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, 14 insertions, 7 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 1e1c2444cef5..f0fb1a4c522d 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -208,11 +208,8 @@ retry_walk:
                         goto error;
                 }
 
-                if (unlikely(write_fault && !is_writable_pte(pte)
-                             && (user_fault || is_write_protection(vcpu))))
-                        eperm = true;
-
-                if (unlikely(user_fault && !(pte & PT_USER_MASK)))
+                if (!check_write_user_access(vcpu, write_fault, user_fault,
+                                          pte))
                         eperm = true;
 
 #if PTTYPE == 64
@@ -625,8 +622,16 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,
                 return 0;
 
         /* mmio */
-        if (is_error_pfn(pfn))
-                return kvm_handle_bad_page(vcpu->kvm, walker.gfn, pfn);
+        if (is_error_pfn(pfn)) {
+                unsigned access = walker.pte_access;
+                bool dirty = is_dirty_gpte(walker.ptes[walker.level - 1]);
+
+                if (!dirty)
+                        access &= ~ACC_WRITE_MASK;
+
+                return kvm_handle_bad_page(vcpu, mmu_is_nested(vcpu) ? 0 :
+                                           addr, access, walker.gfn, pfn);
+        }
 
         spin_lock(&vcpu->kvm->mmu_lock);
         if (mmu_notifier_retry(vcpu, mmu_seq))
@@ -666,6 +671,8 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
         u64 *sptep;
         int need_flush = 0;
 
+        vcpu_clear_mmio_info(vcpu, gva);
+
         spin_lock(&vcpu->kvm->mmu_lock);
 
         for_each_shadow_entry(vcpu, gva, iterator) {