linux-kernel - [PATCH 2/2] KVM: MMU: fix relaxing permission

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Message-ID: <4BFC8B8C.7010402@cn.fujitsu.com>
Date:	Wed, 26 May 2010 10:46:36 +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 2/2] KVM: MMU: fix relaxing permission

There is a relaxing permission operation in set_spte():

if guest's CR0.WP is not set and R/W #PF occurs in supervisor-level,
the mapping path might set to writable, then user can allow to write.

Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
 arch/x86/kvm/mmu.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bfd8382..ccbc98b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1859,8 +1859,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	spte |= (u64)pfn << PAGE_SHIFT;
 
-	if ((pte_access & ACC_WRITE_MASK)
-	    || (write_fault && !is_write_protection(vcpu) && !user_fault)) {
+	if (pte_access & ACC_WRITE_MASK) {
 
 		if (level > PT_PAGE_TABLE_LEVEL &&
 		    has_wrprotected_page(vcpu->kvm, gfn, level)) {
-- 
1.6.1.2


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