From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
Since the commit 65855ed8b034 ("KVM: X86: Synchronize the shadow
pagetable before link it"), no sp would be linked with
sp->unsync_children = 1.
So make it WARN if it is the case.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4d188f056933..15d389370f88 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2367,7 +2367,16 @@ static void __link_shadow_page(struct kvm *kvm,
mmu_page_add_parent_pte(cache, sp, sptep);
- if (sp->unsync_children || sp->unsync)
+ /*
+ * The non-direct sub-pagetable must be updated before linking. For
+ * L1 sp, the pagetable is updated via kvm_sync_page() in
+ * kvm_mmu_find_shadow_page() without write-protecting the gfn,
+ * so sp->unsync can be true or false. For higher level non-direct
+ * sp, the pagetable is updated/synced via mmu_sync_children() in
+ * FNAME(fetch)(), so sp->unsync_children can only be false.
+ * WARN_ON_ONCE() if anything happens unexpectedly.
+ */
+ if (WARN_ON_ONCE(sp->unsync_children) || sp->unsync)
mark_unsync(sptep);
}
--
2.19.1.6.gb485710b
