linux-kernel - [PATCH 1/10] KVM: MMU: fix kvm_mmu_slot_remove_write

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Date:	Fri, 04 Mar 2011 18:56:41 +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 <kvm@...r.kernel.org>
Subject: [PATCH 1/10] KVM: MMU: fix kvm_mmu_slot_remove_write_access

Only remove write access in the last sptes

Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
 arch/x86/kvm/mmu.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b6a9963..b9bf016 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3540,12 +3540,17 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
 
 		pt = sp->spt;
 		for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
-			if (sp->role.level != PT_PAGE_TABLE_LEVEL
-			    && is_large_pte(pt[i])) {
+			if (!is_shadow_present_pte(pt[i]) ||
+			      !is_last_spte(pt[i], sp->role.level))
+				continue;
+
+			if (is_large_pte(pt[i])) {
 				drop_spte(kvm, &pt[i],
 					  shadow_trap_nonpresent_pte);
 				--kvm->stat.lpages;
+				continue;
 			}
+
 			/* avoid RMW */
 			if (is_writable_pte(pt[i]))
 				update_spte(&pt[i], pt[i] & ~PT_WRITABLE_MASK);
-- 
1.7.4
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