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authorMaxiwell S. Garcia <maxiwell@linux.ibm.com>2019-08-29 18:07:11 -0300
committerEduardo Habkost <ehabkost@redhat.com>2019-09-03 14:39:46 -0300
commit417332494602e3edadfae3b759a29fa0bb96223f (patch)
treed9af786c08584f1bb97a7a1d76606e013ca4defe /hw/i386/kvm
parentc6c1bb89fb46f3b88f832e654cf5a6f7941aac51 (diff)
migration: Do not re-read the clock on pre_save in case of paused guest
The clock move makes the guest knows about the paused time between the 'stop' and 'migrate' commands. This is an issue in an already-paused VM because some side effects, like process stalls, could happen after migration. So, this patch checks the runstate of guest in the pre_save handler and do not re-reads the clock in case of paused state (cold migration). Signed-off-by: Maxiwell S. Garcia <maxiwell@linux.ibm.com> Message-Id: <20190829210711.6570-1-maxiwell@linux.ibm.com> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Diffstat (limited to 'hw/i386/kvm')
-rw-r--r--hw/i386/kvm/clock.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 80c133a724..2c59b6894b 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -41,6 +41,9 @@ typedef struct KVMClockState {
uint64_t clock;
bool clock_valid;
+ /* whether the 'clock' value was obtained in the 'paused' state */
+ bool runstate_paused;
+
/* whether machine type supports reliable KVM_GET_CLOCK */
bool mach_use_reliable_get_clock;
@@ -202,6 +205,8 @@ static void kvmclock_vm_state_change(void *opaque, int running,
return;
}
+ s->runstate_paused = runstate_check(RUN_STATE_PAUSED);
+
kvm_synchronize_all_tsc();
kvm_update_clock(s);
@@ -260,9 +265,9 @@ static int kvmclock_pre_load(void *opaque)
}
/*
- * When migrating, read the clock just before migration,
- * so that the guest clock counts during the events
- * between:
+ * When migrating a running guest, read the clock just
+ * before migration, so that the guest clock counts
+ * during the events between:
*
* * vm_stop()
* *
@@ -277,7 +282,9 @@ static int kvmclock_pre_save(void *opaque)
{
KVMClockState *s = opaque;
- kvm_update_clock(s);
+ if (!s->runstate_paused) {
+ kvm_update_clock(s);
+ }
return 0;
}