KVM: MMU: cache mmio info on page fault path

If the page fault is caused by mmio, we can cache the mmio info, later, we do
not need to walk guest page table and quickly know it is a mmio fault while we
emulate the mmio instruction

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a1dbd0443545..028a0f25e8a0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4016,6 +4016,14 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
 {
         u32 access = (kvm_x86_ops->get_cpl(vcpu) == 3) ? PFERR_USER_MASK : 0;
 
+        if (vcpu_match_mmio_gva(vcpu, gva) &&
+                  check_write_user_access(vcpu, write, access,
+                  vcpu->arch.access)) {
+                *gpa = vcpu->arch.mmio_gfn << PAGE_SHIFT |
+                                        (gva & (PAGE_SIZE - 1));
+                return 1;
+        }
+
         if (write)
                 access |= PFERR_WRITE_MASK;
 
@@ -4028,6 +4036,9 @@ static int vcpu_mmio_gva_to_gpa(struct kvm_vcpu *vcpu, unsigned long gva,
         if ((*gpa & PAGE_MASK) == APIC_DEFAULT_PHYS_BASE)
                 return 1;
 
+        if (vcpu_match_mmio_gpa(vcpu, *gpa))
+                return 1;
+
         return 0;
 }