KVM: MMU: introduce is_last_spte helper

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>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b6e4cda..f85d995 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/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;
@@ -1313,25 +1322,17 @@ static void kvm_mmu_page_unlink_children(struct kvm *kvm,
 
        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]);
                        }
                }
@@ -2381,8 +2382,7 @@ static void mmu_pte_write_zap_pte(struct kvm_vcpu *vcpu,
 
        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);