KVM: MMU: introduce FNAME(prefetch_gpte)

The only difference between FNAME(update_pte) and FNAME(pte_prefetch)
is that the former is allowed to prefetch gfn from dirty logged slot,
so introduce a common function to prefetch spte

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 24 insertions, 31 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 36a80edf8006..f887e4cfc1fe 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -305,31 +305,43 @@ static int FNAME(walk_addr_nested)(struct guest_walker *walker,
                                         addr, access);
 }
 
-static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
-                              u64 *spte, const void *pte)
+static bool
+FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+                     u64 *spte, pt_element_t gpte, bool no_dirty_log)
 {
-        pt_element_t gpte;
         unsigned pte_access;
+        gfn_t gfn;
         pfn_t pfn;
 
-        gpte = *(const pt_element_t *)pte;
         if (prefetch_invalid_gpte(vcpu, sp, spte, gpte))
-                return;
+                return false;
 
         pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);
+
+        gfn = gpte_to_gfn(gpte);
         pte_access = sp->role.access & gpte_access(vcpu, gpte);
         protect_clean_gpte(&pte_access, gpte);
-        pfn = gfn_to_pfn_atomic(vcpu->kvm, gpte_to_gfn(gpte));
+        pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
+                        no_dirty_log && (pte_access & ACC_WRITE_MASK));
         if (is_invalid_pfn(pfn))
-                return;
+                return false;
 
         /*
-         * we call mmu_set_spte() with host_writable = true because that
-         * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
+         * we call mmu_set_spte() with host_writable = true because
+         * pte_prefetch_gfn_to_pfn always gets a writable pfn.
          */
         mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
-                     NULL, PT_PAGE_TABLE_LEVEL,
-                     gpte_to_gfn(gpte), pfn, true, true);
+                     NULL, PT_PAGE_TABLE_LEVEL, gfn, pfn, true, true);
+
+        return true;
+}
+
+static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+                              u64 *spte, const void *pte)
+{
+        pt_element_t gpte = *(const pt_element_t *)pte;
+
+        FNAME(prefetch_gpte)(vcpu, sp, spte, gpte, false);
 }
 
 static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,
@@ -375,33 +387,14 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
         spte = sp->spt + i;
 
         for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) {
-                pt_element_t gpte;
-                unsigned pte_access;
-                gfn_t gfn;
-                pfn_t pfn;
-
                 if (spte == sptep)
                         continue;
 
                 if (is_shadow_present_pte(*spte))
                         continue;
 
-                gpte = gptep[i];
-
-                if (prefetch_invalid_gpte(vcpu, sp, spte, gpte))
-                        continue;
-
-                pte_access = sp->role.access & gpte_access(vcpu, gpte);
-                protect_clean_gpte(&pte_access, gpte);
-                gfn = gpte_to_gfn(gpte);
-                pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
-                                      pte_access & ACC_WRITE_MASK);
-                if (is_invalid_pfn(pfn))
+                if (!FNAME(prefetch_gpte)(vcpu, sp, spte, gptep[i], true))
                         break;
-
-                mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
-                             NULL, PT_PAGE_TABLE_LEVEL, gfn,
-                             pfn, true, true);
         }
 }