2 files changed, 38 insertions, 40 deletions

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index c6f972914f08..a05d0609d918 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -992,16 +992,6 @@ static inline int fix_read_pf(u64 *shadow_ent)
         return 0;
 }
 
-static int may_access(u64 pte, int write, int user)
-{
-
-        if (user && !(pte & PT_USER_MASK))
-                return 0;
-        if (write && !(pte & PT_WRITABLE_MASK))
-                return 0;
-        return 1;
-}
-
 static void paging_free(struct kvm_vcpu *vcpu)
 {
         nonpaging_free(vcpu);
diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index 6bc41950fbb3..afcd2a8f45bb 100644
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -63,13 +63,15 @@ struct guest_walker {
         pt_element_t *ptep;
         pt_element_t inherited_ar;
         gfn_t gfn;
+        u32 error_code;
 };
 
 /*
  * Fetch a guest pte for a guest virtual address
  */
-static void FNAME(walk_addr)(struct guest_walker *walker,
-                             struct kvm_vcpu *vcpu, gva_t addr)
+static int FNAME(walk_addr)(struct guest_walker *walker,
+                            struct kvm_vcpu *vcpu, gva_t addr,
+                            int write_fault, int user_fault)
 {
         hpa_t hpa;
         struct kvm_memory_slot *slot;
@@ -86,7 +88,7 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
                 walker->ptep = &vcpu->pdptrs[(addr >> 30) & 3];
                 root = *walker->ptep;
                 if (!(root & PT_PRESENT_MASK))
-                        return;
+                        goto not_present;
                 --walker->level;
         }
 #endif
@@ -111,11 +113,18 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
                 ASSERT(((unsigned long)walker->table & PAGE_MASK) ==
                        ((unsigned long)ptep & PAGE_MASK));
 
-                if (is_present_pte(*ptep) && !(*ptep &  PT_ACCESSED_MASK))
-                        *ptep |= PT_ACCESSED_MASK;
-
                 if (!is_present_pte(*ptep))
-                        break;
+                        goto not_present;
+
+                if (write_fault && !is_writeble_pte(*ptep))
+                        if (user_fault || is_write_protection(vcpu))
+                                goto access_error;
+
+                if (user_fault && !(*ptep & PT_USER_MASK))
+                        goto access_error;
+
+                if (!(*ptep & PT_ACCESSED_MASK))
+                        *ptep |= PT_ACCESSED_MASK;      /* avoid rmw */
 
                 if (walker->level == PT_PAGE_TABLE_LEVEL) {
                         walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
@@ -146,6 +155,21 @@ static void FNAME(walk_addr)(struct guest_walker *walker,
         }
         walker->ptep = ptep;
         pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)*ptep);
+        return 1;
+
+not_present:
+        walker->error_code = 0;
+        goto err;
+
+access_error:
+        walker->error_code = PFERR_PRESENT_MASK;
+
+err:
+        if (write_fault)
+                walker->error_code |= PFERR_WRITE_MASK;
+        if (user_fault)
+                walker->error_code |= PFERR_USER_MASK;
+        return 0;
 }
 
 static void FNAME(release_walker)(struct guest_walker *walker)
@@ -347,7 +371,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
                                u32 error_code)
 {
         int write_fault = error_code & PFERR_WRITE_MASK;
-        int pte_present = error_code & PFERR_PRESENT_MASK;
         int user_fault = error_code & PFERR_USER_MASK;
         struct guest_walker walker;
         u64 *shadow_pte;
@@ -365,19 +388,19 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
         /*
          * Look up the shadow pte for the faulting address.
          */
-        FNAME(walk_addr)(&walker, vcpu, addr);
-        shadow_pte = FNAME(fetch)(vcpu, addr, &walker);
+        r = FNAME(walk_addr)(&walker, vcpu, addr, write_fault, user_fault);
 
         /*
          * The page is not mapped by the guest.  Let the guest handle it.
          */
-        if (!shadow_pte) {
-                pgprintk("%s: not mapped\n", __FUNCTION__);
-                inject_page_fault(vcpu, addr, error_code);
+        if (!r) {
+                pgprintk("%s: guest page fault\n", __FUNCTION__);
+                inject_page_fault(vcpu, addr, walker.error_code);
                 FNAME(release_walker)(&walker);
                 return 0;
         }
 
+        shadow_pte = FNAME(fetch)(vcpu, addr, &walker);
         pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__,
                  shadow_pte, *shadow_pte);
 
@@ -399,22 +422,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
          * mmio: emulate if accessible, otherwise its a guest fault.
          */
         if (is_io_pte(*shadow_pte)) {
-                if (may_access(*shadow_pte, write_fault, user_fault))
-                        return 1;
-                pgprintk("%s: io work, no access\n", __FUNCTION__);
-                inject_page_fault(vcpu, addr,
-                                  error_code | PFERR_PRESENT_MASK);
-                kvm_mmu_audit(vcpu, "post page fault (io)");
-                return 0;
-        }
-
-        /*
-         * pte not present, guest page fault.
-         */
-        if (pte_present && !fixed && !write_pt) {
-                inject_page_fault(vcpu, addr, error_code);
-                kvm_mmu_audit(vcpu, "post page fault (guest)");
-                return 0;
+                return 1;
         }
 
         ++kvm_stat.pf_fixed;
@@ -429,7 +437,7 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
         pt_element_t guest_pte;
         gpa_t gpa;
 
-        FNAME(walk_addr)(&walker, vcpu, vaddr);
+        FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0);
         guest_pte = *walker.ptep;
         FNAME(release_walker)(&walker);