Commit eab9f71f authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: MMU: Optimize prefetch_page() 



Instead of reading each pte individually, read 256 bytes worth of ptes and
batch process them.

Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 38d5bc6d

arch/x86/kvm/paging_tmpl.h

+15 −13
Original line number Diff line number Diff line
@@ -460,8 +460,9 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr) 
static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,

				 struct kvm_mmu_page *sp)

{

	int i, offset = 0, r = 0;

	pt_element_t pt;

	int i, j, offset, r;

	pt_element_t pt[256 / sizeof(pt_element_t)];

	gpa_t pte_gpa;



	if (sp->role.metaphysical

	    || (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
@@ -469,19 +470,20 @@ static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu, 
		return;

	}



	if (PTTYPE == 32)

	pte_gpa = gfn_to_gpa(sp->gfn);

	if (PTTYPE == 32) {

		offset = sp->role.quadrant << PT64_LEVEL_BITS;

		pte_gpa += offset * sizeof(pt_element_t);

	}



	for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {

		gpa_t pte_gpa = gfn_to_gpa(sp->gfn);

		pte_gpa += (i+offset) * sizeof(pt_element_t);



		r = kvm_read_guest_atomic(vcpu->kvm, pte_gpa, &pt,

					  sizeof(pt_element_t));

		if (r || is_present_pte(pt))

			sp->spt[i] = shadow_trap_nonpresent_pte;

	for (i = 0; i < PT64_ENT_PER_PAGE; i += ARRAY_SIZE(pt)) {

		r = kvm_read_guest_atomic(vcpu->kvm, pte_gpa, pt, sizeof pt);

		pte_gpa += ARRAY_SIZE(pt) * sizeof(pt_element_t);

		for (j = 0; j < ARRAY_SIZE(pt); ++j)

			if (r || is_present_pte(pt[j]))

				sp->spt[i+j] = shadow_trap_nonpresent_pte;

			else

			sp->spt[i] = shadow_notrap_nonpresent_pte;

				sp->spt[i+j] = shadow_notrap_nonpresent_pte;

	}

}