struct buffered_data
+ {
+ 	struct list_head list;
+diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
+index 5de93d4..012dfe6 100644
+--- a/tools/xenstore/xenstored_domain.c
++++ b/tools/xenstore/xenstored_domain.c
+@@ -21,6 +21,7 @@
+ #include <unistd.h>
+ #include <stdlib.h>
+ #include <stdarg.h>
++#include <time.h>
+ 
+ #include "utils.h"
+ #include "talloc.h"
+@@ -74,6 +75,10 @@ struct domain
+ 
+ 	/* number of watch for this domain */
+ 	int nbwatch;
++
++	/* write rate limit */
++	wrl_creditt wrl_credit; /* [ -wrl_config_writecost, +_dburst ] */
++	struct wrl_timestampt wrl_timestamp;
+ };
+ 
+ static LIST_HEAD(domains);
+@@ -206,6 +211,8 @@ static int destroy_domain(void *_domain)
+ 
+ 	fire_watches(NULL, domain, "@releaseDomain", false);
+ 
++	wrl_domain_destroy(domain);
++
+ 	return 0;
+ }
+ 
+@@ -253,6 +260,9 @@ void handle_event(void)
+ bool domain_can_read(struct connection *conn)
+ {
+ 	struct xenstore_domain_interface *intf = conn->domain->interface;
++
++	if (domain_is_unprivileged(conn) && conn->domain->wrl_credit < 0)
++		return false;
+ 	return (intf->req_cons != intf->req_prod);
+ }
+ 
+@@ -284,6 +294,8 @@ static struct domain *new_domain(void *context, unsigned int domid,
+ 	domain->domid = domid;
+ 	domain->path = talloc_domain_path(domain, domid);
+ 
++	wrl_domain_new(domain);
++
+ 	list_add(&domain->list, &domains);
+ 	talloc_set_destructor(domain, destroy_domain);
+ 
+@@ -751,6 +763,209 @@ int domain_watch(struct connection *conn)
+ 		: 0;
+ }
+ 
++static wrl_creditt wrl_config_writecost      = WRL_FACTOR;
++static wrl_creditt wrl_config_rate           = WRL_RATE   * WRL_FACTOR;
++static wrl_creditt wrl_config_dburst         = WRL_DBURST * WRL_FACTOR;
++static wrl_creditt wrl_config_gburst         = WRL_GBURST * WRL_FACTOR;
++static wrl_creditt wrl_config_newdoms_dburst =
++	                         WRL_DBURST * WRL_NEWDOMS * WRL_FACTOR;
++
++long wrl_ntransactions;
++
++static long wrl_ndomains;
++static wrl_creditt wrl_reserve; /* [-wrl_config_newdoms_dburst, +_gburst ] */
++
++void wrl_gettime_now(struct wrl_timestampt *now_wt)
++{
++	struct timespec now_ts;
++	int r;
++
++	r = clock_gettime(CLOCK_MONOTONIC, &now_ts);
++	if (r)
++		barf_perror("Could not find time (clock_gettime failed)");
++
++	now_wt->sec = now_ts.tv_sec;
++	now_wt->msec = now_ts.tv_nsec / 1000000;
++}
++
++static void wrl_xfer_credit(wrl_creditt *debit,  wrl_creditt debit_floor,
++			    wrl_creditt *credit, wrl_creditt credit_ceil)
++	/*
++	 * Transfers zero or more credit from "debit" to "credit".
++	 * Transfers as much as possible while maintaining
++	 * debit >= debit_floor and credit <= credit_ceil.
++	 * (If that's violated already, does nothing.)
++	 *
++	 * Sufficient conditions to avoid overflow, either of:
++	 *  |every argument| <= 0x3fffffff
++	 *  |every argument| <= 1E9
++	 *  |every argument| <= WRL_CREDIT_MAX
++	 * (And this condition is preserved.)
++	 */
++{
++	wrl_creditt xfer = MIN( *debit      - debit_floor,
++			        credit_ceil - *credit      );
++	if (xfer > 0) {
++		*debit -= xfer;
++		*credit += xfer;
++	}
++}
++
++void wrl_domain_new(struct domain *domain)
++{
++	domain->wrl_credit = 0;
++	wrl_gettime_now(&domain->wrl_timestamp);
++	wrl_ndomains++;
++	/* Steal up to DBURST from the reserve */
++	wrl_xfer_credit(&wrl_reserve, -wrl_config_newdoms_dburst,
++			&domain->wrl_credit, wrl_config_dburst);
++}
++
++void wrl_domain_destroy(struct domain *domain)
++{
++	wrl_ndomains--;
++	/*
++	 * Don't bother recalculating domain's credit - this just
++	 * means we don't give the reserve the ending domain's credit
++	 * for time elapsed since last update.
++	 */
++	wrl_xfer_credit(&domain->wrl_credit, 0,
++			&wrl_reserve, wrl_config_dburst);
++}
++
++void wrl_credit_update(struct domain *domain, struct wrl_timestampt now)
++{
++	/*
++	 * We want to calculate
++	 *    credit += (now - timestamp) * RATE / ndoms;
++	 * But we want it to saturate, and to avoid floating point.
++	 * To avoid rounding errors from constantly adding small
++	 * amounts of credit, we only add credit for whole milliseconds.
++	 */
++	long seconds      = now.sec -  domain->wrl_timestamp.sec;
++	long milliseconds = now.msec - domain->wrl_timestamp.msec;
++	long msec;
++	int64_t denom, num;
++	wrl_creditt surplus;
++
++	seconds = MIN(seconds, 1000*1000); /* arbitrary, prevents overflow */
++	msec = seconds * 1000 + milliseconds;
++
++	if (msec < 0)
++                /* shouldn't happen with CLOCK_MONOTONIC */
++		msec = 0;
++
++	/* 32x32 -> 64 cannot overflow */
++	denom = (int64_t)msec * wrl_config_rate;
++	num  =  (int64_t)wrl_ndomains * 1000;
++	/* denom / num <= 1E6 * wrl_config_rate, so with
++	   reasonable wrl_config_rate, denom / num << 2^64 */
++
++	/* at last! */
++	domain->wrl_credit = MIN( (int64_t)domain->wrl_credit + denom / num,
++				  WRL_CREDIT_MAX );
++	/* (maybe briefly violating the DBURST cap on wrl_credit) */
++
++	/* maybe take from the reserve to make us nonnegative */
++	wrl_xfer_credit(&wrl_reserve,        0,
++			&domain->wrl_credit, 0);
++
++	/* return any surplus (over DBURST) to the reserve */
++	surplus = 0;
++	wrl_xfer_credit(&domain->wrl_credit, wrl_config_dburst,
++			&surplus,            WRL_CREDIT_MAX);
++	wrl_xfer_credit(&surplus,     0,
++			&wrl_reserve, wrl_config_gburst);
++	/* surplus is now implicitly discarded */
++
++	domain->wrl_timestamp = now;
++
++	trace("wrl: dom %4d %6ld  msec  %9ld credit   %9ld reserve"
++	      "  %9ld discard\n",
++	      domain->domid,
++	      msec,
++	      (long)domain->wrl_credit, (long)wrl_reserve,
++	      (long)surplus);
++}
++
++void wrl_check_timeout(struct domain *domain,
++		       struct wrl_timestampt now,
++		       int *ptimeout)
++{
++	uint64_t num, denom;
++	int wakeup;
++
++	wrl_credit_update(domain, now);
++
++	if (domain->wrl_credit >= 0)
++		/* not blocked */
++		return;
++
++	if (!*ptimeout)
++		/* already decided on immediate wakeup,
++		   so no need to calculate our timeout */
++		return;
++
++	/* calculate  wakeup = now + -credit / (RATE / ndoms); */
++
++	/* credit cannot go more -ve than one transaction,
++	 * so the first multiplication cannot overflow even 32-bit */
++	num   = (uint64_t)(-domain->wrl_credit * 1000) * wrl_ndomains;
++	denom = wrl_config_rate;
++
++	wakeup = MIN( num / denom /* uint64_t */, INT_MAX );
++	if (*ptimeout==-1 || wakeup < *ptimeout)
++		*ptimeout = wakeup;
++
++	trace("wrl: domain %u credit=%ld (reserve=%ld) SLEEPING for %d\n",
++	      domain->domid,
++	      (long)domain->wrl_credit, (long)wrl_reserve,
++	      wakeup);
++}
++
++void wrl_apply_debit_actual(struct domain *domain)
++{
++	struct wrl_timestampt now;
++
++	if (!domain)
++		/* sockets escape the write rate limit */
++		return;
++
++	wrl_gettime_now(&now);
++	wrl_credit_update(domain, now);
++
++	domain->wrl_credit -= wrl_config_writecost;
++	trace("wrl: domain %u credit=%ld (reserve=%ld)\n",
++	      domain->domid,
++	      (long)domain->wrl_credit, (long)wrl_reserve);
++}
++
++void wrl_apply_debit_direct(struct connection *conn)
++{
++	if (!conn)
++		/* some writes are generated internally */
++		return;
++
++	if (conn->transaction)
++		/* these are accounted for when the transaction ends */
++		return;
++
++	if (!wrl_ntransactions)
++		/* we don't conflict with anyone */
++		return;
++
++	wrl_apply_debit_actual(conn->domain);
++}
++
++void wrl_apply_debit_trans_commit(struct connection *conn)
++{
++	if (wrl_ntransactions <= 1)
++		/* our own transaction appears in the counter */
++		return;
++
++	wrl_apply_debit_actual(conn->domain);
++}
++
+ /*
+  * Local variables:
+  *  c-file-style: "linux"
+diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h
+index 2554423..cec341e 100644
+--- a/tools/xenstore/xenstored_domain.h
++++ b/tools/xenstore/xenstored_domain.h
+@@ -65,4 +65,29 @@ void domain_watch_inc(struct connection *conn);
+ void domain_watch_dec(struct connection *conn);
+ int domain_watch(struct connection *conn);
+ 
++/* Write rate limiting */
++
++#define WRL_FACTOR   1000 /* for fixed-point arithmetic */
++#define WRL_RATE      200
++#define WRL_DBURST     10
++#define WRL_GBURST   1000
++#define WRL_NEWDOMS     5
++
++struct wrl_timestampt {
++	time_t sec;
++	int msec;
++};
++
++extern long wrl_ntransactions;
++
++void wrl_gettime_now(struct wrl_timestampt *now_ts);
++void wrl_domain_new(struct domain *domain);
++void wrl_domain_destroy(struct domain *domain);
++void wrl_credit_update(struct domain *domain, struct wrl_timestampt now);
++void wrl_check_timeout(struct domain *domain,
++                       struct wrl_timestampt now,
++                       int *ptimeout);
++void wrl_apply_debit_direct(struct connection *conn);
++void wrl_apply_debit_trans_commit(struct connection *conn);
++
+ #endif /* _XENSTORED_DOMAIN_H */
+diff --git a/tools/xenstore/xenstored_transaction.c b/tools/xenstore/xenstored_transaction.c
+index 84cb0bf..5059a11 100644
+--- a/tools/xenstore/xenstored_transaction.c
++++ b/tools/xenstore/xenstored_transaction.c
+@@ -120,6 +120,7 @@ static int destroy_transaction(void *_transaction)
+ {
+ 	struct transaction *trans = _transaction;
+ 
++	wrl_ntransactions--;
+ 	trace_destroy(trans, "transaction");
+ 	if (trans->tdb)
+ 		tdb_close(trans->tdb);
+@@ -183,6 +184,7 @@ void do_transaction_start(struct connection *conn, struct buffered_data *in)
+ 	talloc_steal(conn, trans);
+ 	talloc_set_destructor(trans, destroy_transaction);
+ 	conn->transaction_started++;
++	wrl_ntransactions++;
+ 
+ 	snprintf(id_str, sizeof(id_str), "%u", trans->id);
+ 	send_reply(conn, XS_TRANSACTION_START, id_str, strlen(id_str)+1);
+@@ -218,6 +220,9 @@ void do_transaction_end(struct connection *conn, struct buffered_data *in)
+ 			send_error(conn, EAGAIN);
+ 			return;
+ 		}
++
++		wrl_apply_debit_trans_commit(conn);
++
+ 		if (!replace_tdb(trans->tdb_name, trans->tdb)) {
+ 			send_error(conn, errno);
+ 			return;
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch b/system/xen/xsa/xsa206-4.8-0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch
new file mode 100644
index 000000000000..57e1e9be9ee2
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0002-xenstored-Log-when-the-write-transaction-rate-limit-.patch
@@ -0,0 +1,113 @@
+From 6a5b012157c3dbe4bb82f2aa3d950e20cb5bf9d6 Mon Sep 17 00:00:00 2001
+From: Ian Jackson <ian.jackson@eu.citrix.com>
+Date: Tue, 7 Mar 2017 16:09:13 +0000
+Subject: [PATCH 02/15] xenstored: Log when the write transaction rate limit
+ bites
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
+---
+ tools/xenstore/xenstored_core.c   |  1 +
+ tools/xenstore/xenstored_domain.c | 25 +++++++++++++++++++++++++
+ tools/xenstore/xenstored_domain.h |  2 ++
+ 3 files changed, 28 insertions(+)
+
+diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
+index d14f096..dc9a26f 100644
+--- a/tools/xenstore/xenstored_core.c
++++ b/tools/xenstore/xenstored_core.c
+@@ -379,6 +379,7 @@ static void initialize_fds(int sock, int *p_sock_pollfd_idx,
+ 					POLLIN|POLLPRI);
+ 
+ 	wrl_gettime_now(&now);
++	wrl_log_periodic(now);
+ 
+ 	list_for_each_entry(conn, &connections, list) {
+ 		if (conn->domain) {
+diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
+index 012dfe6..fd9ca39 100644
+--- a/tools/xenstore/xenstored_domain.c
++++ b/tools/xenstore/xenstored_domain.c
+@@ -22,6 +22,7 @@
+ #include <stdlib.h>
+ #include <stdarg.h>
+ #include <time.h>
++#include <syslog.h>
+ 
+ #include "utils.h"
+ #include "talloc.h"
+@@ -79,6 +80,7 @@ struct domain
+ 	/* write rate limit */
+ 	wrl_creditt wrl_credit; /* [ -wrl_config_writecost, +_dburst ] */
+ 	struct wrl_timestampt wrl_timestamp;
++	bool wrl_delay_logged;
+ };
+ 
+ static LIST_HEAD(domains);
+@@ -774,6 +776,7 @@ long wrl_ntransactions;
+ 
+ static long wrl_ndomains;
+ static wrl_creditt wrl_reserve; /* [-wrl_config_newdoms_dburst, +_gburst ] */
++static time_t wrl_log_last_warning; /* 0: no previous warning */
+ 
+ void wrl_gettime_now(struct wrl_timestampt *now_wt)
+ {
+@@ -923,6 +926,9 @@ void wrl_check_timeout(struct domain *domain,
+ 	      wakeup);
+ }
+ 
++#define WRL_LOG(now, ...) \
++	(syslog(LOG_WARNING, "write rate limit: " __VA_ARGS__))
++
+ void wrl_apply_debit_actual(struct domain *domain)
+ {
+ 	struct wrl_timestampt now;
+@@ -938,6 +944,25 @@ void wrl_apply_debit_actual(struct domain *domain)
+ 	trace("wrl: domain %u credit=%ld (reserve=%ld)\n",
+ 	      domain->domid,
+ 	      (long)domain->wrl_credit, (long)wrl_reserve);
++
++	if (domain->wrl_credit < 0) {
++		if (!domain->wrl_delay_logged++) {
++			WRL_LOG(now, "domain %ld is affected",
++				(long)domain->domid);
++		} else if (!wrl_log_last_warning) {
++			WRL_LOG(now, "rate limiting restarts");
++		}
++		wrl_log_last_warning = now.sec;
++	}
++}
++
++void wrl_log_periodic(struct wrl_timestampt now)
++{
++	if (wrl_log_last_warning &&
++	    (now.sec - wrl_log_last_warning) > WRL_LOGEVERY) {
++		WRL_LOG(now, "not in force recently");
++		wrl_log_last_warning = 0;
++	}
+ }
+ 
+ void wrl_apply_debit_direct(struct connection *conn)
+diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h
+index cec341e..561ab5d 100644
+--- a/tools/xenstore/xenstored_domain.h
++++ b/tools/xenstore/xenstored_domain.h
+@@ -72,6 +72,7 @@ int domain_watch(struct connection *conn);
+ #define WRL_DBURST     10
+ #define WRL_GBURST   1000
+ #define WRL_NEWDOMS     5
++#define WRL_LOGEVERY  120 /* seconds */
+ 
+ struct wrl_timestampt {
+ 	time_t sec;
+@@ -87,6 +88,7 @@ void wrl_credit_update(struct domain *domain, struct wrl_timestampt now);
+ void wrl_check_timeout(struct domain *domain,
+                        struct wrl_timestampt now,
+                        int *ptimeout);
++void wrl_log_periodic(struct wrl_timestampt now);
+ void wrl_apply_debit_direct(struct connection *conn);
+ void wrl_apply_debit_trans_commit(struct connection *conn);
+ 
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0003-oxenstored-comments-explaining-some-variables.patch b/system/xen/xsa/xsa206-4.8-0003-oxenstored-comments-explaining-some-variables.patch
new file mode 100644
index 000000000000..e878a385f0ad
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0003-oxenstored-comments-explaining-some-variables.patch
@@ -0,0 +1,65 @@
+From d94645f1eb00e2703aef57cac19df9e86c54d275 Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Tue, 14 Mar 2017 12:15:52 +0000
+Subject: [PATCH 03/15] oxenstored: comments explaining some variables
+
+It took a while of reading and reasoning to work out what these are
+for, so here are comments to make life easier for everyone reading
+this code in future.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
+Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+---
+ tools/ocaml/xenstored/store.ml       |  1 +
+ tools/ocaml/xenstored/transaction.ml | 10 +++++++---
+ 2 files changed, 8 insertions(+), 3 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/store.ml b/tools/ocaml/xenstored/store.ml
+index 223ee21..9f619b8 100644
+--- a/tools/ocaml/xenstored/store.ml
++++ b/tools/ocaml/xenstored/store.ml
+@@ -211,6 +211,7 @@ let apply rnode path fct =
+ 	lookup rnode path fct
+ end
+ 
++(* The Store.t type *)
+ type t =
+ {
+ 	mutable stat_transaction_coalesce: int;
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index 6b37fc2..51d5d6a 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -69,11 +69,15 @@ let can_coalesce oldroot currentroot path =
+ 	else
+ 		false
+ 
+-type ty = No | Full of (int * Store.Node.t * Store.t)
++type ty = No | Full of (
++	int *          (* Transaction id *)
++	Store.Node.t * (* Original root *)
++	Store.t        (* A pointer to the canonical store: its root changes on each transaction-commit *)
++)
+ 
+ type t = {
+ 	ty: ty;
+-	store: Store.t;
++	store: Store.t; (* This is the store that we change in write operations. *)
+ 	quota: Quota.t;
+ 	mutable paths: (Xenbus.Xb.Op.operation * Store.Path.t) list;
+ 	mutable operations: (Packet.request * Packet.response) list;
+@@ -155,7 +159,7 @@ let commit ~con t =
+ 	let has_commited =
+ 	match t.ty with
+ 	| No                         -> true
+-	| Full (id, oldroot, cstore) ->
++	| Full (id, oldroot, cstore) ->       (* "cstore" meaning current canonical store *)
+ 		let commit_partial oldroot cstore store =
+ 			(* get the lowest path of the query and verify that it hasn't
+ 			   been modified by others transactions. *)
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0004-oxenstored-handling-of-domain-conflict-credit.patch b/system/xen/xsa/xsa206-4.8-0004-oxenstored-handling-of-domain-conflict-credit.patch
new file mode 100644
index 000000000000..63cfbaee85e2
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0004-oxenstored-handling-of-domain-conflict-credit.patch
@@ -0,0 +1,299 @@
+From 1f12baed15dc7502365afb54161827405ff24732 Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Tue, 14 Mar 2017 12:15:52 +0000
+Subject: [PATCH 04/15] oxenstored: handling of domain conflict-credit
+
+This commit gives each domain a conflict-credit variable, which will
+later be used for limiting how often a domain can cause other domain's
+transaction-commits to fail.
+
+This commit also provides functions and data for manipulating domains
+and their conflict-credit, and checking whether they have credit.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+
+---
+ tools/ocaml/xenstored/connection.ml      |   5 ++
+ tools/ocaml/xenstored/define.ml          |   3 +
+ tools/ocaml/xenstored/domain.ml          |  11 +++-
+ tools/ocaml/xenstored/domains.ml         | 103 ++++++++++++++++++++++++++++++-
+ tools/ocaml/xenstored/oxenstored.conf.in |  32 ++++++++++
+ tools/ocaml/xenstored/transaction.ml     |   2 +
+ tools/ocaml/xenstored/xenstored.ml       |   2 +
+ 7 files changed, 154 insertions(+), 4 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/connection.ml b/tools/ocaml/xenstored/connection.ml
+index 3ffd35b..a66d2f7 100644
+--- a/tools/ocaml/xenstored/connection.ml
++++ b/tools/ocaml/xenstored/connection.ml
+@@ -296,3 +296,8 @@ let debug con =
+ 	let domid = get_domstr con in
+ 	let watches = List.map (fun (path, token) -> Printf.sprintf "watch %s: %s %s\n" domid path token) (list_watches con) in
+ 	String.concat "" watches
++
++let decr_conflict_credit doms con =
++	match con.dom with
++	| None -> () (* It's a socket connection. We don't know which domain we're in, so treat it as if it's free to conflict *)
++	| Some dom -> Domains.decr_conflict_credit doms dom
+diff --git a/tools/ocaml/xenstored/define.ml b/tools/ocaml/xenstored/define.ml
+index e9d957f..816b493 100644
+--- a/tools/ocaml/xenstored/define.ml
++++ b/tools/ocaml/xenstored/define.ml
+@@ -29,6 +29,9 @@ let maxwatch = ref (50)
+ let maxtransaction = ref (20)
+ let maxrequests = ref (-1)   (* maximum requests per transaction *)
+ 
++let conflict_burst_limit = ref 5.0
++let conflict_rate_limit_is_aggregate = ref true
++
+ let domid_self = 0x7FF0
+ 
+ exception Not_a_directory of string
+diff --git a/tools/ocaml/xenstored/domain.ml b/tools/ocaml/xenstored/domain.ml
+index ab34314..e677aa3 100644
+--- a/tools/ocaml/xenstored/domain.ml
++++ b/tools/ocaml/xenstored/domain.ml
+@@ -31,8 +31,12 @@ type t =
+ 	mutable io_credit: int; (* the rounds of ring process left to do, default is 0,
+ 	                           usually set to 1 when there is work detected, could
+ 	                           also set to n to give "lazy" clients extra credit *)
++	mutable conflict_credit: float; (* Must be positive to perform writes; a commit
++	                                   that later causes conflict with another
++	                                   domain's transaction costs credit. *)
+ }
+ 
++let is_dom0 d = d.id = 0
+ let get_path dom = "/local/domain/" ^ (sprintf "%u" dom.id)
+ let get_id domain = domain.id
+ let get_interface d = d.interface
+@@ -48,6 +52,10 @@ let set_io_credit ?(n=1) domain = domain.io_credit <- max 0 n
+ let incr_io_credit domain = domain.io_credit <- domain.io_credit + 1
+ let decr_io_credit domain = domain.io_credit <- max 0 (domain.io_credit - 1)
+ 
++let is_paused_for_conflict dom = dom.conflict_credit <= 0.0
++
++let is_free_to_conflict = is_dom0
++
+ let string_of_port = function
+ | None -> "None"
+ | Some x -> string_of_int (Xeneventchn.to_int x)
+@@ -84,6 +92,5 @@ let make id mfn remote_port interface eventchn = {
+ 	port = None;
+ 	bad_client = false;
+ 	io_credit = 0;
++	conflict_credit = !Define.conflict_burst_limit;
+ }
+-
+-let is_dom0 d = d.id = 0
+diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
+index 395f3a9..3d29cc8 100644
+--- a/tools/ocaml/xenstored/domains.ml
++++ b/tools/ocaml/xenstored/domains.ml
+@@ -15,20 +15,58 @@
+  *)
+ 
+ let debug fmt = Logging.debug "domains" fmt
++let error fmt = Logging.error "domains" fmt
++let warn fmt  = Logging.warn  "domains" fmt
+ 
+ type domains = {
+ 	eventchn: Event.t;
+ 	table: (Xenctrl.domid, Domain.t) Hashtbl.t;
++
++	(* N.B. the Queue module is not thread-safe but oxenstored is single-threaded. *)
++	(* Domains queue up to regain conflict-credit; we have a queue for
++	   domains that are carrying some penalty and so are below the
++	   maximum credit, and another queue for domains that have run out of
++	   credit and so have had their access paused. *)
++	doms_conflict_paused: (Domain.t option ref) Queue.t;
++	doms_with_conflict_penalty: (Domain.t option ref) Queue.t;
++
++	(* A callback function to be called when we go from zero to one paused domain.
++	   This will be to reset the countdown until the next unit of credit is issued. *)
++	on_first_conflict_pause: unit -> unit;
++
++	(* If config is set to use individual instead of aggregate conflict-rate-limiting,
++	   we use this instead of the queues. *)
++	mutable n_paused: int;
+ }
+ 
+-let init eventchn =
+-	{ eventchn = eventchn; table = Hashtbl.create 10 }
++let init eventchn = {
++	eventchn = eventchn;
++	table = Hashtbl.create 10;
++	doms_conflict_paused = Queue.create ();
++	doms_with_conflict_penalty = Queue.create ();
++	on_first_conflict_pause = (fun () -> ()); (* Dummy value for now, pending subsequent commit. *)
++	n_paused = 0;
++}
+ let del doms id = Hashtbl.remove doms.table id
+ let exist doms id = Hashtbl.mem doms.table id
+ let find doms id = Hashtbl.find doms.table id
+ let number doms = Hashtbl.length doms.table
+ let iter doms fct = Hashtbl.iter (fun _ b -> fct b) doms.table
+ 
++(* Functions to handle queues of domains given that the domain might be deleted while in a queue. *)
++let push dom queue =
++	Queue.push (ref (Some dom)) queue
++
++let rec pop queue =
++	match !(Queue.pop queue) with
++	| None -> pop queue
++	| Some x -> x
++
++let remove_from_queue dom queue =
++	Queue.iter (fun d -> match !d with
++		| None -> ()
++		| Some x -> if x=dom then d := None) queue
++
+ let cleanup xc doms =
+ 	let notify = ref false in
+ 	let dead_dom = ref [] in
+@@ -52,6 +90,11 @@ let cleanup xc doms =
+ 		let dom = Hashtbl.find doms.table id in
+ 		Domain.close dom;
+ 		Hashtbl.remove doms.table id;
++		if dom.Domain.conflict_credit <= !Define.conflict_burst_limit
++		then (
++			remove_from_queue dom doms.doms_with_conflict_penalty;
++			if (dom.Domain.conflict_credit <= 0.) then remove_from_queue dom doms.doms_conflict_paused
++		)
+ 	) !dead_dom;
+ 	!notify, !dead_dom
+ 
+@@ -82,3 +125,59 @@ let create0 doms =
+ 	Domain.bind_interdomain dom;
+ 	Domain.notify dom;
+ 	dom
++
++let decr_conflict_credit doms dom =
++	let before = dom.Domain.conflict_credit in
++	let after = max (-1.0) (before -. 1.0) in
++	dom.Domain.conflict_credit <- after;
++	if !Define.conflict_rate_limit_is_aggregate then (
++		if before >= !Define.conflict_burst_limit
++		&& after < !Define.conflict_burst_limit
++		&& after > 0.0
++		then (
++			push dom doms.doms_with_conflict_penalty
++		) else if before > 0.0 && after <= 0.0
++		then (
++			let first_pause = Queue.is_empty doms.doms_conflict_paused in
++			push dom doms.doms_conflict_paused;
++			if first_pause then doms.on_first_conflict_pause ()
++		) else (
++			(* The queues are correct already: no further action needed. *)
++		)
++	) else if before > 0.0 && after <= 0.0 then (
++		doms.n_paused <- doms.n_paused + 1;
++		if doms.n_paused = 1 then doms.on_first_conflict_pause ()
++	)
++
++(* Give one point of credit to one domain, and update the queues appropriately. *)
++let incr_conflict_credit_from_queue doms =
++	let process_queue q requeue_test =
++		let d = pop q in
++		d.Domain.conflict_credit <- min (d.Domain.conflict_credit +. 1.0) !Define.conflict_burst_limit;
++		if requeue_test d.Domain.conflict_credit then (
++			push d q (* Make it queue up again for its next point of credit. *)
++		)
++	in
++	let paused_queue_test cred = cred <= 0.0 in
++	let penalty_queue_test cred = cred < !Define.conflict_burst_limit in
++	try process_queue doms.doms_conflict_paused paused_queue_test
++	with Queue.Empty -> (
++		try process_queue doms.doms_with_conflict_penalty penalty_queue_test
++		with Queue.Empty -> () (* Both queues are empty: nothing to do here. *)
++	)
++
++let incr_conflict_credit doms =
++	if !Define.conflict_rate_limit_is_aggregate
++	then incr_conflict_credit_from_queue doms
++	else (
++		(* Give a point of credit to every domain, subject only to the cap. *)
++		let inc dom =
++			let before = dom.Domain.conflict_credit in
++			let after = min (before +. 1.0) !Define.conflict_burst_limit in
++			dom.Domain.conflict_credit <- after;
++			if before <= 0.0 && after > 0.0
++			then doms.n_paused <- doms.n_paused - 1
++		in
++		(* Scope for optimisation (probably tiny): avoid iteration if all domains are at max credit *)
++		iter doms inc
++	)
+diff --git a/tools/ocaml/xenstored/oxenstored.conf.in b/tools/ocaml/xenstored/oxenstored.conf.in
+index 82117a9..edd4335 100644
+--- a/tools/ocaml/xenstored/oxenstored.conf.in
++++ b/tools/ocaml/xenstored/oxenstored.conf.in
+@@ -9,6 +9,38 @@ test-eagain = false
+ # Activate transaction merge support
+ merge-activate = true
+ 
++# Limits applied to domains whose writes cause other domains' transaction
++# commits to fail. Must include decimal point.
++
++# The burst limit is the number of conflicts a domain can cause to
++# fail in a short period; this value is used for both the initial and
++# the maximum value of each domain's conflict-credit, which falls by
++# one point for each conflict caused, and when it reaches zero the
++# domain's requests are ignored.
++conflict-burst-limit = 5.0
++
++# The conflict-credit is replenished over time:
++# one point is issued after each conflict-max-history-seconds, so this
++# is the minimum pause-time during which a domain will be ignored.
++# conflict-max-history-seconds = 0.05
++
++# If the conflict-rate-limit-is-aggregate flag is true then after each
++# tick one point of conflict-credit is given to just one domain: the
++# one at the front of the queue. If false, then after each tick each
++# domain gets a point of conflict-credit.
++# 
++# In environments where it is known that every transaction will
++# involve a set of nodes that is writable by at most one other domain,
++# then it is safe to set this aggregate-limit flag to false for better
++# performance. (This can be determined by considering the layout of
++# the xenstore tree and permissions, together with the content of the
++# transactions that require protection.)
++# 
++# A transaction which involves a set of nodes which can be modified by
++# multiple other domains can suffer conflicts caused by any of those
++# domains, so the flag must be set to true.
++conflict-rate-limit-is-aggregate = true
++
+ # Activate node permission system
+ perms-activate = true
+ 
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index 51d5d6a..6f758ff 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -14,6 +14,8 @@
+  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  * GNU Lesser General Public License for more details.
+  *)
++let error fmt = Logging.error "transaction" fmt
++
+ open Stdext
+ 
+ let none = 0
+diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
+index 2efcce6..20473d5 100644
+--- a/tools/ocaml/xenstored/xenstored.ml
++++ b/tools/ocaml/xenstored/xenstored.ml
+@@ -89,6 +89,8 @@ let parse_config filename =
+ 	let pidfile = ref default_pidfile in
+ 	let options = [
+ 		("merge-activate", Config.Set_bool Transaction.do_coalesce);
++		("conflict-burst-limit", Config.Set_float Define.conflict_burst_limit);
++		("conflict-rate-limit-is-aggregate", Config.Set_bool Define.conflict_rate_limit_is_aggregate);
+ 		("perms-activate", Config.Set_bool Perms.activate);
+ 		("quota-activate", Config.Set_bool Quota.activate);
+ 		("quota-maxwatch", Config.Set_int Define.maxwatch);
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0005-oxenstored-ignore-domains-with-no-conflict-credit.patch b/system/xen/xsa/xsa206-4.8-0005-oxenstored-ignore-domains-with-no-conflict-credit.patch
new file mode 100644
index 000000000000..b5f4250cdcb0
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0005-oxenstored-ignore-domains-with-no-conflict-credit.patch
@@ -0,0 +1,219 @@
+From e0f02f8fb5a5130a37bd7efdc80d7f0dd46db41e Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Tue, 14 Mar 2017 12:15:52 +0000
+Subject: [PATCH 05/15] oxenstored: ignore domains with no conflict-credit
+
+When processing connections, skip those from domains with no remaining
+conflict-credit.
+
+Also, issue a point of conflict-credit at regular intervals, the
+period being set by the configuration option "conflict-max-history-
+seconds".  When issuing conflict-credit, we give a point either to
+every domain at once (one each) or only to the single domain at the
+front of the queue, depending on the configuration option
+"conflict-rate-limit-is-aggregate".
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+---
+ tools/ocaml/xenstored/connections.ml     | 14 ++++---
+ tools/ocaml/xenstored/define.ml          |  1 +
+ tools/ocaml/xenstored/domains.ml         |  4 +-
+ tools/ocaml/xenstored/oxenstored.conf.in |  2 +-
+ tools/ocaml/xenstored/xenstored.ml       | 65 +++++++++++++++++++++++---------
+ 5 files changed, 60 insertions(+), 26 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/connections.ml b/tools/ocaml/xenstored/connections.ml
+index f9bc225..ae76928 100644
+--- a/tools/ocaml/xenstored/connections.ml
++++ b/tools/ocaml/xenstored/connections.ml
+@@ -44,12 +44,14 @@ let add_domain cons dom =
+ 	| Some p -> Hashtbl.add cons.ports p con;
+ 	| None -> ()
+ 
+-let select cons =
+-	Hashtbl.fold
+-		(fun _ con (ins, outs) ->
+-		 let fd = Connection.get_fd con in
+-		 (fd :: ins,  if Connection.has_output con then fd :: outs else outs))
+-		cons.anonymous ([], [])
++let select ?(only_if = (fun _ -> true)) cons =
++	Hashtbl.fold (fun _ con (ins, outs) ->
++		if (only_if con) then (
++			let fd = Connection.get_fd con in
++			(fd :: ins,  if Connection.has_output con then fd :: outs else outs)
++		) else (ins, outs)
++	)
++	cons.anonymous ([], [])
+ 
+ let find cons =
+ 	Hashtbl.find cons.anonymous
+diff --git a/tools/ocaml/xenstored/define.ml b/tools/ocaml/xenstored/define.ml
+index 816b493..5a604d1 100644
+--- a/tools/ocaml/xenstored/define.ml
++++ b/tools/ocaml/xenstored/define.ml
+@@ -30,6 +30,7 @@ let maxtransaction = ref (20)
+ let maxrequests = ref (-1)   (* maximum requests per transaction *)
+ 
+ let conflict_burst_limit = ref 5.0
++let conflict_max_history_seconds = ref 0.05
+ let conflict_rate_limit_is_aggregate = ref true
+ 
+ let domid_self = 0x7FF0
+diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
+index 3d29cc8..99f68c7 100644
+--- a/tools/ocaml/xenstored/domains.ml
++++ b/tools/ocaml/xenstored/domains.ml
+@@ -39,12 +39,12 @@ type domains = {
+ 	mutable n_paused: int;
+ }
+ 
+-let init eventchn = {
++let init eventchn on_first_conflict_pause = {
+ 	eventchn = eventchn;
+ 	table = Hashtbl.create 10;
+ 	doms_conflict_paused = Queue.create ();
+ 	doms_with_conflict_penalty = Queue.create ();
+-	on_first_conflict_pause = (fun () -> ()); (* Dummy value for now, pending subsequent commit. *)
++	on_first_conflict_pause = on_first_conflict_pause;
+ 	n_paused = 0;
+ }
+ let del doms id = Hashtbl.remove doms.table id
+diff --git a/tools/ocaml/xenstored/oxenstored.conf.in b/tools/ocaml/xenstored/oxenstored.conf.in
+index edd4335..536611e 100644
+--- a/tools/ocaml/xenstored/oxenstored.conf.in
++++ b/tools/ocaml/xenstored/oxenstored.conf.in
+@@ -22,7 +22,7 @@ conflict-burst-limit = 5.0
+ # The conflict-credit is replenished over time:
+ # one point is issued after each conflict-max-history-seconds, so this
+ # is the minimum pause-time during which a domain will be ignored.
+-# conflict-max-history-seconds = 0.05
++conflict-max-history-seconds = 0.05
+ 
+ # If the conflict-rate-limit-is-aggregate flag is true then after each
+ # tick one point of conflict-credit is given to just one domain: the
+diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
+index 20473d5..f562f59 100644
+--- a/tools/ocaml/xenstored/xenstored.ml
++++ b/tools/ocaml/xenstored/xenstored.ml
+@@ -53,14 +53,16 @@ let process_connection_fds store cons domains rset wset =
+ 
+ let process_domains store cons domains =
+ 	let do_io_domain domain =
+-		if not (Domain.is_bad_domain domain) then
+-			let io_credit = Domain.get_io_credit domain in
+-			if io_credit > 0 then (
+-				let con = Connections.find_domain cons (Domain.get_id domain) in
+-				Process.do_input store cons domains con;
+-				Process.do_output store cons domains con;
+-				Domain.decr_io_credit domain;
+-			) in
++		if Domain.is_bad_domain domain
++		|| Domain.get_io_credit domain <= 0
++		|| Domain.is_paused_for_conflict domain
++		then () (* nothing to do *)
++		else (
++			let con = Connections.find_domain cons (Domain.get_id domain) in
++			Process.do_input store cons domains con;
++			Process.do_output store cons domains con;
++			Domain.decr_io_credit domain
++		) in
+ 	Domains.iter domains do_io_domain
+ 
+ let sigusr1_handler store =
+@@ -90,6 +92,7 @@ let parse_config filename =
+ 	let options = [
+ 		("merge-activate", Config.Set_bool Transaction.do_coalesce);
+ 		("conflict-burst-limit", Config.Set_float Define.conflict_burst_limit);
++		("conflict-max-history-seconds", Config.Set_float Define.conflict_max_history_seconds);
+ 		("conflict-rate-limit-is-aggregate", Config.Set_bool Define.conflict_rate_limit_is_aggregate);
+ 		("perms-activate", Config.Set_bool Perms.activate);
+ 		("quota-activate", Config.Set_bool Quota.activate);
+@@ -262,7 +265,22 @@ let _ =
+ 
+ 	let store = Store.create () in
+ 	let eventchn = Event.init () in
+-	let domains = Domains.init eventchn in
++	let next_frequent_ops = ref 0. in
++	let advance_next_frequent_ops () =
++		next_frequent_ops := (Unix.gettimeofday () +. !Define.conflict_max_history_seconds)
++	in
++	let delay_next_frequent_ops_by duration =
++		next_frequent_ops := !next_frequent_ops +. duration
++	in
++	let domains = Domains.init eventchn advance_next_frequent_ops in
++
++	(* For things that need to be done periodically but more often
++	 * than the periodic_ops function *)
++	let frequent_ops () =
++		if Unix.gettimeofday () > !next_frequent_ops then (
++			Domains.incr_conflict_credit domains;
++			advance_next_frequent_ops ()
++		) in
+ 	let cons = Connections.create () in
+ 
+ 	let quit = ref false in
+@@ -394,23 +412,34 @@ let _ =
+ 			     gc.Gc.heap_words gc.Gc.heap_chunks
+ 			     gc.Gc.live_words gc.Gc.live_blocks
+ 			     gc.Gc.free_words gc.Gc.free_blocks
+-		)
+-		in
++		);
++		let elapsed = Unix.gettimeofday () -. now in
++		delay_next_frequent_ops_by elapsed
++	in
+ 
+-		let period_ops_interval = 15. in
+-		let period_start = ref 0. in
++	let period_ops_interval = 15. in
++	let period_start = ref 0. in
+ 
+ 	let main_loop () =
+-
++		let is_peaceful c =
++			match Connection.get_domain c with
++			| None -> true (* Treat socket-connections as exempt, and free to conflict. *)
++			| Some dom -> not (Domain.is_paused_for_conflict dom)
++		in
++		frequent_ops ();
+ 		let mw = Connections.has_more_work cons in
++		let peaceful_mw = List.filter is_peaceful mw in
+ 		List.iter
+ 			(fun c ->
+ 			 match Connection.get_domain c with
+ 			 | None -> () | Some d -> Domain.incr_io_credit d)
+-			mw;
++			peaceful_mw;
++		let start_time = Unix.gettimeofday () in
+ 		let timeout =
+-			if List.length mw > 0 then 0. else period_ops_interval in
+-		let inset, outset = Connections.select cons in
++			let until_next_activity = min (max 0. (!next_frequent_ops -. start_time)) period_ops_interval in
++			if peaceful_mw <> [] then 0. else until_next_activity
++		in
++		let inset, outset = Connections.select ~only_if:is_peaceful cons in
+ 		let rset, wset, _ =
+ 		try
+ 			Select.select (spec_fds @ inset) outset [] timeout
+@@ -420,6 +449,7 @@ let _ =
+ 			List.partition (fun fd -> List.mem fd spec_fds) rset in
+ 		if List.length sfds > 0 then
+ 			process_special_fds sfds;
++
+ 		if List.length cfds > 0 || List.length wset > 0 then
+ 			process_connection_fds store cons domains cfds wset;
+ 		if timeout <> 0. then (
+@@ -427,6 +457,7 @@ let _ =
+ 			if now > !period_start +. period_ops_interval then
+ 				(period_start := now; periodic_ops now)
+ 		);
++
+ 		process_domains store cons domains
+ 		in
+ 
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0006-oxenstored-add-transaction-info-relevant-to-history-.patch b/system/xen/xsa/xsa206-4.8-0006-oxenstored-add-transaction-info-relevant-to-history-.patch
new file mode 100644
index 000000000000..e9f23d62c111
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0006-oxenstored-add-transaction-info-relevant-to-history-.patch
@@ -0,0 +1,88 @@
+From eedcaba31d907b889f571113e7d9739e5ce1e9e5 Mon Sep 17 00:00:00 2001
+From: Jonathan Davies <jonathan.davies@citrix.com>
+Date: Tue, 14 Mar 2017 12:17:38 +0000
+Subject: [PATCH 06/15] oxenstored: add transaction info relevant to
+ history-tracking
+
+Specifically:
+ * retain the original store (not just the root) in full transactions
+ * store commit count at the time of the start of the transaction
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
+Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+---
+ tools/ocaml/xenstored/process.ml     |  2 +-
+ tools/ocaml/xenstored/transaction.ml | 12 ++++++++----
+ 2 files changed, 9 insertions(+), 5 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 7b60376..5f92044 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -301,7 +301,7 @@ let transaction_replay c t doms cons =
+ 	| Transaction.No ->
+ 		error "attempted to replay a non-full transaction";
+ 		false
+-	| Transaction.Full(id, oldroot, cstore) ->
++	| Transaction.Full(id, oldstore, cstore) ->
+ 		let tid = Connection.start_transaction c cstore in
+ 		let new_t = Transaction.make tid cstore in
+ 		let con = sprintf "r(%d):%s" id (Connection.get_domstr c) in
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index 6f758ff..b1791b3 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -73,12 +73,13 @@ let can_coalesce oldroot currentroot path =
+ 
+ type ty = No | Full of (
+ 	int *          (* Transaction id *)
+-	Store.Node.t * (* Original root *)
++	Store.t *      (* Original store *)
+ 	Store.t        (* A pointer to the canonical store: its root changes on each transaction-commit *)
+ )
+ 
+ type t = {
+ 	ty: ty;
++	start_count: int64;
+ 	store: Store.t; (* This is the store that we change in write operations. *)
+ 	quota: Quota.t;
+ 	mutable paths: (Xenbus.Xb.Op.operation * Store.Path.t) list;
+@@ -87,10 +88,13 @@ type t = {
+ 	mutable write_lowpath: Store.Path.t option;
+ }
+ 
++let counter = ref 0L
++
+ let make id store =
+-	let ty = if id = none then No else Full(id, Store.get_root store, store) in
++	let ty = if id = none then No else Full(id, Store.copy store, store) in
+ 	{
+ 		ty = ty;
++		start_count = !counter;
+ 		store = if id = none then store else Store.copy store;
+ 		quota = Quota.copy store.Store.quota;
+ 		paths = [];
+@@ -161,7 +165,7 @@ let commit ~con t =
+ 	let has_commited =
+ 	match t.ty with
+ 	| No                         -> true
+-	| Full (id, oldroot, cstore) ->       (* "cstore" meaning current canonical store *)
++	| Full (id, oldstore, cstore) ->       (* "cstore" meaning current canonical store *)
+ 		let commit_partial oldroot cstore store =
+ 			(* get the lowest path of the query and verify that it hasn't
+ 			   been modified by others transactions. *)
+@@ -204,7 +208,7 @@ let commit ~con t =
+ 		if !test_eagain && Random.int 3 = 0 then
+ 			false
+ 		else
+-			try_commit oldroot cstore t.store
++			try_commit (Store.get_root oldstore) cstore t.store
+ 		in
+ 	if has_commited && has_write_ops then
+ 		Disk.write t.store;
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0007-oxenstored-support-commit-history-tracking.patch b/system/xen/xsa/xsa206-4.8-0007-oxenstored-support-commit-history-tracking.patch
new file mode 100644
index 000000000000..d8fadaa7496c
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0007-oxenstored-support-commit-history-tracking.patch
@@ -0,0 +1,153 @@
+From 5df600ee06458eebf037f6bff663b0a9273e3a3f Mon Sep 17 00:00:00 2001
+From: Jonathan Davies <jonathan.davies@citrix.com>
+Date: Tue, 14 Mar 2017 13:20:07 +0000
+Subject: [PATCH 07/15] oxenstored: support commit history tracking
+
+Add ability to track xenstore tree operations -- either non-transactional
+operations or committed transactions.
+
+For now, the call to actually retain commits is commented out because history
+can grow without bound.
+
+For now, we call record_commit for all non-transactional operations. A
+subsequent patch will make it retain only the ones with side-effects.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+
+---
+ tools/ocaml/xenstored/Makefile     |  1 +
+ tools/ocaml/xenstored/history.ml   | 43 ++++++++++++++++++++++++++++++++++++++
+ tools/ocaml/xenstored/process.ml   | 24 +++++++++++++++++++--
+ tools/ocaml/xenstored/xenstored.ml |  1 +
+ 4 files changed, 67 insertions(+), 2 deletions(-)
+ create mode 100644 tools/ocaml/xenstored/history.ml
+
+diff --git a/tools/ocaml/xenstored/Makefile b/tools/ocaml/xenstored/Makefile
+index 1769e55..d238836 100644
+--- a/tools/ocaml/xenstored/Makefile
++++ b/tools/ocaml/xenstored/Makefile
+@@ -53,6 +53,7 @@ OBJS = paths \
+ 	domains \
+ 	connection \
+ 	connections \
++	history \
+ 	parse_arg \
+ 	process \
+ 	xenstored
+diff --git a/tools/ocaml/xenstored/history.ml b/tools/ocaml/xenstored/history.ml
+new file mode 100644
+index 0000000..e4b4d70
+--- /dev/null
++++ b/tools/ocaml/xenstored/history.ml
+@@ -0,0 +1,43 @@
++(*
++ * Copyright (c) 2017 Citrix Systems Ltd.
++ *
++ * This program is free software; you can redistribute it and/or modify
++ * it under the terms of the GNU Lesser General Public License as published
++ * by the Free Software Foundation; version 2.1 only. with the special
++ * exception on linking described in file LICENSE.
++ *
++ * This program is distributed in the hope that it will be useful,
++ * but WITHOUT ANY WARRANTY; without even the implied warranty of
++ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
++ * GNU Lesser General Public License for more details.
++ *)
++
++type history_record = {
++	con: Connection.t;   (* connection that made a change *)
++	tid: int;            (* transaction id of the change (may be Transaction.none) *)
++	before: Store.t;     (* the store before the change *)
++	after: Store.t;      (* the store after the change *)
++	finish_count: int64; (* the commit-count at which the transaction finished *)
++}
++
++let history : history_record list ref = ref []
++
++(* Called from periodic_ops to ensure we don't discard symbols that are still needed. *)
++(* There is scope for optimisation here, since in consecutive commits one commit's `after`
++ * is the same thing as the next commit's `before`, but not all commits in history are
++ * consecutive. *)
++let mark_symbols () =
++	(* There are gaps where dom0's commits are missing. Otherwise we could assume that
++	 * each element's `before` is the same thing as the next element's `after`
++	 * since the next element is the previous commit *)
++	List.iter (fun hist_rec ->
++			Store.mark_symbols hist_rec.before;
++			Store.mark_symbols hist_rec.after;
++		)
++		!history
++
++let push (x: history_record) =
++	let dom = x.con.Connection.dom in
++	match dom with
++	| None -> () (* treat socket connections as always free to conflict *)
++	| Some d -> if not (Domain.is_free_to_conflict d) then history := x :: !history
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 5f92044..964c044 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -293,6 +293,16 @@ let write_response_log ~ty ~tid ~con ~response =
+ 	| Packet.Reply x -> write_answer_log ~ty ~tid ~con ~data:x
+ 	| Packet.Error e -> write_answer_log ~ty:(Xenbus.Xb.Op.Error) ~tid ~con ~data:e
+ 
++let record_commit ~con ~tid ~before ~after =
++	let inc r = r := Int64.add 1L !r in
++	let finish_count = inc Transaction.counter; !Transaction.counter in
++	(* This call would leak memory if historic activity is retained forever
++	   so can only be uncommented if history is guaranteed not to grow
++	   unboundedly.
++	History.push {History.con=con; tid=tid; before=before; after=after; finish_count=finish_count}
++	*)
++	()
++
+ (* Replay a stored transaction against a fresh store, check the responses are
+    all equivalent: if so, commit the transaction. Otherwise send the abort to
+    the client. *)
+@@ -363,8 +373,14 @@ let do_transaction_end con t domains cons data =
+ 		Connection.end_transaction con (Transaction.get_id t) commit in
+ 	if not success then
+ 		raise Transaction_again;
+-	if commit then
+-		process_watch (List.rev (Transaction.get_paths t)) cons
++	if commit then begin
++		process_watch (List.rev (Transaction.get_paths t)) cons;
++		match t.Transaction.ty with
++		| Transaction.No ->
++			() (* no need to record anything *)
++		| Transaction.Full(id, oldstore, cstore) ->
++			record_commit ~con ~tid:id ~before:oldstore ~after:cstore
++	end
+ 
+ let do_introduce con t domains cons data =
+ 	if not (Connection.is_dom0 con)
+@@ -448,7 +464,11 @@ let process_packet ~store ~cons ~doms ~con ~req =
+ 			else
+ 				Connection.get_transaction con tid
+ 			in
++
++		let before = Store.copy store in
+ 		let response = input_handle_error ~cons ~doms ~fct ~con ~t ~req in
++		let after = Store.copy store in
++		if tid = Transaction.none then record_commit ~con ~tid ~before ~after;
+ 
+ 		let response = try
+ 			if tid <> Transaction.none then
+diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
+index f562f59..d5c50fd 100644
+--- a/tools/ocaml/xenstored/xenstored.ml
++++ b/tools/ocaml/xenstored/xenstored.ml
+@@ -385,6 +385,7 @@ let _ =
+ 			Symbol.mark_all_as_unused ();
+ 			Store.mark_symbols store;
+ 			Connections.iter cons Connection.mark_symbols;
++			History.mark_symbols ();
+ 			Symbol.garbage ()
+ 		end;
+ 
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0008-oxenstored-only-record-operations-with-side-effects-.patch b/system/xen/xsa/xsa206-4.8-0008-oxenstored-only-record-operations-with-side-effects-.patch
new file mode 100644
index 000000000000..e3de40429801
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0008-oxenstored-only-record-operations-with-side-effects-.patch
@@ -0,0 +1,85 @@
+From f8083d52b6314f92718316f160eea47fef47988e Mon Sep 17 00:00:00 2001
+From: Jonathan Davies <jonathan.davies@citrix.com>
+Date: Thu, 23 Mar 2017 14:20:33 +0000
+Subject: [PATCH 08/15] oxenstored: only record operations with side-effects in
+ history
+
+There is no need to record "read" operations as they will never cause another
+transaction to fail.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
+
+---
+ tools/ocaml/xenstored/process.ml | 47 ++++++++++++++++++++++++++++++++++++----
+ 1 file changed, 43 insertions(+), 4 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 964c044..b435a4a 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -450,6 +450,37 @@ let function_of_type ty =
+ 	| _                              -> function_of_type_simple_op ty
+ 
+ (**
++ * Determines which individual (non-transactional) operations we want to retain.
++ * We only want to retain operations that have side-effects in the store since
++ * these can be the cause of transactions failing.
++ *)
++let retain_op_in_history ty =
++	match ty with
++	| Xenbus.Xb.Op.Write
++	| Xenbus.Xb.Op.Mkdir
++	| Xenbus.Xb.Op.Rm
++	| Xenbus.Xb.Op.Setperms          -> true
++	| Xenbus.Xb.Op.Debug
++	| Xenbus.Xb.Op.Directory
++	| Xenbus.Xb.Op.Read
++	| Xenbus.Xb.Op.Getperms
++	| Xenbus.Xb.Op.Watch
++	| Xenbus.Xb.Op.Unwatch
++	| Xenbus.Xb.Op.Transaction_start
++	| Xenbus.Xb.Op.Transaction_end
++	| Xenbus.Xb.Op.Introduce
++	| Xenbus.Xb.Op.Release
++	| Xenbus.Xb.Op.Getdomainpath
++	| Xenbus.Xb.Op.Watchevent
++	| Xenbus.Xb.Op.Error
++	| Xenbus.Xb.Op.Isintroduced
++	| Xenbus.Xb.Op.Resume
++	| Xenbus.Xb.Op.Set_target
++	| Xenbus.Xb.Op.Restrict
++	| Xenbus.Xb.Op.Reset_watches
++	| Xenbus.Xb.Op.Invalid           -> false
++
++(**
+  * Nothrow guarantee.
+  *)
+ let process_packet ~store ~cons ~doms ~con ~req =
+@@ -465,10 +496,18 @@ let process_packet ~store ~cons ~doms ~con ~req =
+ 				Connection.get_transaction con tid
+ 			in
+ 
+-		let before = Store.copy store in
+-		let response = input_handle_error ~cons ~doms ~fct ~con ~t ~req in
+-		let after = Store.copy store in
+-		if tid = Transaction.none then record_commit ~con ~tid ~before ~after;
++		let execute () = input_handle_error ~cons ~doms ~fct ~con ~t ~req in
++
++		let response =
++			(* Note that transactions are recorded in history separately. *)
++			if tid = Transaction.none && retain_op_in_history ty then begin
++				let before = Store.copy store in
++				let response = execute () in
++				let after = Store.copy store in
++				record_commit ~con ~tid ~before ~after;
++				response
++			end else execute ()
++		in
+ 
+ 		let response = try
+ 			if tid <> Transaction.none then
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0009-oxenstored-discard-old-commit-history-on-txn-end.patch b/system/xen/xsa/xsa206-4.8-0009-oxenstored-discard-old-commit-history-on-txn-end.patch
new file mode 100644
index 000000000000..f1734c8375cd
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0009-oxenstored-discard-old-commit-history-on-txn-end.patch
@@ -0,0 +1,141 @@
+From 66bdbbc41a45d2bf59ddb4ff26c52c1cc546f720 Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Thu, 23 Mar 2017 14:25:16 +0000
+Subject: [PATCH 09/15] oxenstored: discard old commit-history on txn end
+
+The history of commits is to be used for working out which historical
+commit(s) (including atomic writes) caused conflicts with a
+currently-failing commit of a transaction. Any commit that was made
+before the current transaction started cannot be relevant. Therefore
+we never need to keep history from before the start of the
+longest-running transaction that is open at any given time: whenever a
+transaction ends (with or without a commit) then if it was the
+longest-running open transaction we can delete history up until start
+of the the next-longest-running open transaction.
+
+Some transactions might stay open for a very long time, so if any
+transaction exceeds conflict_max_history_seconds then we remove it
+from consideration in this context, and will not guarantee to keep
+remembering about historical commits made during such a transaction.
+
+We implement this by keeping a list of all open transactions that have
+not been open too long. When a transaction ends, we remove it from the
+list, along with any that have been open longer than the maximum; then
+we delete any history from before the start of the longest-running
+transaction remaining in the list.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+---
+ tools/ocaml/xenstored/history.ml     | 17 +++++++++++++++++
+ tools/ocaml/xenstored/process.ml     |  4 ++--
+ tools/ocaml/xenstored/transaction.ml | 29 +++++++++++++++++++++++++----
+ 3 files changed, 44 insertions(+), 6 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/history.ml b/tools/ocaml/xenstored/history.ml
+index e4b4d70..6f7a282 100644
+--- a/tools/ocaml/xenstored/history.ml
++++ b/tools/ocaml/xenstored/history.ml
+@@ -36,6 +36,23 @@ let mark_symbols () =
+ 		)
+ 		!history
+ 
++(* Keep only enough commit-history to protect the running transactions that we are still tracking *)
++(* There is scope for optimisation here, replacing List.filter with something more efficient,
++ * probably on a different list-like structure. *)
++let trim () =
++	history := match Transaction.oldest_short_running_transaction () with
++	| None -> [] (* We have no open transaction, so no history is needed *)
++	| Some (_, txn) -> (
++		(* keep records with finish_count recent enough to be relevant *)
++		List.filter (fun r -> r.finish_count > txn.Transaction.start_count) !history
++	)
++
++let end_transaction txn con tid commit =
++	let success = Connection.end_transaction con tid commit in
++	Transaction.end_transaction txn;
++	trim ();
++	success
++
+ let push (x: history_record) =
+ 	let dom = x.con.Connection.dom in
+ 	match dom with
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index b435a4a..6f4d118 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -313,7 +313,7 @@ let transaction_replay c t doms cons =
+ 		false
+ 	| Transaction.Full(id, oldstore, cstore) ->
+ 		let tid = Connection.start_transaction c cstore in
+-		let new_t = Transaction.make tid cstore in
++		let new_t = Transaction.make ~internal:true tid cstore in
+ 		let con = sprintf "r(%d):%s" id (Connection.get_domstr c) in
+ 		let perform_exn (request, response) =
+ 			write_access_log ~ty:request.Packet.ty ~tid ~con ~data:request.Packet.data;
+@@ -370,7 +370,7 @@ let do_transaction_end con t domains cons data =
+ 		in
+ 	let success =
+ 		let commit = if commit then Some (fun con trans -> transaction_replay con trans domains cons) else None in
+-		Connection.end_transaction con (Transaction.get_id t) commit in
++		History.end_transaction t con (Transaction.get_id t) commit in
+ 	if not success then
+ 		raise Transaction_again;
+ 	if commit then begin
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index b1791b3..edd1178 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -87,12 +87,29 @@ type t = {
+ 	mutable read_lowpath: Store.Path.t option;
+ 	mutable write_lowpath: Store.Path.t option;
+ }
++let get_id t = match t.ty with No -> none | Full (id, _, _) -> id
+ 
+ let counter = ref 0L
+ 
+-let make id store =
++(* Scope for optimisation: different data-structure and functions to search/filter it *)
++let short_running_txns = ref []
++
++let oldest_short_running_transaction () =
++	let rec last = function
++		| [] -> None
++		| [x] -> Some x
++		| x :: xs -> last xs
++	in last !short_running_txns
++
++let end_transaction txn =
++	let cutoff = Unix.gettimeofday () -. !Define.conflict_max_history_seconds in
++	short_running_txns := List.filter
++		(function (start_time, tx) -> start_time >= cutoff && tx != txn)
++		!short_running_txns
++
++let make ?(internal=false) id store =
+ 	let ty = if id = none then No else Full(id, Store.copy store, store) in
+-	{
++	let txn = {
+ 		ty = ty;
+ 		start_count = !counter;
+ 		store = if id = none then store else Store.copy store;
+@@ -101,9 +118,13 @@ let make id store =
+ 		operations = [];
+ 		read_lowpath = None;
+ 		write_lowpath = None;
+-	}
++	} in
++	if id <> none && not internal then (
++		let now = Unix.gettimeofday () in
++		short_running_txns := (now, txn) :: !short_running_txns
++	);
++	txn
+ 
+-let get_id t = match t.ty with No -> none | Full (id, _, _) -> id
+ let get_store t = t.store
+ let get_paths t = t.paths
+ 
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0010-oxenstored-track-commit-history.patch b/system/xen/xsa/xsa206-4.8-0010-oxenstored-track-commit-history.patch
new file mode 100644
index 000000000000..f5d85367eb16
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0010-oxenstored-track-commit-history.patch
@@ -0,0 +1,35 @@
+From 2e94c635a652a575cb1f25f7dc5bc0ebcdbedcc4 Mon Sep 17 00:00:00 2001
+From: Jonathan Davies <jonathan.davies@citrix.com>
+Date: Mon, 27 Mar 2017 08:58:29 +0000
+Subject: [PATCH 10/15] oxenstored: track commit history
+
+Since the list of historic activity cannot grow without bound, it is safe to use
+this to track commits.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
+Reviewed-by: Thomas Sanders <thomas.sanders@citrix.com>
+---
+ tools/ocaml/xenstored/process.ml | 5 -----
+ 1 file changed, 5 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 6f4d118..1ed1a8f 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -296,12 +296,7 @@ let write_response_log ~ty ~tid ~con ~response =
+ let record_commit ~con ~tid ~before ~after =
+ 	let inc r = r := Int64.add 1L !r in
+ 	let finish_count = inc Transaction.counter; !Transaction.counter in
+-	(* This call would leak memory if historic activity is retained forever
+-	   so can only be uncommented if history is guaranteed not to grow
+-	   unboundedly.
+ 	History.push {History.con=con; tid=tid; before=before; after=after; finish_count=finish_count}
+-	*)
+-	()
+ 
+ (* Replay a stored transaction against a fresh store, check the responses are
+    all equivalent: if so, commit the transaction. Otherwise send the abort to
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch b/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch
new file mode 100644
index 000000000000..b0a8e011ee7d
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0011-oxenstored-blame-the-connection-that-caused-a-transa.patch
@@ -0,0 +1,137 @@
+From 0972f3e46001e9b3192786033663ef4ee423f8be Mon Sep 17 00:00:00 2001
+From: Jonathan Davies <jonathan.davies@citrix.com>
+Date: Thu, 23 Mar 2017 14:28:16 +0000
+Subject: [PATCH 11/15] oxenstored: blame the connection that caused a
+ transaction conflict
+
+Blame each connection found to have made a commit that would cause this
+transaction to fail. Each blamed connection is penalised by having its
+conflict-credit decremented.
+
+Note the change in semantics for the replay function: we no longer stop after
+finding the first operation that can't be replayed. This allows us to identify
+all operations that conflicted with this transaction, not just the one that
+conflicted first.
+
+Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+v1 Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
+
+Changes since v1:
+ * use correct log levels for informational messages
+Changes since v2:
+ * fix the blame algorithm and improve logging
+   (fix was reviewed by Jonathan Davies)
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+---
+ tools/ocaml/xenstored/history.ml | 12 ++++++++++
+ tools/ocaml/xenstored/process.ml | 50 ++++++++++++++++++++++++++++++++--------
+ 2 files changed, 52 insertions(+), 10 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/history.ml b/tools/ocaml/xenstored/history.ml
+index 6f7a282..e941e2b 100644
+--- a/tools/ocaml/xenstored/history.ml
++++ b/tools/ocaml/xenstored/history.ml
+@@ -58,3 +58,15 @@ let push (x: history_record) =
+ 	match dom with
+ 	| None -> () (* treat socket connections as always free to conflict *)
+ 	| Some d -> if not (Domain.is_free_to_conflict d) then history := x :: !history
++
++(* Find the connections from records since commit-count [since] for which [f record] returns [true] *)
++let filter_connections ~since ~f =
++	(* The "mem" call is an optimisation, to avoid calling f if we have picked con already. *)
++	(* Using a hash table rather than a list is to optimise the "mem" call. *)
++	List.fold_left (fun acc hist_rec ->
++		if hist_rec.finish_count > since
++		&& not (Hashtbl.mem acc hist_rec.con)
++		&& f hist_rec
++		then Hashtbl.replace acc hist_rec.con ();
++		acc
++	) (Hashtbl.create 1023) !history
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 1ed1a8f..5e5a1ab 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -16,6 +16,7 @@
+ 
+ let error fmt = Logging.error "process" fmt
+ let info fmt = Logging.info "process" fmt
++let debug fmt = Logging.debug "process" fmt
+ 
+ open Printf
+ open Stdext
+@@ -25,6 +26,7 @@ exception Transaction_nested
+ exception Domain_not_match
+ exception Invalid_Cmd_Args
+ 
++(* This controls the do_debug fn in this module, not the debug logging-function. *)
+ let allow_debug = ref false
+ 
+ let c_int_of_string s =
+@@ -308,23 +310,51 @@ let transaction_replay c t doms cons =
+ 		false
+ 	| Transaction.Full(id, oldstore, cstore) ->
+ 		let tid = Connection.start_transaction c cstore in
+-		let new_t = Transaction.make ~internal:true tid cstore in
++		let replay_t = Transaction.make ~internal:true tid cstore in
+ 		let con = sprintf "r(%d):%s" id (Connection.get_domstr c) in
+-		let perform_exn (request, response) =
+-			write_access_log ~ty:request.Packet.ty ~tid ~con ~data:request.Packet.data;
++
++		let perform_exn ~wlog txn (request, response) =
++			if wlog then write_access_log ~ty:request.Packet.ty ~tid ~con ~data:request.Packet.data;
+ 			let fct = function_of_type_simple_op request.Packet.ty in
+-			let response' = input_handle_error ~cons ~doms ~fct ~con:c ~t:new_t ~req:request in
+-			write_response_log ~ty:request.Packet.ty ~tid ~con ~response:response';
+-			if not(Packet.response_equal response response') then raise Transaction_again in
++			let response' = input_handle_error ~cons ~doms ~fct ~con:c ~t:txn ~req:request in
++			if wlog then write_response_log ~ty:request.Packet.ty ~tid ~con ~response:response';
++			if not(Packet.response_equal response response') then raise Transaction_again
++		in
+ 		finally
+ 		(fun () ->
+ 			try
+ 				Logging.start_transaction ~con ~tid;
+-				List.iter perform_exn (Transaction.get_operations t);
+-				Logging.end_transaction ~con ~tid;
++				List.iter (perform_exn ~wlog:true replay_t) (Transaction.get_operations t); (* May throw EAGAIN *)
+ 
+-				Transaction.commit ~con new_t
+-			with e ->
++				Logging.end_transaction ~con ~tid;
++				Transaction.commit ~con replay_t
++			with
++			| Transaction_again -> (
++				let victim_domstr = Connection.get_domstr c in
++				debug "Apportioning blame for EAGAIN in txn %d, domain=%s" id victim_domstr;
++				let punish guilty_con =
++					debug "Blaming domain %s for conflict with domain %s txn %d"
++						(Connection.get_domstr guilty_con) victim_domstr id;
++					Connection.decr_conflict_credit doms guilty_con
++				in
++				let judge_and_sentence hist_rec = (
++					let can_apply_on store = (
++						let store = Store.copy store in
++						let trial_t = Transaction.make ~internal:true Transaction.none store in
++						try List.iter (perform_exn ~wlog:false trial_t) (Transaction.get_operations t);
++							true
++						with Transaction_again -> false
++					) in
++					if can_apply_on hist_rec.History.before
++					&& not (can_apply_on hist_rec.History.after)
++					then (punish hist_rec.History.con; true)
++					else false
++				) in
++				let guilty_cons = History.filter_connections ~since:t.Transaction.start_count ~f:judge_and_sentence in
++				if Hashtbl.length guilty_cons = 0 then debug "Found no culprit for conflict in %s: must be self or not in history." con;
++				false
++			)
++			| e ->
+ 				info "transaction_replay %d caught: %s" tid (Printexc.to_string e);
+ 				false
+ 			)
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0012-oxenstored-allow-self-conflicts.patch b/system/xen/xsa/xsa206-4.8-0012-oxenstored-allow-self-conflicts.patch
new file mode 100644
index 000000000000..4a46db4c1448
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0012-oxenstored-allow-self-conflicts.patch
@@ -0,0 +1,58 @@
+From d3a8b4ffde38f01aa7f497d07404478b6f90041c Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Thu, 23 Mar 2017 19:06:54 +0000
+Subject: [PATCH 12/15] oxenstored: allow self-conflicts
+
+We already avoid inter-domain conflicts but now allow intra-domain
+conflicts.  Although there are no known practical examples of a domain
+that might perform operations that conflict with its own transactions,
+this is conceivable, so here we avoid changing those semantics
+unnecessarily.
+
+When a transaction commit fails with a conflict and we look through
+the history of commits to see which connection(s) to blame, ignore
+historical commits that were made by the same connection as the
+failing commit.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+---
+ tools/ocaml/xenstored/history.ml | 3 ++-
+ tools/ocaml/xenstored/process.ml | 2 +-
+ 2 files changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/history.ml b/tools/ocaml/xenstored/history.ml
+index e941e2b..4079588 100644
+--- a/tools/ocaml/xenstored/history.ml
++++ b/tools/ocaml/xenstored/history.ml
+@@ -60,11 +60,12 @@ let push (x: history_record) =
+ 	| Some d -> if not (Domain.is_free_to_conflict d) then history := x :: !history
+ 
+ (* Find the connections from records since commit-count [since] for which [f record] returns [true] *)
+-let filter_connections ~since ~f =
++let filter_connections ~ignore ~since ~f =
+ 	(* The "mem" call is an optimisation, to avoid calling f if we have picked con already. *)
+ 	(* Using a hash table rather than a list is to optimise the "mem" call. *)
+ 	List.fold_left (fun acc hist_rec ->
+ 		if hist_rec.finish_count > since
++		&& not (hist_rec.con == ignore)
+ 		&& not (Hashtbl.mem acc hist_rec.con)
+ 		&& f hist_rec
+ 		then Hashtbl.replace acc hist_rec.con ();
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index 5e5a1ab..b56e3fc 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -350,7 +350,7 @@ let transaction_replay c t doms cons =
+ 					then (punish hist_rec.History.con; true)
+ 					else false
+ 				) in
+-				let guilty_cons = History.filter_connections ~since:t.Transaction.start_count ~f:judge_and_sentence in
++				let guilty_cons = History.filter_connections ~ignore:c ~since:t.Transaction.start_count ~f:judge_and_sentence in
+ 				if Hashtbl.length guilty_cons = 0 then debug "Found no culprit for conflict in %s: must be self or not in history." con;
+ 				false
+ 			)
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0013-oxenstored-do-not-commit-read-only-transactions.patch b/system/xen/xsa/xsa206-4.8-0013-oxenstored-do-not-commit-read-only-transactions.patch
new file mode 100644
index 000000000000..e6b066e40a34
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0013-oxenstored-do-not-commit-read-only-transactions.patch
@@ -0,0 +1,59 @@
+From f45ce51771c7e96c8ac8179c44476f8fc6168636 Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Fri, 24 Mar 2017 16:16:10 +0000
+Subject: [PATCH 13/15] oxenstored: do not commit read-only transactions
+
+The packet telling us to end the transaction has always carried an
+argument telling us whether to commit.
+
+If the transaction made no modifications to the tree, now we ignore
+that argument and do not commit: it is just a waste of effort.
+
+This makes read-only transactions immune to conflicts, and means that
+we do not need to store any of their details in the history that is
+used for assigning blame for conflicts.
+
+We count a transaction as a read-only transaction only if it contains
+no operations that modified the tree.
+
+This means that (for example) a transaction that creates a new node
+then deletes it would NOT count as read-only, even though it makes no
+change overall. A more sophisticated algorithm could judge the
+transaction based on comparison of its initial and final states, but
+this would add complexity and computational cost.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+---
+ tools/ocaml/xenstored/process.ml     | 1 +
+ tools/ocaml/xenstored/transaction.ml | 1 +
+ 2 files changed, 2 insertions(+)
+
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index b56e3fc..adfc7a4 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -393,6 +393,7 @@ let do_transaction_end con t domains cons data =
+ 		| x :: _   -> raise (Invalid_argument x)
+ 		| _        -> raise Invalid_Cmd_Args
+ 		in
++	let commit = commit && not (Transaction.is_read_only t) in
+ 	let success =
+ 		let commit = if commit then Some (fun con trans -> transaction_replay con trans domains cons) else None in
+ 		History.end_transaction t con (Transaction.get_id t) commit in
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index edd1178..8f95301 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -128,6 +128,7 @@ let make ?(internal=false) id store =
+ let get_store t = t.store
+ let get_paths t = t.paths
+ 
++let is_read_only t = t.paths = []
+ let add_wop t ty path = t.paths <- (ty, path) :: t.paths
+ let add_operation ~perm t request response =
+ 	if !Define.maxrequests >= 0
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0014-oxenstored-don-t-wake-to-issue-no-conflict-credit.patch b/system/xen/xsa/xsa206-4.8-0014-oxenstored-don-t-wake-to-issue-no-conflict-credit.patch
new file mode 100644
index 000000000000..8aae2814066d
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0014-oxenstored-don-t-wake-to-issue-no-conflict-credit.patch
@@ -0,0 +1,141 @@
+From 374c6a67e3d139a04ecde127a63ce70d24ed7b45 Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Fri, 24 Mar 2017 19:55:03 +0000
+Subject: [PATCH 14/15] oxenstored: don't wake to issue no conflict-credit
+
+In the main loop, when choosing the timeout for the select function
+call, we were setting it so as to wake up to issue conflict-credit to
+any domains that could accept it. When xenstore is idle, this would
+mean waking up every 50ms (by default) to do no work. With this
+commit, we check whether any domain is below its cap, and if not then
+we set the timeout for longer (the same timeout as before the
+conflict-protection feature was added).
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
+---
+ tools/ocaml/xenstored/domains.ml   | 51 ++++++++++++++++++++++++++++++--------
+ tools/ocaml/xenstored/xenstored.ml |  5 +++-
+ 2 files changed, 44 insertions(+), 12 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
+index 99f68c7..61d1e2e 100644
+--- a/tools/ocaml/xenstored/domains.ml
++++ b/tools/ocaml/xenstored/domains.ml
+@@ -35,8 +35,9 @@ type domains = {
+ 	on_first_conflict_pause: unit -> unit;
+ 
+ 	(* If config is set to use individual instead of aggregate conflict-rate-limiting,
+-	   we use this instead of the queues. *)
+-	mutable n_paused: int;
++	   we use these counts instead of the queues. The second one includes the first. *)
++	mutable n_paused: int;    (* Number of domains with zero or negative credit *)
++	mutable n_penalised: int; (* Number of domains with less than maximum credit *)
+ }
+ 
+ let init eventchn on_first_conflict_pause = {
+@@ -46,6 +47,7 @@ let init eventchn on_first_conflict_pause = {
+ 	doms_with_conflict_penalty = Queue.create ();
+ 	on_first_conflict_pause = on_first_conflict_pause;
+ 	n_paused = 0;
++	n_penalised = 0;
+ }
+ let del doms id = Hashtbl.remove doms.table id
+ let exist doms id = Hashtbl.mem doms.table id
+@@ -53,6 +55,23 @@ let find doms id = Hashtbl.find doms.table id
+ let number doms = Hashtbl.length doms.table
+ let iter doms fct = Hashtbl.iter (fun _ b -> fct b) doms.table
+ 
++let rec is_empty_queue q =
++	Queue.is_empty q ||
++		if !(Queue.peek q) = None
++		then (
++			ignore (Queue.pop q);
++			is_empty_queue q
++		) else false
++
++let all_at_max_credit doms =
++	if !Define.conflict_rate_limit_is_aggregate
++	then
++		(* Check both becuase if burst limit is 1.0 then a domain can go straight
++		 * from max-credit to paused without getting into the penalty queue. *)
++		is_empty_queue doms.doms_with_conflict_penalty
++		&& is_empty_queue doms.doms_conflict_paused
++	else doms.n_penalised = 0
++
+ (* Functions to handle queues of domains given that the domain might be deleted while in a queue. *)
+ let push dom queue =
+ 	Queue.push (ref (Some dom)) queue
+@@ -130,13 +149,16 @@ let decr_conflict_credit doms dom =
+ 	let before = dom.Domain.conflict_credit in
+ 	let after = max (-1.0) (before -. 1.0) in
+ 	dom.Domain.conflict_credit <- after;
++	let newly_penalised =
++		before >= !Define.conflict_burst_limit
++		&& after < !Define.conflict_burst_limit in
++	let newly_paused = before > 0.0 && after <= 0.0 in
+ 	if !Define.conflict_rate_limit_is_aggregate then (
+-		if before >= !Define.conflict_burst_limit
+-		&& after < !Define.conflict_burst_limit
++		if newly_penalised
+ 		&& after > 0.0
+ 		then (
+ 			push dom doms.doms_with_conflict_penalty
+-		) else if before > 0.0 && after <= 0.0
++		) else if newly_paused
+ 		then (
+ 			let first_pause = Queue.is_empty doms.doms_conflict_paused in
+ 			push dom doms.doms_conflict_paused;
+@@ -144,9 +166,12 @@ let decr_conflict_credit doms dom =
+ 		) else (
+ 			(* The queues are correct already: no further action needed. *)
+ 		)
+-	) else if before > 0.0 && after <= 0.0 then (
+-		doms.n_paused <- doms.n_paused + 1;
+-		if doms.n_paused = 1 then doms.on_first_conflict_pause ()
++	) else (
++		if newly_penalised then doms.n_penalised <- doms.n_penalised + 1;
++		if newly_paused then (
++			doms.n_paused <- doms.n_paused + 1;
++			if doms.n_paused = 1 then doms.on_first_conflict_pause ()
++		)
+ 	)
+ 
+ (* Give one point of credit to one domain, and update the queues appropriately. *)
+@@ -175,9 +200,13 @@ let incr_conflict_credit doms =
+ 			let before = dom.Domain.conflict_credit in
+ 			let after = min (before +. 1.0) !Define.conflict_burst_limit in
+ 			dom.Domain.conflict_credit <- after;
++
+ 			if before <= 0.0 && after > 0.0
+-			then doms.n_paused <- doms.n_paused - 1
++			then doms.n_paused <- doms.n_paused - 1;
++
++			if before < !Define.conflict_burst_limit
++			&& after >= !Define.conflict_burst_limit
++			then doms.n_penalised <- doms.n_penalised - 1
+ 		in
+-		(* Scope for optimisation (probably tiny): avoid iteration if all domains are at max credit *)
+-		iter doms inc
++		if doms.n_penalised > 0 then iter doms inc
+ 	)
+diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
+index d5c50fd..06387a8 100644
+--- a/tools/ocaml/xenstored/xenstored.ml
++++ b/tools/ocaml/xenstored/xenstored.ml
+@@ -437,7 +437,10 @@ let _ =
+ 			peaceful_mw;
+ 		let start_time = Unix.gettimeofday () in
+ 		let timeout =
+-			let until_next_activity = min (max 0. (!next_frequent_ops -. start_time)) period_ops_interval in
++			let until_next_activity =
++				if Domains.all_at_max_credit domains
++				then period_ops_interval
++				else min (max 0. (!next_frequent_ops -. start_time)) period_ops_interval in
+ 			if peaceful_mw <> [] then 0. else until_next_activity
+ 		in
+ 		let inset, outset = Connections.select ~only_if:is_peaceful cons in
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0015-oxenstored-transaction-conflicts-improve-logging.patch b/system/xen/xsa/xsa206-4.8-0015-oxenstored-transaction-conflicts-improve-logging.patch
new file mode 100644
index 000000000000..bc46ed1ac5ee
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0015-oxenstored-transaction-conflicts-improve-logging.patch
@@ -0,0 +1,153 @@
+From d7d0c021115d40177035a0626ed47681b034b584 Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Mon, 27 Mar 2017 14:36:34 +0100
+Subject: [PATCH 15/15] oxenstored transaction conflicts: improve logging
+
+For information related to transaction conflicts, potentially frequent
+logging at "info" priority has been changed to "debug" priority, and
+once per two minutes there is an "info" priority summary.
+
+Additional detailed logging has been added at "debug" priority.
+
+Reported-by: Juergen Gross <jgross@suse.com>
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+---
+ tools/ocaml/xenstored/domain.ml      | 8 ++++++++
+ tools/ocaml/xenstored/domains.ml     | 5 +++++
+ tools/ocaml/xenstored/process.ml     | 6 +++++-
+ tools/ocaml/xenstored/transaction.ml | 5 +++++
+ tools/ocaml/xenstored/xenstored.ml   | 6 ++++++
+ 5 files changed, 29 insertions(+), 1 deletion(-)
+
+diff --git a/tools/ocaml/xenstored/domain.ml b/tools/ocaml/xenstored/domain.ml
+index e677aa3..4515650 100644
+--- a/tools/ocaml/xenstored/domain.ml
++++ b/tools/ocaml/xenstored/domain.ml
+@@ -34,6 +34,7 @@ type t =
+ 	mutable conflict_credit: float; (* Must be positive to perform writes; a commit
+ 	                                   that later causes conflict with another
+ 	                                   domain's transaction costs credit. *)
++	mutable caused_conflicts: int64;
+ }
+ 
+ let is_dom0 d = d.id = 0
+@@ -93,4 +94,11 @@ let make id mfn remote_port interface eventchn = {
+ 	bad_client = false;
+ 	io_credit = 0;
+ 	conflict_credit = !Define.conflict_burst_limit;
++	caused_conflicts = 0L;
+ }
++
++let log_and_reset_conflict_stats logfn dom =
++	if dom.caused_conflicts > 0L then (
++		logfn dom.id dom.caused_conflicts;
++		dom.caused_conflicts <- 0L
++	)
+diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
+index 61d1e2e..fdae298 100644
+--- a/tools/ocaml/xenstored/domains.ml
++++ b/tools/ocaml/xenstored/domains.ml
+@@ -146,8 +146,10 @@ let create0 doms =
+ 	dom
+ 
+ let decr_conflict_credit doms dom =
++	dom.Domain.caused_conflicts <- Int64.add 1L dom.Domain.caused_conflicts;
+ 	let before = dom.Domain.conflict_credit in
+ 	let after = max (-1.0) (before -. 1.0) in
++	debug "decr_conflict_credit dom%d %F -> %F" (Domain.get_id dom) before after;
+ 	dom.Domain.conflict_credit <- after;
+ 	let newly_penalised =
+ 		before >= !Define.conflict_burst_limit
+@@ -178,7 +180,9 @@ let decr_conflict_credit doms dom =
+ let incr_conflict_credit_from_queue doms =
+ 	let process_queue q requeue_test =
+ 		let d = pop q in
++		let before = d.Domain.conflict_credit in (* just for debug-logging *)
+ 		d.Domain.conflict_credit <- min (d.Domain.conflict_credit +. 1.0) !Define.conflict_burst_limit;
++		debug "incr_conflict_credit_from_queue: dom%d: %F -> %F" (Domain.get_id d) before d.Domain.conflict_credit;
+ 		if requeue_test d.Domain.conflict_credit then (
+ 			push d q (* Make it queue up again for its next point of credit. *)
+ 		)
+@@ -200,6 +204,7 @@ let incr_conflict_credit doms =
+ 			let before = dom.Domain.conflict_credit in
+ 			let after = min (before +. 1.0) !Define.conflict_burst_limit in
+ 			dom.Domain.conflict_credit <- after;
++			debug "incr_conflict_credit dom%d: %F -> %F" (Domain.get_id dom) before after;
+ 
+ 			if before <= 0.0 && after > 0.0
+ 			then doms.n_paused <- doms.n_paused - 1;
+diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
+index adfc7a4..8a688c4 100644
+--- a/tools/ocaml/xenstored/process.ml
++++ b/tools/ocaml/xenstored/process.ml
+@@ -330,6 +330,7 @@ let transaction_replay c t doms cons =
+ 				Transaction.commit ~con replay_t
+ 			with
+ 			| Transaction_again -> (
++				Transaction.failed_commits := Int64.add !Transaction.failed_commits 1L;
+ 				let victim_domstr = Connection.get_domstr c in
+ 				debug "Apportioning blame for EAGAIN in txn %d, domain=%s" id victim_domstr;
+ 				let punish guilty_con =
+@@ -351,7 +352,10 @@ let transaction_replay c t doms cons =
+ 					else false
+ 				) in
+ 				let guilty_cons = History.filter_connections ~ignore:c ~since:t.Transaction.start_count ~f:judge_and_sentence in
+-				if Hashtbl.length guilty_cons = 0 then debug "Found no culprit for conflict in %s: must be self or not in history." con;
++				if Hashtbl.length guilty_cons = 0 then (
++					debug "Found no culprit for conflict in %s: must be self or not in history." con;
++					Transaction.failed_commits_no_culprit := Int64.add !Transaction.failed_commits_no_culprit 1L
++				);
+ 				false
+ 			)
+ 			| e ->
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index 8f95301..da4a3e3 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -90,6 +90,11 @@ type t = {
+ let get_id t = match t.ty with No -> none | Full (id, _, _) -> id
+ 
+ let counter = ref 0L
++let failed_commits = ref 0L
++let failed_commits_no_culprit = ref 0L
++let reset_conflict_stats () =
++	failed_commits := 0L;
++	failed_commits_no_culprit := 0L
+ 
+ (* Scope for optimisation: different data-structure and functions to search/filter it *)
+ let short_running_txns = ref []
+diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
+index 06387a8..05ace4d 100644
+--- a/tools/ocaml/xenstored/xenstored.ml
++++ b/tools/ocaml/xenstored/xenstored.ml
+@@ -376,6 +376,7 @@ let _ =
+ 	let last_scan_time = ref 0. in
+ 
+ 	let periodic_ops now =
++		debug "periodic_ops starting";
+ 		(* we garbage collect the string->int dictionary after a sizeable amount of operations,
+ 		 * there's no need to be really fast even if we got loose
+ 		 * objects since names are often reuse.
+@@ -395,7 +396,11 @@ let _ =
+ 
+ 		(* make sure we don't print general stats faster than 2 min *)
+ 		if now > (!last_stat_time +. 120.) then (
++			info "Transaction conflict statistics for last %F seconds:" (now -. !last_stat_time);
+ 			last_stat_time := now;
++			Domains.iter domains (Domain.log_and_reset_conflict_stats (info "Dom%d caused %Ld conflicts"));
++			info "%Ld failed transactions; of these no culprit was found for %Ld" !Transaction.failed_commits !Transaction.failed_commits_no_culprit;
++			Transaction.reset_conflict_stats ();
+ 
+ 			let gc = Gc.stat () in
+ 			let (lanon, lanon_ops, lanon_watchs,
+@@ -415,6 +420,7 @@ let _ =
+ 			     gc.Gc.free_words gc.Gc.free_blocks
+ 		);
+ 		let elapsed = Unix.gettimeofday () -. now in
++		debug "periodic_ops took %F seconds." elapsed;
+ 		delay_next_frequent_ops_by elapsed
+ 	in
+ 
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa206-4.8-0016-oxenstored-trim-history-in-the-frequent_ops-function.patch b/system/xen/xsa/xsa206-4.8-0016-oxenstored-trim-history-in-the-frequent_ops-function.patch
new file mode 100644
index 000000000000..40102efceb70
--- /dev/null
+++ b/system/xen/xsa/xsa206-4.8-0016-oxenstored-trim-history-in-the-frequent_ops-function.patch
@@ -0,0 +1,79 @@
+From 26b15d4eb7ac71fcab28a7fca664afa0549c135c Mon Sep 17 00:00:00 2001
+From: Thomas Sanders <thomas.sanders@citrix.com>
+Date: Tue, 28 Mar 2017 18:57:52 +0100
+Subject: [PATCH 16/15] oxenstored: trim history in the frequent_ops function
+
+We were trimming the history of commits only at the end of each
+transaction (regardless of how it ended).
+
+Therefore if non-transactional writes were being made but no
+transactions were being ended, the history would grow
+indefinitely. Now we trim the history at regular intervals.
+
+Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
+---
+ tools/ocaml/xenstored/history.ml     |    6 +++---
+ tools/ocaml/xenstored/transaction.ml |    8 ++++++--
+ tools/ocaml/xenstored/xenstored.ml   |    1 +
+ 3 files changed, 10 insertions(+), 5 deletions(-)
+
+diff --git a/tools/ocaml/xenstored/history.ml b/tools/ocaml/xenstored/history.ml
+index 4079588..f39565b 100644
+--- a/tools/ocaml/xenstored/history.ml
++++ b/tools/ocaml/xenstored/history.ml
+@@ -39,7 +39,8 @@ let mark_symbols () =
+ (* Keep only enough commit-history to protect the running transactions that we are still tracking *)
+ (* There is scope for optimisation here, replacing List.filter with something more efficient,
+  * probably on a different list-like structure. *)
+-let trim () =
++let trim ?txn () =
++	Transaction.trim_short_running_transactions txn;
+ 	history := match Transaction.oldest_short_running_transaction () with
+ 	| None -> [] (* We have no open transaction, so no history is needed *)
+ 	| Some (_, txn) -> (
+@@ -49,8 +50,7 @@ let trim () =
+ 
+ let end_transaction txn con tid commit =
+ 	let success = Connection.end_transaction con tid commit in
+-	Transaction.end_transaction txn;
+-	trim ();
++	trim ~txn ();
+ 	success
+ 
+ let push (x: history_record) =
+diff --git a/tools/ocaml/xenstored/transaction.ml b/tools/ocaml/xenstored/transaction.ml
+index da4a3e3..23e7ccf 100644
+--- a/tools/ocaml/xenstored/transaction.ml
++++ b/tools/ocaml/xenstored/transaction.ml
+@@ -106,10 +106,14 @@ let oldest_short_running_transaction () =
+ 		| x :: xs -> last xs
+ 	in last !short_running_txns
+ 
+-let end_transaction txn =
++let trim_short_running_transactions txn =
+ 	let cutoff = Unix.gettimeofday () -. !Define.conflict_max_history_seconds in
++	let keep = match txn with
++		| None -> (function (start_time, _) -> start_time >= cutoff)
++		| Some t -> (function (start_time, tx) -> start_time >= cutoff && tx != t)
++	in
+ 	short_running_txns := List.filter
+-		(function (start_time, tx) -> start_time >= cutoff && tx != txn)
++		keep
+ 		!short_running_txns
+ 
+ let make ?(internal=false) id store =
+diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
+index 92ea99e..c45146d 100644
+--- a/tools/ocaml/xenstored/xenstored.ml
++++ b/tools/ocaml/xenstored/xenstored.ml
+@@ -280,6 +280,7 @@ let _ =
+ 	 * than the periodic_ops function *)
+ 	let frequent_ops () =
+ 		if Unix.gettimeofday () > !next_frequent_ops then (
++			History.trim ();
+ 			Domains.incr_conflict_credit domains;
+ 			advance_next_frequent_ops ()
+ 		) in
+-- 
+1.7.9.5
+
diff --git a/system/xen/xsa/xsa211-qemut.patch b/system/xen/xsa/xsa211-qemut.patch
new file mode 100644
index 000000000000..59e12fb31e25
--- /dev/null
+++ b/system/xen/xsa/xsa211-qemut.patch
@@ -0,0 +1,225 @@
+From 29e67cfd46b4d06ca1bb75558e227ec34a6af35f Mon Sep 17 00:00:00 2001
+From: Ian Jackson <ian.jackson@eu.citrix.com>
+Date: Thu, 9 Mar 2017 11:14:55 +0000
+Subject: [PATCH] cirrus/vnc: zap drop bitblit support from console code.
+
+From: Gerd Hoffmann <kraxel@redhat.com>
+
+There is a special code path (dpy_gfx_copy) to allow graphic emulation
+notify user interface code about bitblit operations carryed out by
+guests.  It is supported by cirrus and vnc server.  The intended purpose
+is to optimize display scrolls and just send over the scroll op instead
+of a full display update.
+
+This is rarely used these days though because modern guests simply don't
+use the cirrus blitter any more.  Any linux guest using the cirrus drm
+driver doesn't.  Any windows guest newer than winxp doesn't ship with a
+cirrus driver any more and thus uses the cirrus as simple framebuffer.
+
+So this code tends to bitrot and bugs can go unnoticed for a long time.
+See for example commit "3e10c3e vnc: fix qemu crash because of SIGSEGV"
+which fixes a bug lingering in the code for almost a year, added by
+commit "c7628bf vnc: only alloc server surface with clients connected".
+
+Also the vnc server will throttle the frame rate in case it figures the
+network can't keep up (send buffers are full).  This doesn't work with
+dpy_gfx_copy, for any copy operation sent to the vnc client we have to
+send all outstanding updates beforehand, otherwise the vnc client might
+run the client side blit on outdated data and thereby corrupt the
+display.  So this dpy_gfx_copy "optimization" might even make things
+worse on slow network links.
+
+Lets kill it once for all.
+
+Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
+
+These changes (dropping dpy_copy and all its references and
+implementations) reimplemented for qemu-xen-traditional.
+
+This is XSA-211.
+
+Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
+---
+ console.c       |  8 --------
+ console.h       | 16 ----------------
+ hw/cirrus_vga.c | 15 +++++----------
+ hw/vmware_vga.c |  1 +
+ vnc.c           | 35 -----------------------------------
+ 5 files changed, 6 insertions(+), 69 deletions(-)
+
+diff --git a/console.c b/console.c
+index d4f1ad0..e61b53b 100644
+--- a/console.c
++++ b/console.c
+@@ -1399,14 +1399,6 @@ void qemu_console_resize(DisplayState *ds, int width, int height)
+     }
+ }
+ 
+-void qemu_console_copy(DisplayState *ds, int src_x, int src_y,
+-                int dst_x, int dst_y, int w, int h)
+-{
+-    if (is_graphic_console()) {
+-        dpy_copy(ds, src_x, src_y, dst_x, dst_y, w, h);
+-    }
+-}
+-
+ PixelFormat qemu_different_endianness_pixelformat(int bpp)
+ {
+     PixelFormat pf;
+diff --git a/console.h b/console.h
+index 14b42f3..8306cc4 100644
+--- a/console.h
++++ b/console.h
+@@ -98,8 +98,6 @@ struct DisplayChangeListener {
+     void (*dpy_resize)(struct DisplayState *s);
+     void (*dpy_setdata)(struct DisplayState *s);
+     void (*dpy_refresh)(struct DisplayState *s);
+-    void (*dpy_copy)(struct DisplayState *s, int src_x, int src_y,
+-                     int dst_x, int dst_y, int w, int h);
+     void (*dpy_fill)(struct DisplayState *s, int x, int y,
+                      int w, int h, uint32_t c);
+     void (*dpy_text_cursor)(struct DisplayState *s, int x, int y);
+@@ -211,18 +209,6 @@ static inline void dpy_refresh(DisplayState *s)
+     }
+ }
+ 
+-static inline void dpy_copy(struct DisplayState *s, int src_x, int src_y,
+-                             int dst_x, int dst_y, int w, int h) {
+-    struct DisplayChangeListener *dcl = s->listeners;
+-    while (dcl != NULL) {
+-        if (dcl->dpy_copy)
+-            dcl->dpy_copy(s, src_x, src_y, dst_x, dst_y, w, h);
+-        else /* TODO */
+-            dcl->dpy_update(s, dst_x, dst_y, w, h);
+-        dcl = dcl->next;
+-    }
+-}
+-
+ static inline void dpy_fill(struct DisplayState *s, int x, int y,
+                              int w, int h, uint32_t c) {
+     struct DisplayChangeListener *dcl = s->listeners;
+@@ -297,8 +283,6 @@ void text_consoles_set_display(DisplayState *ds);
+ void console_select(unsigned int index);
+ void console_color_init(DisplayState *ds);
+ void qemu_console_resize(DisplayState *ds, int width, int height);
+-void qemu_console_copy(DisplayState *ds, int src_x, int src_y,
+-                int dst_x, int dst_y, int w, int h);
+ 
+ /* sdl.c */
+ void sdl_display_init(DisplayState *ds, int full_screen, int no_frame, int opengl_enabled);
+diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
+index 06b4a3b..4e85b90 100644
+--- a/hw/cirrus_vga.c
++++ b/hw/cirrus_vga.c
+@@ -793,11 +793,6 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
+         }
+     }
+ 
+-    /* we have to flush all pending changes so that the copy
+-       is generated at the appropriate moment in time */
+-    if (notify)
+-	vga_hw_update();
+-
+     (*s->cirrus_rop) (s, s->vram_ptr +
+ 		      (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
+ 		      s->vram_ptr +
+@@ -806,13 +801,13 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
+ 		      s->cirrus_blt_width, s->cirrus_blt_height);
+ 
+     if (notify)
+-	qemu_console_copy(s->ds,
+-			  sx, sy, dx, dy,
+-			  s->cirrus_blt_width / depth,
+-			  s->cirrus_blt_height);
++	dpy_update(s->ds,
++                   dx, dy,
++                   s->cirrus_blt_width / depth,
++                   s->cirrus_blt_height);
+ 
+     /* we don't have to notify the display that this portion has
+-       changed since qemu_console_copy implies this */
++       changed since dpy_update implies this */
+ 
+     cirrus_invalidate_region(s, s->cirrus_blt_dstaddr,
+ 				s->cirrus_blt_dstpitch, s->cirrus_blt_width,
+diff --git a/hw/vmware_vga.c b/hw/vmware_vga.c
+index d1cba28..c38e43c 100644
+--- a/hw/vmware_vga.c
++++ b/hw/vmware_vga.c
+@@ -383,6 +383,7 @@ static inline void vmsvga_copy_rect(struct vmsvga_state_s *s,
+ 
+ # ifdef DIRECT_VRAM
+     if (s->ds->dpy_copy)
++#  error This configuration is not supported.  See XSA-211.
+         qemu_console_copy(s->ds, x0, y0, x1, y1, w, h);
+     else
+ # endif
+diff --git a/vnc.c b/vnc.c
+index 61d1555..0e61197 100644
+--- a/vnc.c
++++ b/vnc.c
+@@ -572,36 +572,6 @@ static void send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
+ 	    send_framebuffer_update_raw(vs, x, y, w, h);
+ }
+ 
+-static void vnc_copy(DisplayState *ds, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
+-{
+-    VncState *vs = ds->opaque;
+-    int updating_client = 1;
+-
+-    if (!vs->update_requested ||
+-        src_x < vs->visible_x || src_y < vs->visible_y ||
+-	dst_x < vs->visible_x || dst_y < vs->visible_y ||
+-	(src_x + w) > (vs->visible_x + vs->visible_w) ||
+-	(src_y + h) > (vs->visible_y + vs->visible_h) ||
+-	(dst_x + w) > (vs->visible_x + vs->visible_w) ||
+-	(dst_y + h) > (vs->visible_y + vs->visible_h))
+-	updating_client = 0;
+-
+-    if (updating_client)
+-        _vnc_update_client(vs);
+-
+-    if (updating_client && vs->csock != -1 && !vs->has_update) {
+-	vnc_write_u8(vs, 0);  /* msg id */
+-	vnc_write_u8(vs, 0);
+-	vnc_write_u16(vs, 1); /* number of rects */
+-	vnc_framebuffer_update(vs, dst_x, dst_y, w, h, 1);
+-	vnc_write_u16(vs, src_x);
+-	vnc_write_u16(vs, src_y);
+-	vnc_flush(vs);
+-        vs->update_requested--;
+-    } else
+-	framebuffer_set_updated(vs, dst_x, dst_y, w, h);
+-}
+-
+ static int find_update_height(VncState *vs, int y, int maxy, int last_x, int x)
+ {
+     int h;
+@@ -1543,16 +1513,12 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
+     vs->has_pointer_type_change = 0;
+     vs->has_WMVi = 0;
+     vs->absolute = -1;
+-    dcl->dpy_copy = NULL;
+ 
+     for (i = n_encodings - 1; i >= 0; i--) {
+ 	switch (encodings[i]) {
+ 	case 0: /* Raw */
+ 	    vs->has_hextile = 0;
+ 	    break;
+-	case 1: /* CopyRect */
+-	    dcl->dpy_copy = vnc_copy;
+-	    break;
+ 	case 5: /* Hextile */
+ 	    vs->has_hextile = 1;
+ 	    break;
+@@ -2459,7 +2425,6 @@ static void vnc_listen_read(void *opaque)
+ 	vs->has_resize = 0;
+ 	vs->has_hextile = 0;
+         vs->update_requested = 0;
+-	dcl->dpy_copy = NULL;
+ 	vnc_timer_init(vs);
+     }
+ }
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa211-qemuu-4.8.patch b/system/xen/xsa/xsa211-qemuu-4.8.patch
new file mode 100644
index 000000000000..aabdd11ae372
--- /dev/null
+++ b/system/xen/xsa/xsa211-qemuu-4.8.patch
@@ -0,0 +1,264 @@
+From 7563ddb0bd67e7e54568e017cb7d4f7f556587fc Mon Sep 17 00:00:00 2001
+From: Gerd Hoffmann <kraxel@redhat.com>
+Date: Tue, 14 Feb 2017 19:09:59 +0100
+Subject: [PATCH] cirrus/vnc: zap bitblit support from console code.
+
+There is a special code path (dpy_gfx_copy) to allow graphic emulation
+notify user interface code about bitblit operations carryed out by
+guests.  It is supported by cirrus and vnc server.  The intended purpose
+is to optimize display scrolls and just send over the scroll op instead
+of a full display update.
+
+This is rarely used these days though because modern guests simply don't
+use the cirrus blitter any more.  Any linux guest using the cirrus drm
+driver doesn't.  Any windows guest newer than winxp doesn't ship with a
+cirrus driver any more and thus uses the cirrus as simple framebuffer.
+
+So this code tends to bitrot and bugs can go unnoticed for a long time.
+See for example commit "3e10c3e vnc: fix qemu crash because of SIGSEGV"
+which fixes a bug lingering in the code for almost a year, added by
+commit "c7628bf vnc: only alloc server surface with clients connected".
+
+Also the vnc server will throttle the frame rate in case it figures the
+network can't keep up (send buffers are full).  This doesn't work with
+dpy_gfx_copy, for any copy operation sent to the vnc client we have to
+send all outstanding updates beforehand, otherwise the vnc client might
+run the client side blit on outdated data and thereby corrupt the
+display.  So this dpy_gfx_copy "optimization" might even make things
+worse on slow network links.
+
+Lets kill it once for all.
+
+Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
+---
+ hw/display/cirrus_vga.c | 12 ++-----
+ include/ui/console.h    |  7 ----
+ ui/console.c            | 28 ---------------
+ ui/vnc.c                | 96 -------------------------------------------------
+ 4 files changed, 3 insertions(+), 140 deletions(-)
+
+diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
+index 9a4e90a..2966125 100644
+--- a/hw/display/cirrus_vga.c
++++ b/hw/display/cirrus_vga.c
+@@ -760,11 +760,6 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
+         }
+     }
+ 
+-    /* we have to flush all pending changes so that the copy
+-       is generated at the appropriate moment in time */
+-    if (notify)
+-        graphic_hw_update(s->vga.con);
+-
+     (*s->cirrus_rop) (s, s->vga.vram_ptr +
+ 		      (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
+ 		      s->vga.vram_ptr +
+@@ -773,10 +768,9 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
+ 		      s->cirrus_blt_width, s->cirrus_blt_height);
+ 
+     if (notify) {
+-        qemu_console_copy(s->vga.con,
+-			  sx, sy, dx, dy,
+-			  s->cirrus_blt_width / depth,
+-			  s->cirrus_blt_height);
++        dpy_gfx_update(s->vga.con, dx, dy,
++                       s->cirrus_blt_width / depth,
++                       s->cirrus_blt_height);
+     }
+ 
+     /* we don't have to notify the display that this portion has
+diff --git a/include/ui/console.h b/include/ui/console.h
+index 2703a3a..67927ed 100644
+--- a/include/ui/console.h
++++ b/include/ui/console.h
+@@ -189,9 +189,6 @@ typedef struct DisplayChangeListenerOps {
+                            int x, int y, int w, int h);
+     void (*dpy_gfx_switch)(DisplayChangeListener *dcl,
+                            struct DisplaySurface *new_surface);
+-    void (*dpy_gfx_copy)(DisplayChangeListener *dcl,
+-                         int src_x, int src_y,
+-                         int dst_x, int dst_y, int w, int h);
+     bool (*dpy_gfx_check_format)(DisplayChangeListener *dcl,
+                                  pixman_format_code_t format);
+ 
+@@ -273,8 +270,6 @@ int dpy_set_ui_info(QemuConsole *con, QemuUIInfo *info);
+ void dpy_gfx_update(QemuConsole *con, int x, int y, int w, int h);
+ void dpy_gfx_replace_surface(QemuConsole *con,
+                              DisplaySurface *surface);
+-void dpy_gfx_copy(QemuConsole *con, int src_x, int src_y,
+-                  int dst_x, int dst_y, int w, int h);
+ void dpy_text_cursor(QemuConsole *con, int x, int y);
+ void dpy_text_update(QemuConsole *con, int x, int y, int w, int h);
+ void dpy_text_resize(QemuConsole *con, int w, int h);
+@@ -398,8 +393,6 @@ void text_consoles_set_display(DisplayState *ds);
+ void console_select(unsigned int index);
+ void console_color_init(DisplayState *ds);
+ void qemu_console_resize(QemuConsole *con, int width, int height);
+-void qemu_console_copy(QemuConsole *con, int src_x, int src_y,
+-                       int dst_x, int dst_y, int w, int h);
+ DisplaySurface *qemu_console_surface(QemuConsole *con);
+ 
+ /* console-gl.c */
+diff --git a/ui/console.c b/ui/console.c
+index c24bfe4..ece0c04 100644
+--- a/ui/console.c
++++ b/ui/console.c
+@@ -1558,27 +1558,6 @@ static void dpy_refresh(DisplayState *s)
+     }
+ }
+ 
+-void dpy_gfx_copy(QemuConsole *con, int src_x, int src_y,
+-                  int dst_x, int dst_y, int w, int h)
+-{
+-    DisplayState *s = con->ds;
+-    DisplayChangeListener *dcl;
+-
+-    if (!qemu_console_is_visible(con)) {
+-        return;
+-    }
+-    QLIST_FOREACH(dcl, &s->listeners, next) {
+-        if (con != (dcl->con ? dcl->con : active_console)) {
+-            continue;
+-        }
+-        if (dcl->ops->dpy_gfx_copy) {
+-            dcl->ops->dpy_gfx_copy(dcl, src_x, src_y, dst_x, dst_y, w, h);
+-        } else { /* TODO */
+-            dcl->ops->dpy_gfx_update(dcl, dst_x, dst_y, w, h);
+-        }
+-    }
+-}
+-
+ void dpy_text_cursor(QemuConsole *con, int x, int y)
+ {
+     DisplayState *s = con->ds;
+@@ -2104,13 +2083,6 @@ void qemu_console_resize(QemuConsole *s, int width, int height)
+     dpy_gfx_replace_surface(s, surface);
+ }
+ 
+-void qemu_console_copy(QemuConsole *con, int src_x, int src_y,
+-                       int dst_x, int dst_y, int w, int h)
+-{
+-    assert(con->console_type == GRAPHIC_CONSOLE);
+-    dpy_gfx_copy(con, src_x, src_y, dst_x, dst_y, w, h);
+-}
+-
+ DisplaySurface *qemu_console_surface(QemuConsole *console)
+ {
+     return console->surface;
+diff --git a/ui/vnc.c b/ui/vnc.c
+index d1087c9..b45bb2c 100644
+--- a/ui/vnc.c
++++ b/ui/vnc.c
+@@ -872,101 +872,6 @@ int vnc_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
+     return n;
+ }
+ 
+-static void vnc_copy(VncState *vs, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
+-{
+-    /* send bitblit op to the vnc client */
+-    vnc_lock_output(vs);
+-    vnc_write_u8(vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
+-    vnc_write_u8(vs, 0);
+-    vnc_write_u16(vs, 1); /* number of rects */
+-    vnc_framebuffer_update(vs, dst_x, dst_y, w, h, VNC_ENCODING_COPYRECT);
+-    vnc_write_u16(vs, src_x);
+-    vnc_write_u16(vs, src_y);
+-    vnc_unlock_output(vs);
+-    vnc_flush(vs);
+-}
+-
+-static void vnc_dpy_copy(DisplayChangeListener *dcl,
+-                         int src_x, int src_y,
+-                         int dst_x, int dst_y, int w, int h)
+-{
+-    VncDisplay *vd = container_of(dcl, VncDisplay, dcl);
+-    VncState *vs, *vn;
+-    uint8_t *src_row;
+-    uint8_t *dst_row;
+-    int i, x, y, pitch, inc, w_lim, s;
+-    int cmp_bytes;
+-
+-    if (!vd->server) {
+-        /* no client connected */
+-        return;
+-    }
+-
+-    vnc_refresh_server_surface(vd);
+-    QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
+-        if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
+-            vs->force_update = 1;
+-            vnc_update_client(vs, 1, true);
+-            /* vs might be free()ed here */
+-        }
+-    }
+-
+-    /* do bitblit op on the local surface too */
+-    pitch = vnc_server_fb_stride(vd);
+-    src_row = vnc_server_fb_ptr(vd, src_x, src_y);
+-    dst_row = vnc_server_fb_ptr(vd, dst_x, dst_y);
+-    y = dst_y;
+-    inc = 1;
+-    if (dst_y > src_y) {
+-        /* copy backwards */
+-        src_row += pitch * (h-1);
+-        dst_row += pitch * (h-1);
+-        pitch = -pitch;
+-        y = dst_y + h - 1;
+-        inc = -1;
+-    }
+-    w_lim = w - (VNC_DIRTY_PIXELS_PER_BIT - (dst_x % VNC_DIRTY_PIXELS_PER_BIT));
+-    if (w_lim < 0) {
+-        w_lim = w;
+-    } else {
+-        w_lim = w - (w_lim % VNC_DIRTY_PIXELS_PER_BIT);
+-    }
+-    for (i = 0; i < h; i++) {
+-        for (x = 0; x <= w_lim;
+-                x += s, src_row += cmp_bytes, dst_row += cmp_bytes) {
+-            if (x == w_lim) {
+-                if ((s = w - w_lim) == 0)
+-                    break;
+-            } else if (!x) {
+-                s = (VNC_DIRTY_PIXELS_PER_BIT -
+-                    (dst_x % VNC_DIRTY_PIXELS_PER_BIT));
+-                s = MIN(s, w_lim);
+-            } else {
+-                s = VNC_DIRTY_PIXELS_PER_BIT;
+-            }
+-            cmp_bytes = s * VNC_SERVER_FB_BYTES;
+-            if (memcmp(src_row, dst_row, cmp_bytes) == 0)
+-                continue;
+-            memmove(dst_row, src_row, cmp_bytes);
+-            QTAILQ_FOREACH(vs, &vd->clients, next) {
+-                if (!vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
+-                    set_bit(((x + dst_x) / VNC_DIRTY_PIXELS_PER_BIT),
+-                            vs->dirty[y]);
+-                }
+-            }
+-        }
+-        src_row += pitch - w * VNC_SERVER_FB_BYTES;
+-        dst_row += pitch - w * VNC_SERVER_FB_BYTES;
+-        y += inc;
+-    }
+-
+-    QTAILQ_FOREACH(vs, &vd->clients, next) {
+-        if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
+-            vnc_copy(vs, src_x, src_y, dst_x, dst_y, w, h);
+-        }
+-    }
+-}
+-
+ static void vnc_mouse_set(DisplayChangeListener *dcl,
+                           int x, int y, int visible)
+ {
+@@ -3119,7 +3024,6 @@ static gboolean vnc_listen_io(QIOChannel *ioc,
+ static const DisplayChangeListenerOps dcl_ops = {
+     .dpy_name             = "vnc",
+     .dpy_refresh          = vnc_refresh,
+-    .dpy_gfx_copy         = vnc_dpy_copy,
+     .dpy_gfx_update       = vnc_dpy_update,
+     .dpy_gfx_switch       = vnc_dpy_switch,
+     .dpy_gfx_check_format = qemu_pixman_check_format,
+-- 
+2.1.4
+
diff --git a/system/xen/xsa/xsa212.patch b/system/xen/xsa/xsa212.patch
new file mode 100644
index 000000000000..2c435c413644
--- /dev/null
+++ b/system/xen/xsa/xsa212.patch
@@ -0,0 +1,87 @@
+memory: properly check guest memory ranges in XENMEM_exchange handling
+
+The use of guest_handle_okay() here (as introduced by the XSA-29 fix)
+is insufficient here, guest_handle_subrange_okay() needs to be used
+instead.
+
+Note that the uses are okay in
+- XENMEM_add_to_physmap_batch handling due to the size field being only
+  16 bits wide,
+- livepatch_list() due to the limit of 1024 enforced on the
+  number-of-entries input (leaving aside the fact that this can be
+  called by a privileged domain only anyway),
+- compat mode handling due to counts there being limited to 32 bits,
+- everywhere else due to guest arrays being accessed sequentially from
+  index zero.
+
+This is XSA-212.
+
+Reported-by: Jann Horn <jannh@google.com>
+Signed-off-by: Jan Beulich <jbeulich@suse.com>
+Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
+
+--- a/xen/common/memory.c
++++ b/xen/common/memory.c
+@@ -436,8 +436,8 @@ static long memory_exchange(XEN_GUEST_HA
+         goto fail_early;
+     }
+ 
+-    if ( !guest_handle_okay(exch.in.extent_start, exch.in.nr_extents) ||
+-         !guest_handle_okay(exch.out.extent_start, exch.out.nr_extents) )
++    if ( !guest_handle_subrange_okay(exch.in.extent_start, exch.nr_exchanged,
++                                     exch.in.nr_extents - 1) )
+     {
+         rc = -EFAULT;
+         goto fail_early;
+@@ -447,11 +447,27 @@ static long memory_exchange(XEN_GUEST_HA
+     {
+         in_chunk_order  = exch.out.extent_order - exch.in.extent_order;
+         out_chunk_order = 0;
++
++        if ( !guest_handle_subrange_okay(exch.out.extent_start,
++                                         exch.nr_exchanged >> in_chunk_order,
++                                         exch.out.nr_extents - 1) )
++        {
++            rc = -EFAULT;
++            goto fail_early;
++        }
+     }
+     else
+     {
+         in_chunk_order  = 0;
+         out_chunk_order = exch.in.extent_order - exch.out.extent_order;
++
++        if ( !guest_handle_subrange_okay(exch.out.extent_start,
++                                         exch.nr_exchanged << out_chunk_order,
++                                         exch.out.nr_extents - 1) )
++        {
++            rc = -EFAULT;
++            goto fail_early;
++        }
+     }
+ 
+     d = rcu_lock_domain_by_any_id(exch.in.domid);
+--- a/xen/include/asm-x86/x86_64/uaccess.h
++++ b/xen/include/asm-x86/x86_64/uaccess.h
+@@ -29,8 +29,9 @@ extern void *xlat_malloc(unsigned long *
+ /*
+  * Valid if in +ve half of 48-bit address space, or above Xen-reserved area.
+  * This is also valid for range checks (addr, addr+size). As long as the
+- * start address is outside the Xen-reserved area then we will access a
+- * non-canonical address (and thus fault) before ever reaching VIRT_START.
++ * start address is outside the Xen-reserved area, sequential accesses
++ * (starting at addr) will hit a non-canonical address (and thus fault)
++ * before ever reaching VIRT_START.
+  */
+ #define __addr_ok(addr) \
+     (((unsigned long)(addr) < (1UL<<47)) || \
+@@ -40,7 +41,8 @@ extern void *xlat_malloc(unsigned long *
+     (__addr_ok(addr) || is_compat_arg_xlat_range(addr, size))
+ 
+ #define array_access_ok(addr, count, size) \
+-    (access_ok(addr, (count)*(size)))
++    (likely(((count) ?: 0UL) < (~0UL / (size))) && \
++     access_ok(addr, (count) * (size)))
+ 
+ #define __compat_addr_ok(d, addr) \
+     ((unsigned long)(addr) < HYPERVISOR_COMPAT_VIRT_START(d))