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SubjectRe: [PATCH] kvm: clear kvmclock MSR on reset
Date
Paolo Bonzini <pbonzini@redhat.com> writes:

> After resetting the vCPU, the kvmclock MSR keeps the previous value but it is
> not enabled. This can be confusing, so fix it.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> arch/x86/kvm/x86.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f26f8be4e621..a55252c69118 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2533,6 +2533,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
> static void kvmclock_reset(struct kvm_vcpu *vcpu)
> {
> vcpu->arch.pv_time_enabled = false;
> + vcpu->arch.time = 0;
> }
>
> static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu, bool invalidate_gpa)
> @@ -2698,8 +2699,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> case MSR_KVM_SYSTEM_TIME: {
> struct kvm_arch *ka = &vcpu->kvm->arch;
>
> - kvmclock_reset(vcpu);
> -
> if (vcpu->vcpu_id == 0 && !msr_info->host_initiated) {
> bool tmp = (msr == MSR_KVM_SYSTEM_TIME);
>
> @@ -2713,14 +2712,13 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> kvm_make_request(KVM_REQ_GLOBAL_CLOCK_UPDATE, vcpu);
>
> /* we verify if the enable bit is set... */
> + vcpu->arch.pv_time_enabled = false;
> if (!(data & 1))
> break;
>
> if (kvm_gfn_to_hva_cache_init(vcpu->kvm,
> &vcpu->arch.pv_time, data & ~1ULL,
> sizeof(struct pvclock_vcpu_time_info)))
> - vcpu->arch.pv_time_enabled = false;
> - else
> vcpu->arch.pv_time_enabled = true;

Hm, are you sure you didn't want to write !kvm_gfn_to_hva_cache_init()?

>
> break;

--
Vitaly

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