KVM: MMU: Move sync_page() first pte address calculation out of loop

Move first pte address calculation out of loop to save some cycles.

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index d9dea288e51..5910557b3f3 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -572,12 +572,15 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
 {
         int i, offset, nr_present;
         bool reset_host_protection;
+        gpa_t first_pte_gpa;
 
         offset = nr_present = 0;
 
         if (PTTYPE == 32)
                 offset = sp->role.quadrant << PT64_LEVEL_BITS;
 
+        first_pte_gpa = gfn_to_gpa(sp->gfn) + offset * sizeof(pt_element_t);
+
         for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
                 unsigned pte_access;
                 pt_element_t gpte;
@@ -587,8 +590,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
                 if (!is_shadow_present_pte(sp->spt[i]))
                         continue;
 
-                pte_gpa = gfn_to_gpa(sp->gfn);
-                pte_gpa += (i+offset) * sizeof(pt_element_t);
+                pte_gpa = first_pte_gpa + i * sizeof(pt_element_t);
 
                 if (kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &gpte,
                                           sizeof(pt_element_t)))