[PATCH] KVM: MMU: Never free a shadow page actively serving as a root

We always need cr3 to point to something valid, so if we detect that we're
freeing a root page, simply push it back to the top of the active list.

Signed-off-by: Avi Kivity <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 201b2735ca9..b24a86e1f43 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -134,6 +134,7 @@ struct kvm_mmu_page {
                                     */
         int global;              /* Set if all ptes in this page are global */
         int multimapped;         /* More than one parent_pte? */
+        int root_count;          /* Currently serving as active root */
         union {
                 u64 *parent_pte;               /* !multimapped */
                 struct hlist_head parent_ptes; /* multimapped, kvm_pte_chain */