From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Date: Fri, 4 Mar 2011 10:56:41 +0000 (+0800)
Subject: KVM: MMU: fix kvm_mmu_slot_remove_write_access dropping intermediate W bits
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=da8dc75f0c4663a568a0ed4e744c6d55d428d8b6;p=linux-beck.git

KVM: MMU: fix kvm_mmu_slot_remove_write_access dropping intermediate W bits

Only remove write access in the last sptes.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b6a9963400a7..b9bf016d7f0f 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);