KVM: Add kvm_read_guest_atomic()
In preparation for a mmu spinlock, add kvm_read_guest_atomic()
and use it in fetch() and prefetch_page().
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 7f83f55..136a65d 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -316,10 +316,12 @@
metaphysical, access,
shadow_ent, &new_page);
if (new_page && !metaphysical) {
+ int r;
pt_element_t curr_pte;
- kvm_read_guest(vcpu->kvm, walker->pte_gpa[level - 2],
- &curr_pte, sizeof(curr_pte));
- if (curr_pte != walker->ptes[level - 2])
+ r = kvm_read_guest_atomic(vcpu->kvm,
+ walker->pte_gpa[level - 2],
+ &curr_pte, sizeof(curr_pte));
+ if (r || curr_pte != walker->ptes[level - 2])
return NULL;
}
shadow_addr = __pa(shadow_page->spt);
@@ -429,9 +431,8 @@
static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
- int i, offset = 0;
- pt_element_t *gpt;
- struct page *page;
+ int i, offset = 0, r = 0;
+ pt_element_t pt;
if (sp->role.metaphysical
|| (PTTYPE == 32 && sp->role.level > PT_PAGE_TABLE_LEVEL)) {
@@ -441,15 +442,18 @@
if (PTTYPE == 32)
offset = sp->role.quadrant << PT64_LEVEL_BITS;
- page = gfn_to_page(vcpu->kvm, sp->gfn);
- gpt = kmap_atomic(page, KM_USER0);
- for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
- if (is_present_pte(gpt[offset + i]))
+
+ 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;
- kunmap_atomic(gpt, KM_USER0);
- kvm_release_page_clean(page);
+ }
}
#undef pt_element_t