Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fix from Paolo Bonzini:
 "This single patch fixes a regression caused by one of the
  optimizations introduced in 3.11, which is generally visible only on
  AMD processors"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: MMU: avoid fast page fault fixing mmio page fault

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 0d094da49541..9e9285ae9b94 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2811,6 +2811,13 @@ exit:
 static bool page_fault_can_be_fast(struct kvm_vcpu *vcpu, u32 error_code)
 {
         /*
+         * Do not fix the mmio spte with invalid generation number which
+         * need to be updated by slow page fault path.
+         */
+        if (unlikely(error_code & PFERR_RSVD_MASK))
+                return false;
+
+        /*
          * #PF can be fast only if the shadow page table is present and it
          * is caused by write-protect, that means we just need change the
          * W bit of the spte which can be done out of mmu-lock.