[PATCH] KVM: MMU: If emulating an instruction fails, try unprotecting the page

A page table may have been recycled into a regular page, and so any
instruction can be executed on it.  Unprotect the page and let the cpu do its
thing.

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, 2 insertions, 0 deletions

diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 047f6f6ed3f6..79032438dd16 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1063,6 +1063,8 @@ int emulate_instruction(struct kvm_vcpu *vcpu,
         }
 
         if (r) {
+                if (kvm_mmu_unprotect_page_virt(vcpu, cr2))
+                        return EMULATE_DONE;
                 if (!vcpu->mmio_needed) {
                         report_emulation_failure(&emulate_ctxt);
                         return EMULATE_FAIL;