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>

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 36a80ed..f887e4c 100644 (file)
--- 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);
        }
 }