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.dam...@blade-group.com>
Suggested-by: Paolo Bonzini <pbonz...@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
---
hw/i386/kvm/clock.c | 6 +-----
target/i386/kvm.c | 5 +++++
target/i386/kvm_i386.h | 1 +
3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 64283358f91d..526c9ea5172b 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -330,11 +330,7 @@ static const TypeInfo kvmclock_info = {
/* Note: Must be called after VCPU initialization. */
void kvmclock_create(void)
{
- X86CPU *cpu = X86_CPU(first_cpu);
-
- if (kvm_enabled() &&
- cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
- (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
+ if (kvm_enabled() && kvm_has_adjust_clock()) {
sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
}
}
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 4a8b3a41c1bc..20b31b65307b 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -143,6 +143,11 @@ bool kvm_has_adjust_clock_stable(void)
return (ret == KVM_CLOCK_TSC_STABLE);
}
+bool kvm_has_adjust_clock(void)
+{
+ return kvm_check_extension(kvm_state, KVM_CAP_ADJUST_CLOCK);
+}
+
bool kvm_has_exception_payload(void)
{
return has_exception_payload;
diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index 064b8798a26c..0fce4e51d2d6 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -34,6 +34,7 @@
bool kvm_allows_irq0_override(void);
bool kvm_has_smm(void);
+bool kvm_has_adjust_clock(void);
bool kvm_has_adjust_clock_stable(void);
bool kvm_has_exception_payload(void);
void kvm_synchronize_all_tsc(void);
--
2.25.4
