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>

1 files changed, 29 insertions, 24 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 41e801b53064..ab12be4eb105 100644
--- 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);
         }