linux-kernel - [PATCH 2/7] KVM/x86: Replace smp_mb() with smp_store_mb/release() in the walk_shadow_page_lockless

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Date:	Sun, 13 Mar 2016 11:10:25 +0800
From:	Lan Tianyu <tianyu.lan@...el.com>
To:	gleb@...nel.org, pbonzini@...hat.com, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, x86@...nel.org,
	guangrong.xiao@...ux.intel.com
Cc:	Lan Tianyu <tianyu.lan@...el.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/7] KVM/x86: Replace smp_mb() with smp_store_mb/release() in the walk_shadow_page_lockless_begin/end()

Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
---
 arch/x86/kvm/mmu.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5e795af..d1ee68c 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -632,12 +632,12 @@ static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu)
 	 * kvm_flush_remote_tlbs() IPI to all active vcpus.
 	 */
 	local_irq_disable();
-	vcpu->mode = READING_SHADOW_PAGE_TABLES;
+
 	/*
 	 * Make sure a following spte read is not reordered ahead of the write
 	 * to vcpu->mode.
 	 */
-	smp_mb();
+	smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES);
 }
 
 static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
@@ -647,8 +647,7 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
 	 * reads to sptes.  If it does, kvm_commit_zap_page() can see us
 	 * OUTSIDE_GUEST_MODE and proceed to free the shadow page table.
 	 */
-	smp_mb();
-	vcpu->mode = OUTSIDE_GUEST_MODE;
+	smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE);
 	local_irq_enable();
 }
 
-- 
1.8.4.rc0.1.g8f6a3e5.dirty