KVM: MMU: Optimize page unshadowing

Using kvm_mmu_lookup_page() will result in multiple scans of the hash chains;
use hlist_for_each_entry_safe() to achieve a single scan instead.

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

1 files changed, 12 insertions, 3 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 15850809b55b..aac0499947d8 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1471,11 +1471,20 @@ static int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
 
 static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
 {
+        unsigned index;
+        struct hlist_head *bucket;
         struct kvm_mmu_page *sp;
+        struct hlist_node *node, *nn;
 
-        while ((sp = kvm_mmu_lookup_page(kvm, gfn)) != NULL) {
-                pgprintk("%s: zap %lx %x\n", __func__, gfn, sp->role.word);
-                kvm_mmu_zap_page(kvm, sp);
+        index = kvm_page_table_hashfn(gfn);
+        bucket = &kvm->arch.mmu_page_hash[index];
+        hlist_for_each_entry_safe(sp, node, nn, bucket, hash_link) {
+                if (sp->gfn == gfn && !sp->role.metaphysical
+                    && !sp->role.invalid) {
+                        pgprintk("%s: zap %lx %x\n",
+                                 __func__, gfn, sp->role.word);
+                        kvm_mmu_zap_page(kvm, sp);
+                }
         }
 }