KVM: MMU: fix kvm_mmu_zap_page() and its calling path

This patch fix:

- calculate zapped page number properly in mmu_zap_unsync_children()
- calculate freeed page number properly kvm_mmu_change_mmu_pages()
- if zapped children page it shoud restart hlist walking

KVM-Stable-Tag.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 48aeee8eefb0..19a8906bcaa2 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1490,8 +1490,8 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
                 for_each_sp(pages, sp, parents, i) {
                         kvm_mmu_zap_page(kvm, sp);
                         mmu_pages_clear_parents(&parents);
+                        zapped++;
                 }
-                zapped += pages.nr;
                 kvm_mmu_pages_init(parent, &parents, &pages);
         }
 
@@ -1542,14 +1542,16 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages)
          */
 
         if (used_pages > kvm_nr_mmu_pages) {
-                while (used_pages > kvm_nr_mmu_pages) {
+                while (used_pages > kvm_nr_mmu_pages &&
+                        !list_empty(&kvm->arch.active_mmu_pages)) {
                         struct kvm_mmu_page *page;
 
                         page = container_of(kvm->arch.active_mmu_pages.prev,
                                             struct kvm_mmu_page, link);
-                        kvm_mmu_zap_page(kvm, page);
+                        used_pages -= kvm_mmu_zap_page(kvm, page);
                         used_pages--;
                 }
+                kvm_nr_mmu_pages = used_pages;
                 kvm->arch.n_free_mmu_pages = 0;
         }
         else
@@ -1596,7 +1598,8 @@ static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
                     && !sp->role.invalid) {
                         pgprintk("%s: zap %lx %x\n",
                                  __func__, gfn, sp->role.word);
-                        kvm_mmu_zap_page(kvm, sp);
+                        if (kvm_mmu_zap_page(kvm, sp))
+                                nn = bucket->first;
                 }
         }
 }