* [PATCH] KVM: LAPIC: Disarm LAPIC timer includes pending timer around TSC deadline switch
@ 2022-05-10 9:36 Wanpeng Li
2022-05-10 13:43 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Wanpeng Li @ 2022-05-10 9:36 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
From: Wanpeng Li <wanpengli@tencent.com>
The timer is disarmed when switching between TSC deadline and other modes,
however, the pending timer is still in-flight, so let's accurately set
everything to a disarmed state.
Fixes: 4427593258 (KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch)
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/lapic.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 66b0eb0bda94..0274d17d91c2 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1562,6 +1562,7 @@ static void apic_update_lvtt(struct kvm_lapic *apic)
kvm_lapic_set_reg(apic, APIC_TMICT, 0);
apic->lapic_timer.period = 0;
apic->lapic_timer.tscdeadline = 0;
+ atomic_set(&apic->lapic_timer.pending, 0);
}
apic->lapic_timer.timer_mode = timer_mode;
limit_periodic_timer_frequency(apic);
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: LAPIC: Disarm LAPIC timer includes pending timer around TSC deadline switch
2022-05-10 9:36 [PATCH] KVM: LAPIC: Disarm LAPIC timer includes pending timer around TSC deadline switch Wanpeng Li
@ 2022-05-10 13:43 ` Sean Christopherson
2022-05-11 2:42 ` Wanpeng Li
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2022-05-10 13:43 UTC (permalink / raw)
To: Wanpeng Li
Cc: linux-kernel, kvm, Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
On Tue, May 10, 2022, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> The timer is disarmed when switching between TSC deadline and other modes,
> however, the pending timer is still in-flight, so let's accurately set
> everything to a disarmed state.
>
> Fixes: 4427593258 (KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch)
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> arch/x86/kvm/lapic.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 66b0eb0bda94..0274d17d91c2 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1562,6 +1562,7 @@ static void apic_update_lvtt(struct kvm_lapic *apic)
> kvm_lapic_set_reg(apic, APIC_TMICT, 0);
> apic->lapic_timer.period = 0;
> apic->lapic_timer.tscdeadline = 0;
> + atomic_set(&apic->lapic_timer.pending, 0);
What about doing this in cancel_apic_timer()? That seems to be a more natural
place to clear pending. It's somewhat redundant since the other two callers of
cancel_apic_timer() start the timer immediately after, i.e. clear pending anyways,
but IMO it's odd to leave pending set when canceling the timer.
> }
> apic->lapic_timer.timer_mode = timer_mode;
> limit_periodic_timer_frequency(apic);
> --
> 2.25.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: LAPIC: Disarm LAPIC timer includes pending timer around TSC deadline switch
2022-05-10 13:43 ` Sean Christopherson
@ 2022-05-11 2:42 ` Wanpeng Li
0 siblings, 0 replies; 3+ messages in thread
From: Wanpeng Li @ 2022-05-11 2:42 UTC (permalink / raw)
To: Sean Christopherson
Cc: LKML, kvm, Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
On Tue, 10 May 2022 at 21:43, Sean Christopherson <seanjc@google.com> wrote:
>
> On Tue, May 10, 2022, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@tencent.com>
> >
> > The timer is disarmed when switching between TSC deadline and other modes,
> > however, the pending timer is still in-flight, so let's accurately set
> > everything to a disarmed state.
> >
> > Fixes: 4427593258 (KVM: x86: thoroughly disarm LAPIC timer around TSC deadline switch)
> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> > ---
> > arch/x86/kvm/lapic.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > index 66b0eb0bda94..0274d17d91c2 100644
> > --- a/arch/x86/kvm/lapic.c
> > +++ b/arch/x86/kvm/lapic.c
> > @@ -1562,6 +1562,7 @@ static void apic_update_lvtt(struct kvm_lapic *apic)
> > kvm_lapic_set_reg(apic, APIC_TMICT, 0);
> > apic->lapic_timer.period = 0;
> > apic->lapic_timer.tscdeadline = 0;
> > + atomic_set(&apic->lapic_timer.pending, 0);
>
> What about doing this in cancel_apic_timer()? That seems to be a more natural
> place to clear pending. It's somewhat redundant since the other two callers of
> cancel_apic_timer() start the timer immediately after, i.e. clear pending anyways,
> but IMO it's odd to leave pending set when canceling the timer.
Do it in v2.
Wanpeng
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-05-11 2:47 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-05-10 9:36 [PATCH] KVM: LAPIC: Disarm LAPIC timer includes pending timer around TSC deadline switch Wanpeng Li
2022-05-10 13:43 ` Sean Christopherson
2022-05-11 2:42 ` Wanpeng Li
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox