From: Sean Christopherson <seanjc@google.com>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH 1/2] KVM: LAPIC: write 0 to TMICT should also cancel vmx-preemption timer
Date: Thu, 3 Jun 2021 15:20:07 +0000 [thread overview]
Message-ID: <YLjzJ59HPqGfhhvm@google.com> (raw)
In-Reply-To: <1622710841-76604-1-git-send-email-wanpengli@tencent.com>
On Thu, Jun 03, 2021, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> According to the SDM 10.5.4.1:
>
> A write of 0 to the initial-count register effectively stops the local
> APIC timer, in both one-shot and periodic mode.
>
> The lapic timer oneshot/periodic mode which is emulated by vmx-preemption
> timer doesn't stop since vmx->hv_deadline_tsc is still set.
But the VMX preemption timer is only used for deadline, never for oneshot or
periodic. Am I missing something?
static bool start_hv_timer(struct kvm_lapic *apic)
{
struct kvm_timer *ktimer = &apic->lapic_timer;
struct kvm_vcpu *vcpu = apic->vcpu;
bool expired;
WARN_ON(preemptible());
if (!kvm_can_use_hv_timer(vcpu))
return false;
if (!ktimer->tscdeadline) <-------
return false;
...
}
next prev parent reply other threads:[~2021-06-03 15:20 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-03 9:00 [PATCH 1/2] KVM: LAPIC: write 0 to TMICT should also cancel vmx-preemption timer Wanpeng Li
2021-06-03 9:00 ` [PATCH 2/2] KVM: LAPIC: reset TMCCT during vCPU reset Wanpeng Li
2021-06-03 12:27 ` Jim Mattson
2021-06-03 15:34 ` Sean Christopherson
2021-06-08 0:31 ` Wanpeng Li
2021-06-03 15:20 ` Sean Christopherson [this message]
2021-06-04 0:36 ` [PATCH 1/2] KVM: LAPIC: write 0 to TMICT should also cancel vmx-preemption timer Wanpeng Li
2021-06-04 15:37 ` Sean Christopherson
2021-06-08 0:30 ` Wanpeng Li
2021-06-03 23:02 ` David Matlack
2021-06-04 0:32 ` Wanpeng Li
2021-06-04 15:59 ` David Matlack
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