KVM: MMU: fix walking shadow page table

Properly check the last mapping, and do not walk to the next level if last spte
is met

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 da0f3b0..03323dc 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1517,10 +1517,6 @@ static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator)
        if (iterator->level < PT_PAGE_TABLE_LEVEL)
                return false;
 
-       if (iterator->level == PT_PAGE_TABLE_LEVEL)
-               if (is_large_pte(*iterator->sptep))
-                       return false;
-
        iterator->index = SHADOW_PT_INDEX(iterator->addr, iterator->level);
        iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index;
        return true;
@@ -1528,6 +1524,11 @@ static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator)
 
 static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
 {
+       if (is_last_spte(*iterator->sptep, iterator->level)) {
+               iterator->level = 0;
+               return;
+       }
+
        iterator->shadow_addr = *iterator->sptep & PT64_BASE_ADDR_MASK;
        --iterator->level;
 }