diff options
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 4 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu.c | 73 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 3 |
3 files changed, 31 insertions, 49 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 69e39bc..64c8989 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -240,8 +240,6 @@ struct kvm_mmu_page { #endif int write_flooding_count; - - struct rcu_head rcu; }; struct kvm_pio_request { @@ -540,8 +538,6 @@ struct kvm_arch { u64 hv_guest_os_id; u64 hv_hypercall; - atomic_t reader_counter; - #ifdef CONFIG_KVM_MMU_AUDIT int audit_point; #endif diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 07424cf..72102e0 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -551,19 +551,29 @@ static u64 mmu_spte_get_lockless(u64 *sptep) static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) { - rcu_read_lock(); - atomic_inc(&vcpu->kvm->arch.reader_counter); - - /* Increase the counter before walking shadow page table */ - smp_mb__after_atomic_inc(); + /* + * Prevent page table teardown by making any free-er wait during + * kvm_flush_remote_tlbs() IPI to all active vcpus. + */ + local_irq_disable(); + vcpu->mode = READING_SHADOW_PAGE_TABLES; + /* + * Make sure a following spte read is not reordered ahead of the write + * to vcpu->mode. + */ + smp_mb(); } static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) { - /* Decrease the counter after walking shadow page table finished */ - smp_mb__before_atomic_dec(); - atomic_dec(&vcpu->kvm->arch.reader_counter); - rcu_read_unlock(); + /* + * Make sure the write to vcpu->mode is not reordered in front of + * reads to sptes. If it does, kvm_commit_zap_page() can see us + * OUTSIDE_GUEST_MODE and proceed to free the shadow page table. + */ + smp_mb(); + vcpu->mode = OUTSIDE_GUEST_MODE; + local_irq_enable(); } static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache, @@ -1989,30 +1999,6 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, return ret; } -static void kvm_mmu_isolate_pages(struct list_head *invalid_list) -{ - struct kvm_mmu_page *sp; - - list_for_each_entry(sp, invalid_list, link) - kvm_mmu_isolate_page(sp); -} - -static void free_pages_rcu(struct rcu_head *head) -{ - struct kvm_mmu_page *next, *sp; - - sp = container_of(head, struct kvm_mmu_page, rcu); - while (sp) { - if (!list_empty(&sp->link)) - next = list_first_entry(&sp->link, - struct kvm_mmu_page, link); - else - next = NULL; - kvm_mmu_free_page(sp); - sp = next; - } -} - static void kvm_mmu_commit_zap_page(struct kvm *kvm, struct list_head *invalid_list) { @@ -2021,17 +2007,17 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, if (list_empty(invalid_list)) return; - kvm_flush_remote_tlbs(kvm); - - if (atomic_read(&kvm->arch.reader_counter)) { - kvm_mmu_isolate_pages(invalid_list); - sp = list_first_entry(invalid_list, struct kvm_mmu_page, link); - list_del_init(invalid_list); + /* + * wmb: make sure everyone sees our modifications to the page tables + * rmb: make sure we see changes to vcpu->mode + */ + smp_mb(); - trace_kvm_mmu_delay_free_pages(sp); - call_rcu(&sp->rcu, free_pages_rcu); - return; - } + /* + * Wait for all vcpus to exit guest mode and/or lockless shadow + * page table walks. + */ + kvm_flush_remote_tlbs(kvm); do { sp = list_first_entry(invalid_list, struct kvm_mmu_page, link); @@ -2039,7 +2025,6 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, kvm_mmu_isolate_page(sp); kvm_mmu_free_page(sp); } while (!list_empty(invalid_list)); - } /* diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index cae342d..c446435 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -128,7 +128,8 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu); enum { OUTSIDE_GUEST_MODE, IN_GUEST_MODE, - EXITING_GUEST_MODE + EXITING_GUEST_MODE, + READING_SHADOW_PAGE_TABLES, }; /* |