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KVM: MMU: Optimize prefetch_page() 

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

Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity 2008-05-29 14:20:16 +03:00
parent 38d5bc6d50
commit eab9f71feb
1 changed files with 15 additions and 13 deletions
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28
arch/x86/kvm/paging_tmpl.h
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@ -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;
else
sp->spt[i] = shadow_notrap_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+j] = shadow_notrap_nonpresent_pte;
}
}