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| author | Michael Chapman <mike@very.puzzling.org> | 2018-04-06 15:34:06 +1000 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-04-09 16:36:39 +0200 |
| commit | c2b01cfec1f1426d95c27abacc3ea5b5fbb9a57e (patch) | |
| tree | 8b70046af10290f8a0d5a4e9290ad2684795dd16 | |
| parent | 4968a2c6edb7b46b127c19a8426575d23b55ab1f (diff) | |
| download | qemu-c2b01cfec1f1426d95c27abacc3ea5b5fbb9a57e.tar.gz | |
kvmclock: fix clock_is_reliable on migration from QEMU < 2.9
When migrating from a pre-2.9 QEMU, no clock_is_reliable flag is
transferred. We should assume that the source host has an unreliable
KVM_GET_CLOCK, rather than using whatever was determined locally, to
ensure that any drift from the TSC-based value calculated by the guest
is corrected.
Signed-off-by: Michael Chapman <mike@very.puzzling.org>
Message-Id: <20180406053406.774-1-mike@very.puzzling.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | hw/i386/kvm/clock.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 1707434db3..7dac319403 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -242,6 +242,19 @@ static const VMStateDescription kvmclock_reliable_get_clock = { }; /* + * When migrating, assume the source has an unreliable + * KVM_GET_CLOCK unless told otherwise. + */ +static int kvmclock_pre_load(void *opaque) +{ + KVMClockState *s = opaque; + + s->clock_is_reliable = false; + + return 0; +} + +/* * When migrating, read the clock just before migration, * so that the guest clock counts during the events * between: @@ -268,6 +281,7 @@ static const VMStateDescription kvmclock_vmsd = { .name = "kvmclock", .version_id = 1, .minimum_version_id = 1, + .pre_load = kvmclock_pre_load, .pre_save = kvmclock_pre_save, .fields = (VMStateField[]) { VMSTATE_UINT64(clock, KVMClockState), |