KVM: MMU: split kvm_mmu_free_page

Split kvm_mmu_free_page to kvm_mmu_isolate_page and
kvm_mmu_free_page

One is used to remove the page from cache under mmu lock and the other is
used to free page table out of mmu lock

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 91d30695677b..2f8543c65fa3 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1039,14 +1039,28 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr)
         percpu_counter_add(&kvm_total_used_mmu_pages, nr);
 }
 
-static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
+/*
+ * Remove the sp from shadow page cache, after call it,
+ * we can not find this sp from the cache, and the shadow
+ * page table is still valid.
+ * It should be under the protection of mmu lock.
+ */
+static void kvm_mmu_isolate_page(struct kvm_mmu_page *sp)
 {
         ASSERT(is_empty_shadow_page(sp->spt));
         hlist_del(&sp->hash_link);
-        list_del(&sp->link);
-        free_page((unsigned long)sp->spt);
         if (!sp->role.direct)
                 free_page((unsigned long)sp->gfns);
+}
+
+/*
+ * Free the shadow page table and the sp, we can do it
+ * out of the protection of mmu lock.
+ */
+static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
+{
+        list_del(&sp->link);
+        free_page((unsigned long)sp->spt);
         kmem_cache_free(mmu_page_header_cache, sp);
 }
 
@@ -1678,6 +1692,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
         do {
                 sp = list_first_entry(invalid_list, struct kvm_mmu_page, link);
                 WARN_ON(!sp->role.invalid || sp->root_count);
+                kvm_mmu_isolate_page(sp);
                 kvm_mmu_free_page(sp);
         } while (!list_empty(invalid_list));