From 10605204e91f46bdec98bef81923263d245515a0 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 12 Sep 2019 19:46:10 -0700 Subject: [PATCH] KVM: x86/mmu: Revert "KVM: x86/mmu: Remove is_obsolete() call" Now that the fast invalidate mechanism has been reintroduced, restore the performance tweaks for fast invalidation that existed prior to its removal. Paraphrasing the original changelog (commit 5ff0568374ed2 was itself a partial revert): Don't force reloading the remote mmu when zapping an obsolete page, as a MMU_RELOAD request has already been issued by kvm_mmu_zap_all_fast() immediately after incrementing mmu_valid_gen, i.e. after marking pages obsolete. This reverts commit 5ff0568374ed2e585376a3832857ade5daccd381. Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu.c | 29 +++++++++++++++++++++++------ arch/x86/kvm/x86.c | 1 + 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 652f2ce14583..e552fd5cd33d 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2752,7 +2752,12 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, } else { list_move(&sp->link, &kvm->arch.active_mmu_pages); - if (!sp->role.invalid) + /* + * Obsolete pages cannot be used on any vCPUs, see the comment + * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also + * treats invalid shadow pages as being obsolete. + */ + if (!is_obsolete_sp(kvm, sp)) kvm_reload_remote_mmus(kvm); } @@ -5675,7 +5680,6 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) static void kvm_zap_obsolete_pages(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; - LIST_HEAD(invalid_list); int nr_zapped, batch = 0; restart: @@ -5708,8 +5712,8 @@ restart: goto restart; } - if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, - &nr_zapped)) { + if (__kvm_mmu_prepare_zap_page(kvm, sp, + &kvm->arch.zapped_obsolete_pages, &nr_zapped)) { batch += nr_zapped; goto restart; } @@ -5720,7 +5724,7 @@ restart: * KVM is not in the middle of a lockless shadow page table walk, which * may reference the pages. */ - kvm_mmu_commit_zap_page(kvm, &invalid_list); + kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); } /* @@ -5752,6 +5756,11 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) spin_unlock(&kvm->mmu_lock); } +static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) +{ + return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); +} + static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, struct kvm_memory_slot *slot, struct kvm_page_track_notifier_node *node) @@ -6022,16 +6031,24 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) * want to shrink a VM that only started to populate its MMU * anyway. */ - if (!kvm->arch.n_used_mmu_pages) + if (!kvm->arch.n_used_mmu_pages && + !kvm_has_zapped_obsolete_pages(kvm)) continue; idx = srcu_read_lock(&kvm->srcu); spin_lock(&kvm->mmu_lock); + if (kvm_has_zapped_obsolete_pages(kvm)) { + kvm_mmu_commit_zap_page(kvm, + &kvm->arch.zapped_obsolete_pages); + goto unlock; + } + if (prepare_zap_oldest_mmu_page(kvm, &invalid_list)) freed++; kvm_mmu_commit_zap_page(kvm, &invalid_list); +unlock: spin_unlock(&kvm->mmu_lock); srcu_read_unlock(&kvm->srcu, idx); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 977b36348bed..c9a3d8efe1c2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9425,6 +9425,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) INIT_HLIST_HEAD(&kvm->arch.mask_notifier_list); INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); + INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages); INIT_LIST_HEAD(&kvm->arch.assigned_dev_head); atomic_set(&kvm->arch.noncoherent_dma_count, 0);