linux-kernel - [PATCH 3/7] KVM: MMU: avoid double write protected in sync page path

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Message-ID: <4C123A7C.1070205@cn.fujitsu.com>
Date:	Fri, 11 Jun 2010 21:30:36 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	KVM list <kvm@...r.kernel.org>
Subject: [PATCH 3/7] KVM: MMU: avoid double write protected in sync page path

The sync page is already write protected in mmu_sync_children(), don't
write protected it again

Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
 arch/x86/kvm/mmu.c |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 21ab85b..2ffd673 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1216,6 +1216,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
 		if ((sp)->gfn != (gfn) || (sp)->role.direct ||		\
 			(sp)->role.invalid) {} else
 
+/* @sp->gfn should be write-protected at the call site */
 static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 			   struct list_head *invalid_list, bool clear_unsync)
 {
@@ -1224,11 +1225,8 @@ static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
 		return 1;
 	}
 
-	if (clear_unsync) {
-		if (rmap_write_protect(vcpu->kvm, sp->gfn))
-			kvm_flush_remote_tlbs(vcpu->kvm);
+	if (clear_unsync)
 		kvm_unlink_unsync_page(vcpu->kvm, sp);
-	}
 
 	if (vcpu->arch.mmu.sync_page(vcpu, sp)) {
 		kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
-- 
1.6.1.2


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