From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: 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: [PATCH] KVM: LAPIC: Accurately guarantee busy wait for timer to expire when using hv_timer
Date: Wed, 28 Apr 2021 19:08:02 +0800 [thread overview]
Message-ID: <1619608082-4187-1-git-send-email-wanpengli@tencent.com> (raw)
From: Wanpeng Li <wanpengli@tencent.com>
Commit ee66e453db13d (KVM: lapic: Busy wait for timer to expire when
using hv_timer) tries to set ktime->expired_tscdeadline by checking
ktime->hv_timer_in_use since lapic timer oneshot/periodic modes which
are emulated by vmx preemption timer also get advanced, they leverage
the same vmx preemption timer logic with tsc-deadline mode. However,
ktime->hv_timer_in_use is cleared before apic_timer_expired() handling,
let's delay this clearing in preemption-disabled region.
Fixes: ee66e453db13d (KVM: lapic: Busy wait for timer to expire when using hv_timer)
Cc: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
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 152591f..c0ebef5 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1913,8 +1913,8 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
if (!apic->lapic_timer.hv_timer_in_use)
goto out;
WARN_ON(rcuwait_active(&vcpu->wait));
- cancel_hv_timer(apic);
apic_timer_expired(apic, false);
+ cancel_hv_timer(apic);
if (apic_lvtt_period(apic) && apic->lapic_timer.period) {
advance_periodic_target_expiration(apic);
--
2.7.4
next reply other threads:[~2021-04-28 11:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-28 11:08 Wanpeng Li [this message]
2021-04-28 22:56 ` [PATCH] KVM: LAPIC: Accurately guarantee busy wait for timer to expire when using hv_timer Sean Christopherson
2021-04-29 15:40 ` Paolo Bonzini
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