KVM: MMU: count used shadow pages on prepareing path

Move counting used shadow pages from commiting path to preparing path to
reduce tlb flush on some paths

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

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a62ba462972eff9ffdcdcbd2cb14e6e3461e0089..91d30695677b2b9e9e84a5c4fc9b7452335a0d32 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1039,7 +1039,7 @@ 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 *kvm, struct kvm_mmu_page *sp)
+static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
 {
        ASSERT(is_empty_shadow_page(sp->spt));
        hlist_del(&sp->hash_link);
@@ -1048,7 +1048,6 @@ static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
        if (!sp->role.direct)
                free_page((unsigned long)sp->gfns);
        kmem_cache_free(mmu_page_header_cache, sp);
-       kvm_mod_used_mmu_pages(kvm, -1);
 }
 
 static unsigned kvm_page_table_hashfn(gfn_t gfn)
@@ -1655,6 +1654,7 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
                /* Count self */
                ret++;
                list_move(&sp->link, invalid_list);
+               kvm_mod_used_mmu_pages(kvm, -1);
        } else {
                list_move(&sp->link, &kvm->arch.active_mmu_pages);
                kvm_reload_remote_mmus(kvm);
@@ -1678,7 +1678,7 @@ 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_free_page(kvm, sp);
+               kvm_mmu_free_page(sp);
        } while (!list_empty(invalid_list));
 
 }
@@ -1704,8 +1704,8 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int goal_nr_mmu_pages)
                        page = container_of(kvm->arch.active_mmu_pages.prev,
                                            struct kvm_mmu_page, link);
                        kvm_mmu_prepare_zap_page(kvm, page, &invalid_list);
-                       kvm_mmu_commit_zap_page(kvm, &invalid_list);
                }
+               kvm_mmu_commit_zap_page(kvm, &invalid_list);
                goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages;
        }
 
@@ -3302,9 +3302,9 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
                sp = container_of(vcpu->kvm->arch.active_mmu_pages.prev,
                                  struct kvm_mmu_page, link);
                kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list);
-               kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
                ++vcpu->kvm->stat.mmu_recycled;
        }
+       kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
 }
 
 int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code,