On Wed, Apr 23, 2014 at 06:04:45PM -0300, Marcelo Tosatti wrote:
>
> Invariant TSC documentation mentions that "invariant TSC will run at a
> constant rate in all ACPI P-, C-. and T-states".
>
> This is not the case if migration to a host with different TSC frequency
> is allowed, or if savevm is performed. So block migration/savevm.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
>
[...]
> @@ -702,6 +706,16 @@ int kvm_arch_init_vcpu(CPUState *cs)
> !!(c->ecx & CPUID_EXT_SMX);
> }
>
> + c = cpuid_find_entry(&cpuid_data.cpuid, 0x80000007, 0);
> + if (c && (c->edx & 1<<8) && invtsc_mig_blocker == NULL) {
> + /* for migration */
> + error_set(&invtsc_mig_blocker,
> + QERR_DEVICE_FEATURE_BLOCKS_MIGRATION, "invtsc", "cpu");
> + migrate_add_blocker(invtsc_mig_blocker);
> + /* for savevm */
> + vmstate_x86_cpu.unmigratable = 1;
Did you ensure this will always happen before vmstate_register() is
called for vmstate_x86_cpu? I believe kvm_arch_init_vcpu() is called a
long long time after device_set_realized() (which is where
vmstate_register() is called for DeviceState objects).
--
Eduardo
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