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KVM: LAPIC: Accurately guarantee busy wait for timer to expire when using hv_timer

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[ Upstream commit d981dd15498b188636ec5a7d8ad485e650f63d8d ]

Commit ee66e453db (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: ee66e453db ("KVM: lapic: Busy wait for timer to expire when using hv_timer")
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Message-Id: <1619608082-4187-1-git-send-email-wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Wanpeng Li 2021-04-28 19:08:02 +08:00 committed by Greg Kroah-Hartman
parent ce76392523
commit 2e0ce36d0b
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kvm/lapic.c
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@ -1908,8 +1908,8 @@ 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);