> On 12 Apr 2019, at 23:18, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote:
>
> ...now that VMX's preemption timer, i.e. the hv_timer, also adjusts its
> programmed time based on lapic_timer_advance_ns. Without the delay, a
> guest can see a timer interrupt arrive before the requested time when
> KVM is using the hv_timer to emulate the guest's interrupt.
>
> Fixes: c5ce8235cffa0 ("KVM: VMX: Optimize tscdeadline timer latency")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Cc: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Nice catch.
Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx>
> ---
> arch/x86/kvm/lapic.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index c43cd26f040b..1d649a2af04c 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1455,7 +1455,7 @@ static void apic_timer_expired(struct kvm_lapic *apic)
> if (swait_active(q))
> swake_up_one(q);
>
> - if (apic_lvtt_tscdeadline(apic))
> + if (apic_lvtt_tscdeadline(apic) || ktimer->hv_timer_in_use)
> ktimer->expired_tscdeadline = ktimer->tscdeadline;
> }
>
> --
> 2.21.0
>
