Merge tag 'xenfv-2' of git://git.infradead.org/users/dwmw2/qemu into staging

Enable PV backends with Xen/KVM emulation

This is phase 2, following on from the basic platform support which was
already merged.

 • Add a simple single-tenant internal XenStore implementation
 • Indirect Xen gnttab/evtchn/foreignmem/xenstore through operations table
 • Provide emulated back ends for Xen operations
 • Header cleanups to allow PV back ends to build without Xen itself
 • Enable PV back ends in emulated mode
 • Documentation update

Tested-by: Paul Durrant <paul@xen.org>
... on real Xen (master branch, 4.18) with a Debian guest.

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# gpg: Signature made Tue 07 Mar 2023 22:32:28 GMT
# gpg:                using RSA key 314B08ACD0DE481133A5F2869BE980FD0AC01544
# gpg:                issuer "dwmw@amazon.co.uk"
# gpg: Good signature from "David Woodhouse <dwmw@amazon.co.uk>" [unknown]
# gpg:                 aka "David Woodhouse <dwmw@amazon.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 314B 08AC D0DE 4811 33A5  F286 9BE9 80FD 0AC0 1544

* tag 'xenfv-2' of git://git.infradead.org/users/dwmw2/qemu: (27 commits)
  docs: Update Xen-on-KVM documentation for PV disk support
  MAINTAINERS: Add entry for Xen on KVM emulation
  i386/xen: Initialize Xen backends from pc_basic_device_init() for emulation
  hw/xen: Implement soft reset for emulated gnttab
  hw/xen: Map guest XENSTORE_PFN grant in emulated Xenstore
  hw/xen: Add emulated implementation of XenStore operations
  hw/xen: Add emulated implementation of grant table operations
  hw/xen: Hook up emulated implementation for event channel operations
  hw/xen: Only advertise ring-page-order for xen-block if gnttab supports it
  hw/xen: Avoid crash when backend watch fires too early
  hw/xen: Build PV backend drivers for CONFIG_XEN_BUS
  hw/xen: Rename xen_common.h to xen_native.h
  hw/xen: Use XEN_PAGE_SIZE in PV backend drivers
  hw/xen: Move xenstore_store_pv_console_info to xen_console.c
  hw/xen: Add xenstore operations to allow redirection to internal emulation
  hw/xen: Add foreignmem operations to allow redirection to internal emulation
  hw/xen: Pass grant ref to gnttab unmap operation
  hw/xen: Add gnttab operations to allow redirection to internal emulation
  hw/xen: Add evtchn operations to allow redirection to internal emulation
  hw/xen: Create initial XenStore nodes
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

7 files changed, 458 insertions, 126 deletions

diff --git a/include/hw/xen/xen-bus-helper.h b/include/hw/xen/xen-bus-helper.h
index 8782f30550..d8dcc2f010 100644
--- a/include/hw/xen/xen-bus-helper.h
+++ b/include/hw/xen/xen-bus-helper.h
@@ -8,40 +8,40 @@
 #ifndef HW_XEN_BUS_HELPER_H
 #define HW_XEN_BUS_HELPER_H
 
-#include "hw/xen/xen_common.h"
+#include "hw/xen/xen_backend_ops.h"
 
 const char *xs_strstate(enum xenbus_state state);
 
-void xs_node_create(struct xs_handle *xsh,  xs_transaction_t tid,
-                    const char *node, struct xs_permissions perms[],
-                    unsigned int nr_perms, Error **errp);
-void xs_node_destroy(struct xs_handle *xsh,  xs_transaction_t tid,
+void xs_node_create(struct qemu_xs_handle *h,  xs_transaction_t tid,
+                    const char *node, unsigned int owner, unsigned int domid,
+                    unsigned int perms, Error **errp);
+void xs_node_destroy(struct qemu_xs_handle *h,  xs_transaction_t tid,
                      const char *node, Error **errp);
 
 /* Write to node/key unless node is empty, in which case write to key */
-void xs_node_vprintf(struct xs_handle *xsh,  xs_transaction_t tid,
+void xs_node_vprintf(struct qemu_xs_handle *h,  xs_transaction_t tid,
                      const char *node, const char *key, Error **errp,
                      const char *fmt, va_list ap)
     G_GNUC_PRINTF(6, 0);
-void xs_node_printf(struct xs_handle *xsh,  xs_transaction_t tid,
+void xs_node_printf(struct qemu_xs_handle *h,  xs_transaction_t tid,
                     const char *node, const char *key, Error **errp,
                     const char *fmt, ...)
     G_GNUC_PRINTF(6, 7);
 
 /* Read from node/key unless node is empty, in which case read from key */
-int xs_node_vscanf(struct xs_handle *xsh,  xs_transaction_t tid,
+int xs_node_vscanf(struct qemu_xs_handle *h,  xs_transaction_t tid,
                    const char *node, const char *key, Error **errp,
                    const char *fmt, va_list ap)
     G_GNUC_SCANF(6, 0);
-int xs_node_scanf(struct xs_handle *xsh,  xs_transaction_t tid,
+int xs_node_scanf(struct qemu_xs_handle *h,  xs_transaction_t tid,
                   const char *node, const char *key, Error **errp,
                   const char *fmt, ...)
     G_GNUC_SCANF(6, 7);
 
 /* Watch node/key unless node is empty, in which case watch key */
-void xs_node_watch(struct xs_handle *xsh, const char *node, const char *key,
-                   char *token, Error **errp);
-void xs_node_unwatch(struct xs_handle *xsh, const char *node, const char *key,
-                     const char *token, Error **errp);
+struct qemu_xs_watch *xs_node_watch(struct qemu_xs_handle *h, const char *node,
+                                    const char *key, xs_watch_fn fn,
+                                    void *opaque, Error **errp);
+void xs_node_unwatch(struct qemu_xs_handle *h, struct qemu_xs_watch *w);
 
 #endif /* HW_XEN_BUS_HELPER_H */
diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h
index 4d966a2dbb..f435898164 100644
--- a/include/hw/xen/xen-bus.h
+++ b/include/hw/xen/xen-bus.h
@@ -8,31 +8,25 @@
 #ifndef HW_XEN_BUS_H
 #define HW_XEN_BUS_H
 
-#include "hw/xen/xen_common.h"
+#include "hw/xen/xen_backend_ops.h"
 #include "hw/sysbus.h"
 #include "qemu/notify.h"
 #include "qom/object.h"
 
-typedef void (*XenWatchHandler)(void *opaque);
-
-typedef struct XenWatchList XenWatchList;
-typedef struct XenWatch XenWatch;
 typedef struct XenEventChannel XenEventChannel;
 
 struct XenDevice {
     DeviceState qdev;
     domid_t frontend_id;
     char *name;
-    struct xs_handle *xsh;
-    XenWatchList *watch_list;
+    struct qemu_xs_handle *xsh;
     char *backend_path, *frontend_path;
     enum xenbus_state backend_state, frontend_state;
     Notifier exit;
-    XenWatch *backend_state_watch, *frontend_state_watch;
+    struct qemu_xs_watch *backend_state_watch, *frontend_state_watch;
     bool backend_online;
-    XenWatch *backend_online_watch;
+    struct qemu_xs_watch *backend_online_watch;
     xengnttab_handle *xgth;
-    bool feature_grant_copy;
     bool inactive;
     QLIST_HEAD(, XenEventChannel) event_channels;
     QLIST_ENTRY(XenDevice) list;
@@ -64,10 +58,9 @@ OBJECT_DECLARE_TYPE(XenDevice, XenDeviceClass, XEN_DEVICE)
 struct XenBus {
     BusState qbus;
     domid_t backend_id;
-    struct xs_handle *xsh;
-    XenWatchList *watch_list;
+    struct qemu_xs_handle *xsh;
     unsigned int backend_types;
-    XenWatch **backend_watch;
+    struct qemu_xs_watch **backend_watch;
     QLIST_HEAD(, XenDevice) inactive_devices;
 };
 
@@ -102,7 +95,7 @@ void xen_device_set_max_grant_refs(XenDevice *xendev, unsigned int nr_refs,
 void *xen_device_map_grant_refs(XenDevice *xendev, uint32_t *refs,
                                 unsigned int nr_refs, int prot,
                                 Error **errp);
-void xen_device_unmap_grant_refs(XenDevice *xendev, void *map,
+void xen_device_unmap_grant_refs(XenDevice *xendev, void *map, uint32_t *refs,
                                  unsigned int nr_refs, Error **errp);
 
 typedef struct XenDeviceGrantCopySegment {
diff --git a/include/hw/xen/xen-legacy-backend.h b/include/hw/xen/xen-legacy-backend.h
index e31cd3a068..6c307c5f2c 100644
--- a/include/hw/xen/xen-legacy-backend.h
+++ b/include/hw/xen/xen-legacy-backend.h
@@ -1,7 +1,7 @@
 #ifndef HW_XEN_LEGACY_BACKEND_H
 #define HW_XEN_LEGACY_BACKEND_H
 
-#include "hw/xen/xen_common.h"
+#include "hw/xen/xen_backend_ops.h"
 #include "hw/xen/xen_pvdev.h"
 #include "net/net.h"
 #include "qom/object.h"
@@ -15,7 +15,7 @@ DECLARE_INSTANCE_CHECKER(XenLegacyDevice, XENBACKEND,
                          TYPE_XENBACKEND)
 
 /* variables */
-extern struct xs_handle *xenstore;
+extern struct qemu_xs_handle *xenstore;
 extern const char *xen_protocol;
 extern DeviceState *xen_sysdev;
 extern BusState *xen_sysbus;
@@ -30,9 +30,6 @@ int xenstore_write_be_int64(struct XenLegacyDevice *xendev, const char *node,
 char *xenstore_read_be_str(struct XenLegacyDevice *xendev, const char *node);
 int xenstore_read_be_int(struct XenLegacyDevice *xendev, const char *node,
                          int *ival);
-void xenstore_update_fe(char *watch, struct XenLegacyDevice *xendev);
-void xenstore_update_be(char *watch, char *type, int dom,
-                        struct XenDevOps *ops);
 char *xenstore_read_fe_str(struct XenLegacyDevice *xendev, const char *node);
 int xenstore_read_fe_int(struct XenLegacyDevice *xendev, const char *node,
                          int *ival);
@@ -51,18 +48,7 @@ void xen_be_set_max_grant_refs(struct XenLegacyDevice *xendev,
 void *xen_be_map_grant_refs(struct XenLegacyDevice *xendev, uint32_t *refs,
                             unsigned int nr_refs, int prot);
 void xen_be_unmap_grant_refs(struct XenLegacyDevice *xendev, void *ptr,
-                             unsigned int nr_refs);
-
-typedef struct XenGrantCopySegment {
-    union {
-        void *virt;
-        struct {
-            uint32_t ref;
-            off_t offset;
-        } foreign;
-    } source, dest;
-    size_t len;
-} XenGrantCopySegment;
+                             uint32_t *refs, unsigned int nr_refs);
 
 int xen_be_copy_grant_refs(struct XenLegacyDevice *xendev,
                            bool to_domain, XenGrantCopySegment segs[],
@@ -75,9 +61,9 @@ static inline void *xen_be_map_grant_ref(struct XenLegacyDevice *xendev,
 }
 
 static inline void xen_be_unmap_grant_ref(struct XenLegacyDevice *xendev,
-                                          void *ptr)
+                                          void *ptr, uint32_t ref)
 {
-    return xen_be_unmap_grant_refs(xendev, ptr, 1);
+    return xen_be_unmap_grant_refs(xendev, ptr, &ref, 1);
 }
 
 /* actual backend drivers */
diff --git a/include/hw/xen/xen.h b/include/hw/xen/xen.h
index 03983939f9..2bd8ec742d 100644
--- a/include/hw/xen/xen.h
+++ b/include/hw/xen/xen.h
@@ -8,15 +8,21 @@
 #define QEMU_HW_XEN_H
 
 /*
- * As a temporary measure while the headers are being untangled, define
- * __XEN_TOOLS__ here before any Xen headers are included. Otherwise, if
- * the Xen toolstack library headers are later included, they will find
- * some of the "internal" definitions missing and the build will fail. In
- * later commits, we'll end up with a rule that the native libraries have
- * to be included first, which will ensure that the libraries get the
- * version of Xen libraries that they expect.
+ * C files using Xen toolstack libraries will have included those headers
+ * already via xen_native.h, and having __XEM_TOOLS__ defined will have
+ * automatically set __XEN_INTERFACE_VERSION__ to the latest supported
+ * by the *system* Xen headers which were transitively included.
+ *
+ * C files which are part of the internal emulation, and which did not
+ * include xen_native.h, may need this defined so that the Xen headers
+ * imported to include/hw/xen/interface/ will expose the appropriate API
+ * version.
+ *
+ * This is why there's a rule that xen_native.h must be included first.
  */
-#define __XEN_TOOLS__ 1
+#ifndef __XEN_INTERFACE_VERSION__
+#define __XEN_INTERFACE_VERSION__ 0x00040e00
+#endif
 
 #include "exec/cpu-common.h"
 
@@ -39,8 +45,6 @@ int xen_is_pirq_msi(uint32_t msi_data);
 
 qemu_irq *xen_interrupt_controller_init(void);
 
-void xenstore_store_pv_console_info(int i, Chardev *chr);
-
 void xen_register_framebuffer(struct MemoryRegion *mr);
 
 #endif /* QEMU_HW_XEN_H */
diff --git a/include/hw/xen/xen_backend_ops.h b/include/hw/xen/xen_backend_ops.h
new file mode 100644
index 0000000000..90cca85f52
--- /dev/null
+++ b/include/hw/xen/xen_backend_ops.h
@@ -0,0 +1,408 @@
+/*
+ * QEMU Xen backend support
+ *
+ * Copyright © 2022 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Authors: David Woodhouse <dwmw2@infradead.org>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef QEMU_XEN_BACKEND_OPS_H
+#define QEMU_XEN_BACKEND_OPS_H
+
+#include "hw/xen/xen.h"
+#include "hw/xen/interface/xen.h"
+#include "hw/xen/interface/io/xenbus.h"
+
+/*
+ * For the time being, these operations map fairly closely to the API of
+ * the actual Xen libraries, e.g. libxenevtchn. As we complete the migration
+ * from XenLegacyDevice back ends to the new XenDevice model, they may
+ * evolve to slightly higher-level APIs.
+ *
+ * The internal emulations do not emulate the Xen APIs entirely faithfully;
+ * only enough to be used by the Xen backend devices. For example, only one
+ * event channel can be bound to each handle, since that's sufficient for
+ * the device support (only the true Xen HVM backend uses more). And the
+ * behaviour of unmask() and pending() is different too because the device
+ * backends don't care.
+ */
+
+typedef struct xenevtchn_handle xenevtchn_handle;
+typedef int xenevtchn_port_or_error_t;
+typedef uint32_t evtchn_port_t;
+typedef uint16_t domid_t;
+typedef uint32_t grant_ref_t;
+
+#define XEN_PAGE_SHIFT       12
+#define XEN_PAGE_SIZE        (1UL << XEN_PAGE_SHIFT)
+#define XEN_PAGE_MASK        (~(XEN_PAGE_SIZE - 1))
+
+#ifndef xen_rmb
+#define xen_rmb() smp_rmb()
+#endif
+#ifndef xen_wmb
+#define xen_wmb() smp_wmb()
+#endif
+#ifndef xen_mb
+#define xen_mb() smp_mb()
+#endif
+
+struct evtchn_backend_ops {
+    xenevtchn_handle *(*open)(void);
+    int (*bind_interdomain)(xenevtchn_handle *xc, uint32_t domid,
+                            evtchn_port_t guest_port);
+    int (*unbind)(xenevtchn_handle *xc, evtchn_port_t port);
+    int (*close)(struct xenevtchn_handle *xc);
+    int (*get_fd)(struct xenevtchn_handle *xc);
+    int (*notify)(struct xenevtchn_handle *xc, evtchn_port_t port);
+    int (*unmask)(struct xenevtchn_handle *xc, evtchn_port_t port);
+    int (*pending)(struct xenevtchn_handle *xc);
+};
+
+extern struct evtchn_backend_ops *xen_evtchn_ops;
+
+static inline xenevtchn_handle *qemu_xen_evtchn_open(void)
+{
+    if (!xen_evtchn_ops) {
+        return NULL;
+    }
+    return xen_evtchn_ops->open();
+}
+
+static inline int qemu_xen_evtchn_bind_interdomain(xenevtchn_handle *xc,
+                                                   uint32_t domid,
+                                                   evtchn_port_t guest_port)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->bind_interdomain(xc, domid, guest_port);
+}
+
+static inline int qemu_xen_evtchn_unbind(xenevtchn_handle *xc,
+                                         evtchn_port_t port)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->unbind(xc, port);
+}
+
+static inline int qemu_xen_evtchn_close(xenevtchn_handle *xc)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->close(xc);
+}
+
+static inline int qemu_xen_evtchn_fd(xenevtchn_handle *xc)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->get_fd(xc);
+}
+
+static inline int qemu_xen_evtchn_notify(xenevtchn_handle *xc,
+                                         evtchn_port_t port)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->notify(xc, port);
+}
+
+static inline int qemu_xen_evtchn_unmask(xenevtchn_handle *xc,
+                                         evtchn_port_t port)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->unmask(xc, port);
+}
+
+static inline int qemu_xen_evtchn_pending(xenevtchn_handle *xc)
+{
+    if (!xen_evtchn_ops) {
+        return -ENOSYS;
+    }
+    return xen_evtchn_ops->pending(xc);
+}
+
+typedef struct xengntdev_handle xengnttab_handle;
+
+typedef struct XenGrantCopySegment {
+    union {
+        void *virt;
+        struct {
+            uint32_t ref;
+            off_t offset;
+        } foreign;
+    } source, dest;
+    size_t len;
+} XenGrantCopySegment;
+
+#define XEN_GNTTAB_OP_FEATURE_MAP_MULTIPLE  (1U << 0)
+
+struct gnttab_backend_ops {
+    uint32_t features;
+    xengnttab_handle *(*open)(void);
+    int (*close)(xengnttab_handle *xgt);
+    int (*grant_copy)(xengnttab_handle *xgt, bool to_domain, uint32_t domid,
+                      XenGrantCopySegment *segs, uint32_t nr_segs,
+                      Error **errp);
+    int (*set_max_grants)(xengnttab_handle *xgt, uint32_t nr_grants);
+    void *(*map_refs)(xengnttab_handle *xgt, uint32_t count, uint32_t domid,
+                      uint32_t *refs, int prot);
+    int (*unmap)(xengnttab_handle *xgt, void *start_address, uint32_t *refs,
+                 uint32_t count);
+};
+
+extern struct gnttab_backend_ops *xen_gnttab_ops;
+
+static inline bool qemu_xen_gnttab_can_map_multi(void)
+{
+    return xen_gnttab_ops &&
+        !!(xen_gnttab_ops->features & XEN_GNTTAB_OP_FEATURE_MAP_MULTIPLE);
+}
+
+static inline xengnttab_handle *qemu_xen_gnttab_open(void)
+{
+    if (!xen_gnttab_ops) {
+        return NULL;
+    }
+    return xen_gnttab_ops->open();
+}
+
+static inline int qemu_xen_gnttab_close(xengnttab_handle *xgt)
+{
+    if (!xen_gnttab_ops) {
+        return -ENOSYS;
+    }
+    return xen_gnttab_ops->close(xgt);
+}
+
+static inline int qemu_xen_gnttab_grant_copy(xengnttab_handle *xgt,
+                                             bool to_domain, uint32_t domid,
+                                             XenGrantCopySegment *segs,
+                                             uint32_t nr_segs, Error **errp)
+{
+    if (!xen_gnttab_ops) {
+        return -ENOSYS;
+    }
+
+    return xen_gnttab_ops->grant_copy(xgt, to_domain, domid, segs, nr_segs,
+                                      errp);
+}
+
+static inline int qemu_xen_gnttab_set_max_grants(xengnttab_handle *xgt,
+                                                 uint32_t nr_grants)
+{
+    if (!xen_gnttab_ops) {
+        return -ENOSYS;
+    }
+    return xen_gnttab_ops->set_max_grants(xgt, nr_grants);
+}
+
+static inline void *qemu_xen_gnttab_map_refs(xengnttab_handle *xgt,
+                                             uint32_t count, uint32_t domid,
+                                             uint32_t *refs, int prot)
+{
+    if (!xen_gnttab_ops) {
+        return NULL;
+    }
+    return xen_gnttab_ops->map_refs(xgt, count, domid, refs, prot);
+}
+
+static inline int qemu_xen_gnttab_unmap(xengnttab_handle *xgt,
+                                        void *start_address, uint32_t *refs,
+                                        uint32_t count)
+{
+    if (!xen_gnttab_ops) {
+        return -ENOSYS;
+    }
+    return xen_gnttab_ops->unmap(xgt, start_address, refs, count);
+}
+
+struct foreignmem_backend_ops {
+    void *(*map)(uint32_t dom, void *addr, int prot, size_t pages,
+                 xen_pfn_t *pfns, int *errs);
+    int (*unmap)(void *addr, size_t pages);
+};
+
+extern struct foreignmem_backend_ops *xen_foreignmem_ops;
+
+static inline void *qemu_xen_foreignmem_map(uint32_t dom, void *addr, int prot,
+                                            size_t pages, xen_pfn_t *pfns,
+                                            int *errs)
+{
+    if (!xen_foreignmem_ops) {
+        return NULL;
+    }
+    return xen_foreignmem_ops->map(dom, addr, prot, pages, pfns, errs);
+}
+
+static inline int qemu_xen_foreignmem_unmap(void *addr, size_t pages)
+{
+    if (!xen_foreignmem_ops) {
+        return -ENOSYS;
+    }
+    return xen_foreignmem_ops->unmap(addr, pages);
+}
+
+typedef void (*xs_watch_fn)(void *opaque, const char *path);
+
+struct qemu_xs_handle;
+struct qemu_xs_watch;
+typedef uint32_t xs_transaction_t;
+
+#define XBT_NULL 0
+
+#define XS_PERM_NONE  0x00
+#define XS_PERM_READ  0x01
+#define XS_PERM_WRITE 0x02
+
+struct xenstore_backend_ops {
+    struct qemu_xs_handle *(*open)(void);
+    void (*close)(struct qemu_xs_handle *h);
+    char *(*get_domain_path)(struct qemu_xs_handle *h, unsigned int domid);
+    char **(*directory)(struct qemu_xs_handle *h, xs_transaction_t t,
+                        const char *path, unsigned int *num);
+    void *(*read)(struct qemu_xs_handle *h, xs_transaction_t t,
+                  const char *path, unsigned int *len);
+    bool (*write)(struct qemu_xs_handle *h, xs_transaction_t t,
+                  const char *path, const void *data, unsigned int len);
+    bool (*create)(struct qemu_xs_handle *h, xs_transaction_t t,
+                   unsigned int owner, unsigned int domid,
+                   unsigned int perms, const char *path);
+    bool (*destroy)(struct qemu_xs_handle *h, xs_transaction_t t,
+               const char *path);
+    struct qemu_xs_watch *(*watch)(struct qemu_xs_handle *h, const char *path,
+                                   xs_watch_fn fn, void *opaque);
+    void (*unwatch)(struct qemu_xs_handle *h, struct qemu_xs_watch *w);
+    xs_transaction_t (*transaction_start)(struct qemu_xs_handle *h);
+    bool (*transaction_end)(struct qemu_xs_handle *h, xs_transaction_t t,
+                            bool abort);
+};
+
+extern struct xenstore_backend_ops *xen_xenstore_ops;
+
+static inline struct qemu_xs_handle *qemu_xen_xs_open(void)
+{
+    if (!xen_xenstore_ops) {
+        return NULL;
+    }
+    return xen_xenstore_ops->open();
+}
+
+static inline void qemu_xen_xs_close(struct qemu_xs_handle *h)
+{
+    if (!xen_xenstore_ops) {
+        return;
+    }
+    xen_xenstore_ops->close(h);
+}
+
+static inline char *qemu_xen_xs_get_domain_path(struct qemu_xs_handle *h,
+                                                unsigned int domid)
+{
+    if (!xen_xenstore_ops) {
+        return NULL;
+    }
+    return xen_xenstore_ops->get_domain_path(h, domid);
+}
+
+static inline char **qemu_xen_xs_directory(struct qemu_xs_handle *h,
+                                           xs_transaction_t t, const char *path,
+                                           unsigned int *num)
+{
+    if (!xen_xenstore_ops) {
+        return NULL;
+    }
+    return xen_xenstore_ops->directory(h, t, path, num);
+}
+
+static inline void *qemu_xen_xs_read(struct qemu_xs_handle *h,
+                                     xs_transaction_t t, const char *path,
+                                     unsigned int *len)
+{
+    if (!xen_xenstore_ops) {
+        return NULL;
+    }
+    return xen_xenstore_ops->read(h, t, path, len);
+}
+
+static inline bool qemu_xen_xs_write(struct qemu_xs_handle *h,
+                                     xs_transaction_t t, const char *path,
+                                     const void *data, unsigned int len)
+{
+    if (!xen_xenstore_ops) {
+        return false;
+    }
+    return xen_xenstore_ops->write(h, t, path, data, len);
+}
+
+static inline bool qemu_xen_xs_create(struct qemu_xs_handle *h,
+                                      xs_transaction_t t, unsigned int owner,
+                                      unsigned int domid, unsigned int perms,
+                                      const char *path)
+{
+    if (!xen_xenstore_ops) {
+        return false;
+    }
+    return xen_xenstore_ops->create(h, t, owner, domid, perms, path);
+}
+
+static inline bool qemu_xen_xs_destroy(struct qemu_xs_handle *h,
+                                       xs_transaction_t t, const char *path)
+{
+    if (!xen_xenstore_ops) {
+        return false;
+    }
+    return xen_xenstore_ops->destroy(h, t, path);
+}
+
+static inline struct qemu_xs_watch *qemu_xen_xs_watch(struct qemu_xs_handle *h,
+                                                      const char *path,
+                                                      xs_watch_fn fn,
+                                                      void *opaque)
+{
+    if (!xen_xenstore_ops) {
+        return NULL;
+    }
+    return xen_xenstore_ops->watch(h, path, fn, opaque);
+}
+
+static inline void qemu_xen_xs_unwatch(struct qemu_xs_handle *h,
+                                       struct qemu_xs_watch *w)
+{
+    if (!xen_xenstore_ops) {
+        return;
+    }
+    xen_xenstore_ops->unwatch(h, w);
+}
+
+static inline xs_transaction_t qemu_xen_xs_transaction_start(struct qemu_xs_handle *h)
+{
+    if (!xen_xenstore_ops) {
+        return XBT_NULL;
+    }
+    return xen_xenstore_ops->transaction_start(h);
+}
+
+static inline bool qemu_xen_xs_transaction_end(struct qemu_xs_handle *h,
+                                               xs_transaction_t t, bool abort)
+{
+    if (!xen_xenstore_ops) {
+        return false;
+    }
+    return xen_xenstore_ops->transaction_end(h, t, abort);
+}
+
+void setup_xen_backend_ops(void);
+
+#endif /* QEMU_XEN_BACKEND_OPS_H */
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_native.h
index 9a13a756ae..6bcc83baf9 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_native.h
@@ -1,5 +1,9 @@
-#ifndef QEMU_HW_XEN_COMMON_H
-#define QEMU_HW_XEN_COMMON_H
+#ifndef QEMU_HW_XEN_NATIVE_H
+#define QEMU_HW_XEN_NATIVE_H
+
+#ifdef __XEN_INTERFACE_VERSION__
+#error In Xen native files, include xen_native.h before other Xen headers
+#endif
 
 /*
  * If we have new enough libxenctrl then we do not want/need these compat
@@ -12,7 +16,6 @@
 
 #include <xenctrl.h>
 #include <xenstore.h>
-#include "hw/xen/interface/io/xenbus.h"
 
 #include "hw/xen/xen.h"
 #include "hw/pci/pci_device.h"
@@ -28,49 +31,12 @@ extern xc_interface *xen_xc;
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40701
 
 typedef xc_interface xenforeignmemory_handle;
-typedef xc_evtchn xenevtchn_handle;
-typedef xc_gnttab xengnttab_handle;
-typedef evtchn_port_or_error_t xenevtchn_port_or_error_t;
-
-#define xenevtchn_open(l, f) xc_evtchn_open(l, f);
-#define xenevtchn_close(h) xc_evtchn_close(h)
-#define xenevtchn_fd(h) xc_evtchn_fd(h)
-#define xenevtchn_pending(h) xc_evtchn_pending(h)
-#define xenevtchn_notify(h, p) xc_evtchn_notify(h, p)
-#define xenevtchn_bind_interdomain(h, d, p) xc_evtchn_bind_interdomain(h, d, p)
-#define xenevtchn_unmask(h, p) xc_evtchn_unmask(h, p)
-#define xenevtchn_unbind(h, p) xc_evtchn_unbind(h, p)
-
-#define xengnttab_open(l, f) xc_gnttab_open(l, f)
-#define xengnttab_close(h) xc_gnttab_close(h)
-#define xengnttab_set_max_grants(h, n) xc_gnttab_set_max_grants(h, n)
-#define xengnttab_map_grant_ref(h, d, r, p) xc_gnttab_map_grant_ref(h, d, r, p)
-#define xengnttab_unmap(h, a, n) xc_gnttab_munmap(h, a, n)
-#define xengnttab_map_grant_refs(h, c, d, r, p) \
-    xc_gnttab_map_grant_refs(h, c, d, r, p)
-#define xengnttab_map_domain_grant_refs(h, c, d, r, p) \
-    xc_gnttab_map_domain_grant_refs(h, c, d, r, p)
 
 #define xenforeignmemory_open(l, f) xen_xc
 #define xenforeignmemory_close(h)
 
-static inline void *xenforeignmemory_map(xc_interface *h, uint32_t dom,
-                                         int prot, size_t pages,
-                                         const xen_pfn_t arr[/*pages*/],
-                                         int err[/*pages*/])
-{
-    if (err)
-        return xc_map_foreign_bulk(h, dom, prot, arr, err, pages);
-    else
-        return xc_map_foreign_pages(h, dom, prot, arr, pages);
-}
-
-#define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
-
 #else /* CONFIG_XEN_CTRL_INTERFACE_VERSION >= 40701 */
 
-#include <xenevtchn.h>
-#include <xengnttab.h>
 #include <xenforeignmemory.h>
 
 #endif
@@ -660,31 +626,4 @@ static inline int xen_set_ioreq_server_state(domid_t dom,
 
 #endif
 
-/* Xen before 4.8 */
-
-#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 40800
-
-struct xengnttab_grant_copy_segment {
-    union xengnttab_copy_ptr {
-        void *virt;
-        struct {
-            uint32_t ref;
-            uint16_t offset;
-            uint16_t domid;
-        } foreign;
-    } source, dest;
-    uint16_t len;
-    uint16_t flags;
-    int16_t status;
-};
-
-typedef struct xengnttab_grant_copy_segment xengnttab_grant_copy_segment_t;
-
-static inline int xengnttab_grant_copy(xengnttab_handle *xgt, uint32_t count,
-                                       xengnttab_grant_copy_segment_t *segs)
-{
-    return -ENOSYS;
-}
-#endif
-
-#endif /* QEMU_HW_XEN_COMMON_H */
+#endif /* QEMU_HW_XEN_NATIVE_H */
diff --git a/include/hw/xen/xen_pvdev.h b/include/hw/xen/xen_pvdev.h
index 7cd4bc2b82..ddad4b9f36 100644
--- a/include/hw/xen/xen_pvdev.h
+++ b/include/hw/xen/xen_pvdev.h
@@ -1,7 +1,9 @@
 #ifndef QEMU_HW_XEN_PVDEV_H
 #define QEMU_HW_XEN_PVDEV_H
 
-#include "hw/xen/xen_common.h"
+#include "hw/qdev-core.h"
+#include "hw/xen/xen_backend_ops.h"
+
 /* ------------------------------------------------------------- */
 
 #define XEN_BUFSIZE 1024
@@ -38,6 +40,7 @@ struct XenLegacyDevice {
     char               name[64];
     int                debug;
 
+    struct qemu_xs_watch *watch;
     enum xenbus_state  be_state;
     enum xenbus_state  fe_state;
     int                online;
@@ -63,7 +66,6 @@ int xenstore_write_int64(const char *base, const char *node, int64_t ival);
 char *xenstore_read_str(const char *base, const char *node);
 int xenstore_read_int(const char *base, const char *node, int *ival);
 int xenstore_read_uint64(const char *base, const char *node, uint64_t *uval);
-void xenstore_update(void *unused);
 
 const char *xenbus_strstate(enum xenbus_state state);