From: Wanpeng Li Date: Wed, 28 Apr 2021 11:08:02 +0000 (+0800) Subject: KVM: LAPIC: Accurately guarantee busy wait for timer to expire when using hv_timer X-Git-Tag: v5.11.22~79 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d59b53f583fd788c89661ec84cb294735b831ccd;p=thirdparty%2Fkernel%2Fstable.git KVM: LAPIC: Accurately guarantee busy wait for timer to expire when using hv_timer [ Upstream commit d981dd15498b188636ec5a7d8ad485e650f63d8d ] 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") Reviewed-by: Sean Christopherson Signed-off-by: Wanpeng Li Message-Id: <1619608082-4187-1-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 570fa298083cd..70eb00f4317fe 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -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);