diff options
Diffstat (limited to 'arch/x86/kvm/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 120 |
1 files changed, 93 insertions, 27 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 8f72526e2f68..a63964e7cec7 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2095,6 +2095,12 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct if (!direct) sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache); set_page_private(virt_to_page(sp->spt), (unsigned long)sp); + + /* + * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() + * depends on valid pages being added to the head of the list. See + * comments in kvm_zap_obsolete_pages(). + */ list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages); kvm_mod_used_mmu_pages(vcpu->kvm, +1); return sp; @@ -2244,7 +2250,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, #define for_each_valid_sp(_kvm, _sp, _gfn) \ hlist_for_each_entry(_sp, \ &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \ - if ((_sp)->role.invalid) { \ + if (is_obsolete_sp((_kvm), (_sp)) || (_sp)->role.invalid) { \ } else #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ @@ -2301,6 +2307,11 @@ static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { } static void mmu_audit_disable(void) { } #endif +static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + return unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); +} + static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, struct list_head *invalid_list) { @@ -2525,6 +2536,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, if (level > PT_PAGE_TABLE_LEVEL && need_sync) flush |= kvm_sync_pages(vcpu, gfn, &invalid_list); } + sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen; clear_page(sp->spt); trace_kvm_mmu_get_page(sp, true); @@ -3466,7 +3478,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level, /* * Currently, fast page fault only works for direct mapping * since the gfn is not stable for indirect shadow page. See - * Documentation/virtual/kvm/locking.txt to get more detail. + * Documentation/virt/kvm/locking.txt to get more detail. */ fault_handled = fast_pf_fix_direct_spte(vcpu, sp, iterator.sptep, spte, @@ -4233,6 +4245,13 @@ static bool fast_cr3_switch(struct kvm_vcpu *vcpu, gpa_t new_cr3, return false; if (cached_root_available(vcpu, new_cr3, new_role)) { + /* + * It is possible that the cached previous root page is + * obsolete because of a change in the MMU generation + * number. However, changing the generation number is + * accompanied by KVM_REQ_MMU_RELOAD, which will free + * the root set here and allocate a new one. + */ kvm_make_request(KVM_REQ_LOAD_CR3, vcpu); if (!skip_tlb_flush) { kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); @@ -5649,44 +5668,91 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) return alloc_mmu_pages(vcpu); } -static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, - struct kvm_memory_slot *slot, - struct kvm_page_track_notifier_node *node) + +static void kvm_zap_obsolete_pages(struct kvm *kvm) { - struct kvm_mmu_page *sp; + struct kvm_mmu_page *sp, *node; LIST_HEAD(invalid_list); - unsigned long i; - bool flush; - gfn_t gfn; - - spin_lock(&kvm->mmu_lock); - - if (list_empty(&kvm->arch.active_mmu_pages)) - goto out_unlock; - - flush = slot_handle_all_level(kvm, slot, kvm_zap_rmapp, false); + int ign; - for (i = 0; i < slot->npages; i++) { - gfn = slot->base_gfn + i; +restart: + list_for_each_entry_safe_reverse(sp, node, + &kvm->arch.active_mmu_pages, link) { + /* + * No obsolete valid page exists before a newly created page + * since active_mmu_pages is a FIFO list. + */ + if (!is_obsolete_sp(kvm, sp)) + break; - for_each_valid_sp(kvm, sp, gfn) { - if (sp->gfn != gfn) - continue; + /* + * Do not repeatedly zap a root page to avoid unnecessary + * KVM_REQ_MMU_RELOAD, otherwise we may not be able to + * progress: + * vcpu 0 vcpu 1 + * call vcpu_enter_guest(): + * 1): handle KVM_REQ_MMU_RELOAD + * and require mmu-lock to + * load mmu + * repeat: + * 1): zap root page and + * send KVM_REQ_MMU_RELOAD + * + * 2): if (cond_resched_lock(mmu-lock)) + * + * 2): hold mmu-lock and load mmu + * + * 3): see KVM_REQ_MMU_RELOAD bit + * on vcpu->requests is set + * then return 1 to call + * vcpu_enter_guest() again. + * goto repeat; + * + * Since we are reversely walking the list and the invalid + * list will be moved to the head, skip the invalid page + * can help us to avoid the infinity list walking. + */ + if (sp->role.invalid) + continue; - kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); - } if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { - kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); - flush = false; + kvm_mmu_commit_zap_page(kvm, &invalid_list); cond_resched_lock(&kvm->mmu_lock); + goto restart; } + + if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign)) + goto restart; } - kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); -out_unlock: + kvm_mmu_commit_zap_page(kvm, &invalid_list); +} + +/* + * Fast invalidate all shadow pages and use lock-break technique + * to zap obsolete pages. + * + * It's required when memslot is being deleted or VM is being + * destroyed, in these cases, we should ensure that KVM MMU does + * not use any resource of the being-deleted slot or all slots + * after calling the function. + */ +static void kvm_mmu_zap_all_fast(struct kvm *kvm) +{ + spin_lock(&kvm->mmu_lock); + kvm->arch.mmu_valid_gen++; + + kvm_zap_obsolete_pages(kvm); spin_unlock(&kvm->mmu_lock); } +static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot, + struct kvm_page_track_notifier_node *node) +{ + kvm_mmu_zap_all_fast(kvm); +} + void kvm_mmu_init_vm(struct kvm *kvm) { struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; |