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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
Download patch file Download diff file Expand all files Collapse all files

3
include/hw/i386/pc.h
View file

@ -118,6 +118,9 @@ struct PCMachineClass {
/* use PVH to load kernels that support this feature */
bool pvh_enabled;
/* create kvmclock device even when KVM PV features are not exposed */
bool kvmclock_create_always;
};
#define TYPE_PC_MACHINE "generic-pc-machine"

4
include/hw/kvm/clock.h
View file

@ -15,11 +15,11 @@
#ifdef CONFIG_KVM
void kvmclock_create(void);
void kvmclock_create(bool create_always);
#else /* CONFIG_KVM */
static inline void kvmclock_create(void)
static inline void kvmclock_create(bool create_always)
{
}