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target/i386: always create kvmclock device

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QEMU's kvmclock device is only created when KVM PV feature bits for
kvmclock (KVM_FEATURE_CLOCKSOURCE/KVM_FEATURE_CLOCKSOURCE2) are
exposed to the guest. With 'kvm=off' cpu flag the device is not
created and we don't call KVM_GET_CLOCK/KVM_SET_CLOCK upon migration.
It was reported that without these call at least Hyper-V TSC page
clocksouce (which can be enabled independently) gets broken after
migration.

Switch to creating kvmclock QEMU device unconditionally, it seems
to always make sense to call KVM_GET_CLOCK/KVM_SET_CLOCK on migration.
Use KVM_CAP_ADJUST_CLOCK check instead of CPUID feature bits.

Reported-by: Antoine Damhet <antoine.damhet@blade-group.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200922151934.899555-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2020-09-22 17:19:34 +02:00 • committed by Paolo Bonzini
parent 6615be072d
commit 8700a98443
9 changed files with 27 additions and 8 deletions
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7
hw/i386/kvm/clock.c
View file

@ -329,11 +329,14 @@ static const TypeInfo kvmclock_info = {
};
/* Note: Must be called after VCPU initialization. */
void kvmclock_create(void)
void kvmclock_create(bool create_always)
{
X86CPU *cpu = X86_CPU(first_cpu);
if (kvm_enabled() &&
if (!kvm_enabled() || !kvm_has_adjust_clock())
return;
if (create_always ||
cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
(1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);