linux-kernel - [PATCH v2] KVM: apic: reuse smp_wmb() in kvm_make

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Date:   Fri, 7 Feb 2020 23:22:07 +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 v2] KVM: apic: reuse smp_wmb() in kvm_make_request()

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

kvm_make_request() provides smp_wmb() so pending_events changes are
guaranteed to be visible.

Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
v1->v2:
Collected Vitaly's R-b
Use Vitaly's alternative wording
Drop unnecessary comment as suggested by Sean Christopherson
---
 arch/x86/kvm/lapic.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index eafc631d305c..afcd30d44cbb 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1080,9 +1080,6 @@ 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();
 			kvm_make_request(KVM_REQ_EVENT, vcpu);
 			kvm_vcpu_kick(vcpu);
 		}
-- 
2.19.1