On 06/04/2018 07:34, Michael Chapman wrote:
> 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 <m...@very.puzzling.org>
> ---
> Resent due to missing CCs.
>
> hw/i386/kvm/clock.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> 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
> @@ -241,6 +241,19 @@ 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
> @@ -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),
>
Queued, thanks.
Paolo
