linux-kernel - [PATCH] KVM: apic: reuse smp_wmb() in kvm_make

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Date:   Thu, 6 Feb 2020 09:59:35 +0800
From:   linmiaohe <linmiaohe@...wei.com>
To:     <pbonzini@...hat.com>, <rkrcmar@...hat.com>,
        <sean.j.christopherson@...el.com>, <vkuznets@...hat.com>,
        <wanpengli@...cent.com>, <jmattson@...gle.com>, <joro@...tes.org>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
        <hpa@...or.com>
CC:     <linmiaohe@...wei.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <x86@...nel.org>
Subject: [PATCH] KVM: apic: reuse smp_wmb() in kvm_make_request()

From: Miaohe Lin <linmiaohe@...wei.com>

There is already an smp_mb() barrier in kvm_make_request(). We reuse it
here.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 arch/x86/kvm/lapic.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index eafc631d305c..ea871206a370 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1080,9 +1080,12 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
 			result = 1;
 			/* assumes that there are only KVM_APIC_INIT/SIPI */
 			apic->pending_events = (1UL << KVM_APIC_INIT);
-			/* make sure pending_events is visible before sending
-			 * the request */
-			smp_wmb();
+			/*
+			 * Make sure pending_events is visible before sending
+			 * the request.
+			 * There is already an smp_wmb() in kvm_make_request(),
+			 * we reuse that barrier here.
+			 */
 			kvm_make_request(KVM_REQ_EVENT, vcpu);
 			kvm_vcpu_kick(vcpu);
 		}
-- 
2.19.1