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authorSamuel Mendoza-Jonas <sam.mj@au1.ibm.com>2014-11-17 15:12:28 +1100
committerAlexander Graf <agraf@suse.de>2015-01-07 16:16:26 +0100
commit01a579729b2e614bd02b25c8504976eeecb64eff (patch)
treef5ce4284c32e0460ece5346ce914598e65f0ea3c /hw
parente094c4c12f33a1c965f5af02f33968a337348739 (diff)
spapr: Fix stale HTAB during live migration (KVM)
If a guest reboots during a running migration, changes to the hash page table are not necessarily updated on the destination. Opening a new file descriptor to the HTAB forces the migration handler to resend the entire table. Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'hw')
-rw-r--r--hw/ppc/spapr.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 08401e0fde..869b72125a 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -833,6 +833,11 @@ static void spapr_reset_htab(sPAPREnvironment *spapr)
/* Kernel handles htab, we don't need to allocate one */
spapr->htab_shift = shift;
kvmppc_kern_htab = true;
+
+ /* Tell readers to update their file descriptor */
+ if (spapr->htab_fd >= 0) {
+ spapr->htab_fd_stale = true;
+ }
} else {
if (!spapr->htab) {
/* Allocate an htab if we don't yet have one */
@@ -867,6 +872,28 @@ static int find_unknown_sysbus_device(SysBusDevice *sbdev, void *opaque)
return 0;
}
+/*
+ * A guest reset will cause spapr->htab_fd to become stale if being used.
+ * Reopen the file descriptor to make sure the whole HTAB is properly read.
+ */
+static int spapr_check_htab_fd(sPAPREnvironment *spapr)
+{
+ int rc = 0;
+
+ if (spapr->htab_fd_stale) {
+ close(spapr->htab_fd);
+ spapr->htab_fd = kvmppc_get_htab_fd(false);
+ if (spapr->htab_fd < 0) {
+ error_report("Unable to open fd for reading hash table from KVM: "
+ "%s", strerror(errno));
+ rc = -1;
+ }
+ spapr->htab_fd_stale = false;
+ }
+
+ return rc;
+}
+
static void ppc_spapr_reset(void)
{
PowerPCCPU *first_ppc_cpu;
@@ -1005,6 +1032,7 @@ static int htab_save_setup(QEMUFile *f, void *opaque)
assert(kvm_enabled());
spapr->htab_fd = kvmppc_get_htab_fd(false);
+ spapr->htab_fd_stale = false;
if (spapr->htab_fd < 0) {
fprintf(stderr, "Unable to open fd for reading hash table from KVM: %s\n",
strerror(errno));
@@ -1157,6 +1185,11 @@ static int htab_save_iterate(QEMUFile *f, void *opaque)
if (!spapr->htab) {
assert(kvm_enabled());
+ rc = spapr_check_htab_fd(spapr);
+ if (rc < 0) {
+ return rc;
+ }
+
rc = kvmppc_save_htab(f, spapr->htab_fd,
MAX_KVM_BUF_SIZE, MAX_ITERATION_NS);
if (rc < 0) {
@@ -1188,6 +1221,11 @@ static int htab_save_complete(QEMUFile *f, void *opaque)
assert(kvm_enabled());
+ rc = spapr_check_htab_fd(spapr);
+ if (rc < 0) {
+ return rc;
+ }
+
rc = kvmppc_save_htab(f, spapr->htab_fd, MAX_KVM_BUF_SIZE, -1);
if (rc < 0) {
return rc;