[patch 1/6] KVM: MMU: introduce is_last_spte helper

Marcelo Tosatti
2009-06-10T15:31:26Z

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Hiding some of the last largepage / level interaction (which is useful
for gbpages and for zero based levels).

Also merge the PT_PAGE_TABLE_LEVEL clearing loop in unlink_children.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm/arch/x86/kvm/mmu.c
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.c
+++ kvm/arch/x86/kvm/mmu.c
@@ -250,6 +250,15 @@ static int is_rmap_spte(u64 pte)
return is_shadow_present_pte(pte);
}

+static int is_last_spte(u64 pte, int level)
+{
+ if (level == PT_PAGE_TABLE_LEVEL)
+ return 1;
+ if (level == PT_DIRECTORY_LEVEL && is_large_pte(pte))
+ return 1;
+ return 0;
+}
+
static pfn_t spte_to_pfn(u64 pte)
{
return (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
@@ -1293,25 +1302,17 @@ static void kvm_mmu_page_unlink_children

pt = sp->spt;

- if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
- for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
- if (is_shadow_present_pte(pt[i]))
- rmap_remove(kvm, &pt[i]);
- pt[i] = shadow_trap_nonpresent_pte;
- }
- return;
- }
-
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
ent = pt[i];

if (is_shadow_present_pte(ent)) {
- if (!is_large_pte(ent)) {
+ if (!is_last_spte(ent, sp->role.level)) {
ent &= PT64_BASE_ADDR_MASK;
mmu_page_remove_parent_pte(page_header(ent),
&pt[i]);
} else {
- --kvm->stat.lpages;
+ if (is_large_pte(ent))
+ --kvm->stat.lpages;
rmap_remove(kvm, &pt[i]);
}
}
@@ -2357,8 +2358,7 @@ static void mmu_pte_write_zap_pte(struct

pte = *spte;
if (is_shadow_present_pte(pte)) {
- if (sp->role.level == PT_PAGE_TABLE_LEVEL ||
- is_large_pte(pte))
+ if (is_last_spte(pte, sp->role.level))
rmap_remove(vcpu->kvm, spte);
else {
child = page_header(pte & PT64_BASE_ADDR_MASK);

--