KVM: MMU: clear unsync_child_bitmap completely

In current code, some page's unsync_child_bitmap is not cleared completely
in mmu_sync_children(), for example, if two PDPEs shard one PDT, one of
PDPE's unsync_child_bitmap is not cleared.

Currently, it not harm anything just little overload, but it's the prepare
work for the later patch

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 41e801b..ab12be4 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1149,33 +1149,38 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
        int i, ret, nr_unsync_leaf = 0;
 
        for_each_unsync_children(sp->unsync_child_bitmap, i) {
+               struct kvm_mmu_page *child;
                u64 ent = sp->spt[i];
 
-               if (is_shadow_present_pte(ent) && !is_large_pte(ent)) {
-                       struct kvm_mmu_page *child;
-                       child = page_header(ent & PT64_BASE_ADDR_MASK);
-
-                       if (child->unsync_children) {
-                               if (mmu_pages_add(pvec, child, i))
-                                       return -ENOSPC;
-
-                               ret = __mmu_unsync_walk(child, pvec);
-                               if (!ret) {
-                                       __clear_bit(i, sp->unsync_child_bitmap);
-                                       sp->unsync_children--;
-                                       WARN_ON((int)sp->unsync_children < 0);
-                               } else if (ret > 0)
-                                       nr_unsync_leaf += ret;
-                               else
-                                       return ret;
-                       }
+               if (!is_shadow_present_pte(ent) || is_large_pte(ent))
+                       goto clear_child_bitmap;
+
+               child = page_header(ent & PT64_BASE_ADDR_MASK);
+
+               if (child->unsync_children) {
+                       if (mmu_pages_add(pvec, child, i))
+                               return -ENOSPC;
+
+                       ret = __mmu_unsync_walk(child, pvec);
+                       if (!ret)
+                               goto clear_child_bitmap;
+                       else if (ret > 0)
+                               nr_unsync_leaf += ret;
+                       else
+                               return ret;
+               } else if (child->unsync) {
+                       nr_unsync_leaf++;
+                       if (mmu_pages_add(pvec, child, i))
+                               return -ENOSPC;
+               } else
+                        goto clear_child_bitmap;
 
-                       if (child->unsync) {
-                               nr_unsync_leaf++;
-                               if (mmu_pages_add(pvec, child, i))
-                                       return -ENOSPC;
-                       }
-               }
+               continue;
+
+clear_child_bitmap:
+               __clear_bit(i, sp->unsync_child_bitmap);
+               sp->unsync_children--;
+               WARN_ON((int)sp->unsync_children < 0);
        }