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@xxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 55 ++++++++++++++++++++++++++++-----------------------
1 files changed, 30 insertions(+), 25 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index c4b980a..eb20682 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);
}
--
1.6.1.2
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