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 b6a9963..b9bf016 100644 (file)
--- 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);