From: Wanpeng Li <kernellwp@gmail.com>
To: David Matlack <dmatlack@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
kvm list <kvm@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.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: Fri, 4 Jun 2021 08:32:57 +0800 [thread overview]
Message-ID: <CANRm+CzNeGzJyisK659h1kdgcQQ+Y7OwW+tiXPnZ9gmiGB1qUA@mail.gmail.com> (raw)
In-Reply-To: <CALzav=e9pbkk0=Yz9s1b+53MEy7yuo_otoFM75fNeoJGCQjqCg@mail.gmail.com>
On Fri, 4 Jun 2021 at 07:02, David Matlack <dmatlack@google.com> wrote:
>
> On Thu, Jun 3, 2021 at 2:04 AM Wanpeng Li <kernellwp@gmail.com> 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.
>
> If KVM is not correctly emulating this behavior then could you also
> add a kvm-unit-test to test for the correct behavior?
A simple test here, the test will hang after the patch since it will
not receive the spurious interrupt any more.
diff --git a/x86/apic.c b/x86/apic.c
index a7681fe..947d018 100644
--- a/x86/apic.c
+++ b/x86/apic.c
@@ -488,6 +488,14 @@ static void test_apic_timer_one_shot(void)
*/
report((lvtt_counter == 1) && (tsc2 - tsc1 >= interval),
"APIC LVT timer one shot");
+
+ lvtt_counter = 0;
+ apic_write(APIC_TMICT, interval);
+ apic_write(APIC_TMICT, 0);
+ while (!lvtt_counter);
+
+ report((lvtt_counter == 1),
+ "APIC LVT timer one shot spurious interrupt");
}
next prev parent reply other threads:[~2021-06-04 0:34 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 ` [PATCH 1/2] KVM: LAPIC: write 0 to TMICT should also cancel vmx-preemption timer Sean Christopherson
2021-06-04 0:36 ` 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 [this message]
2021-06-04 15:59 ` David Matlack
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