KVM: x86/mmu: Use an rwlock for the x86 MMU

Add a read / write lock to be used in place of the MMU spinlock on x86.
The rwlock will enable the TDP MMU to handle page faults, and other
operations in parallel in future commits.
Reviewed-by: NPeter Feiner <pfeiner@google.com>
Signed-off-by: NBen Gardon <bgardon@google.com>

Message-Id: <20210202185734.1680553-19-bgardon@google.com>
[Introduce virt/kvm/mmu_lock.h - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -348,6 +348,8 @@ struct kvm_mmu_root_info {
 
 #define KVM_MMU_NUM_PREV_ROOTS 3
 
+#define KVM_HAVE_MMU_RWLOCK
+
 struct kvm_mmu_page;
 
 /*

arch/x86/kvm/mmu/mmu.c

@@ -2010,9 +2010,9 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu,
 			flush |= kvm_sync_page(vcpu, sp, &invalid_list);
 			mmu_pages_clear_parents(&parents);
 		}
-		if (need_resched() || spin_needbreak(&vcpu->kvm->mmu_lock)) {
+		if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) {
 			kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
-			cond_resched_lock(&vcpu->kvm->mmu_lock);
+			cond_resched_rwlock_write(&vcpu->kvm->mmu_lock);
 			flush = false;
 		}
 	}
@@ -2464,7 +2464,7 @@ static int make_mmu_pages_available(struct kvm_vcpu *vcpu)
  */
 void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages)
 {
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 
 	if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) {
 		kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages -
@@ -2475,7 +2475,7 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages)
 
 	kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages;
 
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 
 int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
@@ -2486,7 +2486,7 @@ int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
 
 	pgprintk("%s: looking for gfn %llx\n", __func__, gfn);
 	r = 0;
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	for_each_gfn_indirect_valid_sp(kvm, sp, gfn) {
 		pgprintk("%s: gfn %llx role %x\n", __func__, gfn,
 			 sp->role.word);
@@ -2494,7 +2494,7 @@ int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
 		kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
 	}
 	kvm_mmu_commit_zap_page(kvm, &invalid_list);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 
 	return r;
 }
@@ -3186,7 +3186,7 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 			return;
 	}
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 
 	for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
 		if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i))
@@ -3209,7 +3209,7 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
 	}
 
 	kvm_mmu_commit_zap_page(kvm, &invalid_list);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_free_roots);
 
@@ -3230,16 +3230,16 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
 {
 	struct kvm_mmu_page *sp;
 
-	spin_lock(&vcpu->kvm->mmu_lock);
+	write_lock(&vcpu->kvm->mmu_lock);
 
 	if (make_mmu_pages_available(vcpu)) {
-		spin_unlock(&vcpu->kvm->mmu_lock);
+		write_unlock(&vcpu->kvm->mmu_lock);
 		return INVALID_PAGE;
 	}
 	sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
 	++sp->root_count;
 
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	write_unlock(&vcpu->kvm->mmu_lock);
 	return __pa(sp->spt);
 }
 
@@ -3410,17 +3410,17 @@ void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
 		    !smp_load_acquire(&sp->unsync_children))
 			return;
 
-		spin_lock(&vcpu->kvm->mmu_lock);
+		write_lock(&vcpu->kvm->mmu_lock);
 		kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
 
 		mmu_sync_children(vcpu, sp);
 
 		kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
-		spin_unlock(&vcpu->kvm->mmu_lock);
+		write_unlock(&vcpu->kvm->mmu_lock);
 		return;
 	}
 
-	spin_lock(&vcpu->kvm->mmu_lock);
+	write_lock(&vcpu->kvm->mmu_lock);
 	kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC);
 
 	for (i = 0; i < 4; ++i) {
@@ -3434,7 +3434,7 @@ void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu)
 	}
 
 	kvm_mmu_audit(vcpu, AUDIT_POST_SYNC);
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	write_unlock(&vcpu->kvm->mmu_lock);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_sync_roots);
 
@@ -3718,7 +3718,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		return r;
 
 	r = RET_PF_RETRY;
-	spin_lock(&vcpu->kvm->mmu_lock);
+	write_lock(&vcpu->kvm->mmu_lock);
 	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
 		goto out_unlock;
 	r = make_mmu_pages_available(vcpu);
@@ -3733,7 +3733,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 				 prefault, is_tdp);
 
 out_unlock:
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	write_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
 	return r;
 }
@@ -4959,7 +4959,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
 	 */
 	mmu_topup_memory_caches(vcpu, true);
 
-	spin_lock(&vcpu->kvm->mmu_lock);
+	write_lock(&vcpu->kvm->mmu_lock);
 
 	gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes);
 
@@ -4991,7 +4991,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
 	}
 	kvm_mmu_flush_or_zap(vcpu, &invalid_list, remote_flush, local_flush);
 	kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE);
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	write_unlock(&vcpu->kvm->mmu_lock);
 }
 
 int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
@@ -5189,14 +5189,14 @@ slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot,
 		if (iterator.rmap)
 			flush |= fn(kvm, iterator.rmap);
 
-		if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
+		if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) {
 			if (flush && lock_flush_tlb) {
 				kvm_flush_remote_tlbs_with_address(kvm,
 						start_gfn,
 						iterator.gfn - start_gfn + 1);
 				flush = false;
 			}
-			cond_resched_lock(&kvm->mmu_lock);
+			cond_resched_rwlock_write(&kvm->mmu_lock);
 		}
 	}
 
@@ -5346,7 +5346,7 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm)
 		 * be in active use by the guest.
 		 */
 		if (batch >= BATCH_ZAP_PAGES &&
-		    cond_resched_lock(&kvm->mmu_lock)) {
+		    cond_resched_rwlock_write(&kvm->mmu_lock)) {
 			batch = 0;
 			goto restart;
 		}
@@ -5379,7 +5379,7 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm)
 {
 	lockdep_assert_held(&kvm->slots_lock);
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	trace_kvm_mmu_zap_all_fast(kvm);
 
 	/*
@@ -5406,7 +5406,7 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm)
 	if (kvm->arch.tdp_mmu_enabled)
 		kvm_tdp_mmu_zap_all(kvm);
 
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 
 static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
@@ -5448,7 +5448,7 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 	int i;
 	bool flush;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
 		slots = __kvm_memslots(kvm, i);
 		kvm_for_each_memslot(memslot, slots) {
@@ -5472,7 +5472,7 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 			kvm_flush_remote_tlbs(kvm);
 	}
 
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 
 static bool slot_rmap_write_protect(struct kvm *kvm,
@@ -5487,12 +5487,12 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
 {
 	bool flush;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect,
 				start_level, KVM_MAX_HUGEPAGE_LEVEL, false);
 	if (kvm->arch.tdp_mmu_enabled)
 		flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, PG_LEVEL_4K);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 
 	/*
 	 * We can flush all the TLBs out of the mmu lock without TLB
@@ -5552,13 +5552,13 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
 				   const struct kvm_memory_slot *memslot)
 {
 	/* FIXME: const-ify all uses of struct kvm_memory_slot.  */
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot,
 			 kvm_mmu_zap_collapsible_spte, true);
 
 	if (kvm->arch.tdp_mmu_enabled)
 		kvm_tdp_mmu_zap_collapsible_sptes(kvm, memslot);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 
 void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
@@ -5581,11 +5581,11 @@ void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
 {
 	bool flush;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, false);
 	if (kvm->arch.tdp_mmu_enabled)
 		flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 
 	/*
 	 * It's also safe to flush TLBs out of mmu lock here as currently this
@@ -5603,12 +5603,12 @@ void kvm_mmu_slot_largepage_remove_write_access(struct kvm *kvm,
 {
 	bool flush;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	flush = slot_handle_large_level(kvm, memslot, slot_rmap_write_protect,
 					false);
 	if (kvm->arch.tdp_mmu_enabled)
 		flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, PG_LEVEL_2M);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 
 	if (flush)
 		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
@@ -5620,11 +5620,11 @@ void kvm_mmu_slot_set_dirty(struct kvm *kvm,
 {
 	bool flush;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	flush = slot_handle_all_level(kvm, memslot, __rmap_set_dirty, false);
 	if (kvm->arch.tdp_mmu_enabled)
 		flush |= kvm_tdp_mmu_slot_set_dirty(kvm, memslot);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 
 	if (flush)
 		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
@@ -5637,14 +5637,14 @@ void kvm_mmu_zap_all(struct kvm *kvm)
 	LIST_HEAD(invalid_list);
 	int ign;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 restart:
 	list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) {
 		if (WARN_ON(sp->role.invalid))
 			continue;
 		if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign))
 			goto restart;
-		if (cond_resched_lock(&kvm->mmu_lock))
+		if (cond_resched_rwlock_write(&kvm->mmu_lock))
 			goto restart;
 	}
 
@@ -5653,7 +5653,7 @@ void kvm_mmu_zap_all(struct kvm *kvm)
 	if (kvm->arch.tdp_mmu_enabled)
 		kvm_tdp_mmu_zap_all(kvm);
 
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 
 void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen)
@@ -5713,7 +5713,7 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 			continue;
 
 		idx = srcu_read_lock(&kvm->srcu);
-		spin_lock(&kvm->mmu_lock);
+		write_lock(&kvm->mmu_lock);
 
 		if (kvm_has_zapped_obsolete_pages(kvm)) {
 			kvm_mmu_commit_zap_page(kvm,
@@ -5724,7 +5724,7 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 		freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan);
 
 unlock:
-		spin_unlock(&kvm->mmu_lock);
+		write_unlock(&kvm->mmu_lock);
 		srcu_read_unlock(&kvm->srcu, idx);
 
 		/*
@@ -5944,7 +5944,7 @@ static void kvm_recover_nx_lpages(struct kvm *kvm)
 	ulong to_zap;
 
 	rcu_idx = srcu_read_lock(&kvm->srcu);
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 
 	ratio = READ_ONCE(nx_huge_pages_recovery_ratio);
 	to_zap = ratio ? DIV_ROUND_UP(kvm->stat.nx_lpage_splits, ratio) : 0;
@@ -5969,14 +5969,14 @@ static void kvm_recover_nx_lpages(struct kvm *kvm)
 			WARN_ON_ONCE(sp->lpage_disallowed);
 		}
 
-		if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
+		if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) {
 			kvm_mmu_commit_zap_page(kvm, &invalid_list);
-			cond_resched_lock(&kvm->mmu_lock);
+			cond_resched_rwlock_write(&kvm->mmu_lock);
 		}
 	}
 	kvm_mmu_commit_zap_page(kvm, &invalid_list);
 
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 	srcu_read_unlock(&kvm->srcu, rcu_idx);
 }
 

arch/x86/kvm/mmu/page_track.c

@@ -184,9 +184,9 @@ kvm_page_track_register_notifier(struct kvm *kvm,
 
 	head = &kvm->arch.track_notifier_head;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	hlist_add_head_rcu(&n->node, &head->track_notifier_list);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 }
 EXPORT_SYMBOL_GPL(kvm_page_track_register_notifier);
 
@@ -202,9 +202,9 @@ kvm_page_track_unregister_notifier(struct kvm *kvm,
 
 	head = &kvm->arch.track_notifier_head;
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 	hlist_del_rcu(&n->node);
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 	synchronize_srcu(&head->track_srcu);
 }
 EXPORT_SYMBOL_GPL(kvm_page_track_unregister_notifier);

arch/x86/kvm/mmu/paging_tmpl.h

@@ -868,7 +868,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,
 	}
 
 	r = RET_PF_RETRY;
-	spin_lock(&vcpu->kvm->mmu_lock);
+	write_lock(&vcpu->kvm->mmu_lock);
 	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
 		goto out_unlock;
 
@@ -881,7 +881,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code,
 	kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
 
 out_unlock:
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	write_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
 	return r;
 }
@@ -919,7 +919,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa)
 		return;
 	}
 
-	spin_lock(&vcpu->kvm->mmu_lock);
+	write_lock(&vcpu->kvm->mmu_lock);
 	for_each_shadow_entry_using_root(vcpu, root_hpa, gva, iterator) {
 		level = iterator.level;
 		sptep = iterator.sptep;
@@ -954,7 +954,7 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva, hpa_t root_hpa)
 		if (!is_shadow_present_pte(*sptep) || !sp->unsync_children)
 			break;
 	}
-	spin_unlock(&vcpu->kvm->mmu_lock);
+	write_unlock(&vcpu->kvm->mmu_lock);
 }
 
 /* Note, @addr is a GPA when gva_to_gpa() translates an L2 GPA to an L1 GPA. */

arch/x86/kvm/mmu/tdp_mmu.c

@@ -59,7 +59,7 @@ static void tdp_mmu_put_root(struct kvm *kvm, struct kvm_mmu_page *root)
 static inline bool tdp_mmu_next_root_valid(struct kvm *kvm,
 					   struct kvm_mmu_page *root)
 {
-	lockdep_assert_held(&kvm->mmu_lock);
+	lockdep_assert_held_write(&kvm->mmu_lock);
 
 	if (list_entry_is_head(root, &kvm->arch.tdp_mmu_roots, link))
 		return false;
@@ -117,7 +117,7 @@ void kvm_tdp_mmu_free_root(struct kvm *kvm, struct kvm_mmu_page *root)
 {
 	gfn_t max_gfn = 1ULL << (shadow_phys_bits - PAGE_SHIFT);
 
-	lockdep_assert_held(&kvm->mmu_lock);
+	lockdep_assert_held_write(&kvm->mmu_lock);
 
 	WARN_ON(root->root_count);
 	WARN_ON(!root->tdp_mmu_page);
@@ -170,13 +170,13 @@ static struct kvm_mmu_page *get_tdp_mmu_vcpu_root(struct kvm_vcpu *vcpu)
 
 	role = page_role_for_level(vcpu, vcpu->arch.mmu->shadow_root_level);
 
-	spin_lock(&kvm->mmu_lock);
+	write_lock(&kvm->mmu_lock);
 
 	/* Check for an existing root before allocating a new one. */
 	for_each_tdp_mmu_root(kvm, root) {
 		if (root->role.word == role.word) {
 			kvm_mmu_get_root(kvm, root);
-			spin_unlock(&kvm->mmu_lock);
+			write_unlock(&kvm->mmu_lock);
 			return root;
 		}
 	}
@@ -186,7 +186,7 @@ static struct kvm_mmu_page *get_tdp_mmu_vcpu_root(struct kvm_vcpu *vcpu)
 
 	list_add(&root->link, &kvm->arch.tdp_mmu_roots);
 
-	spin_unlock(&kvm->mmu_lock);
+	write_unlock(&kvm->mmu_lock);
 
 	return root;
 }
@@ -421,7 +421,7 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
 	struct kvm_mmu_page *root = sptep_to_sp(root_pt);
 	int as_id = kvm_mmu_page_as_id(root);
 
-	lockdep_assert_held(&kvm->mmu_lock);
+	lockdep_assert_held_write(&kvm->mmu_lock);
 
 	WRITE_ONCE(*rcu_dereference(iter->sptep), new_spte);
 
@@ -492,13 +492,13 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm,
 	if (iter->next_last_level_gfn == iter->yielded_gfn)
 		return false;
 
-	if (need_resched() || spin_needbreak(&kvm->mmu_lock)) {
+	if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) {
 		rcu_read_unlock();
 
 		if (flush)
 			kvm_flush_remote_tlbs(kvm);
 
-		cond_resched_lock(&kvm->mmu_lock);
+		cond_resched_rwlock_write(&kvm->mmu_lock);
 		rcu_read_lock();
 
 		WARN_ON(iter->gfn > iter->next_last_level_gfn);
@@ -1103,7 +1103,7 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
 	struct kvm_mmu_page *root;
 	int root_as_id;
 
-	lockdep_assert_held(&kvm->mmu_lock);
+	lockdep_assert_held_write(&kvm->mmu_lock);
 	for_each_tdp_mmu_root(kvm, root) {
 		root_as_id = kvm_mmu_page_as_id(root);
 		if (root_as_id != slot->as_id)
@@ -1268,7 +1268,7 @@ bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm,
 	int root_as_id;
 	bool spte_set = false;
 
-	lockdep_assert_held(&kvm->mmu_lock);
+	lockdep_assert_held_write(&kvm->mmu_lock);
 	for_each_tdp_mmu_root(kvm, root) {
 		root_as_id = kvm_mmu_page_as_id(root);
 		if (root_as_id != slot->as_id)

arch/x86/kvm/x86.c

@@ -7112,9 +7112,9 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 	if (vcpu->arch.mmu->direct_map) {
 		unsigned int indirect_shadow_pages;
 
-		spin_lock(&vcpu->kvm->mmu_lock);
+		write_lock(&vcpu->kvm->mmu_lock);
 		indirect_shadow_pages = vcpu->kvm->arch.indirect_shadow_pages;
-		spin_unlock(&vcpu->kvm->mmu_lock);
+		write_unlock(&vcpu->kvm->mmu_lock);
 
 		if (indirect_shadow_pages)
 			kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(gpa));

include/linux/kvm_host.h

@@ -451,7 +451,12 @@ struct kvm_memslots {
 };
 
 struct kvm {
+#ifdef KVM_HAVE_MMU_RWLOCK
+	rwlock_t mmu_lock;
+#else
 	spinlock_t mmu_lock;
+#endif /* KVM_HAVE_MMU_RWLOCK */
+
 	struct mutex slots_lock;
 	struct mm_struct *mm; /* userspace tied to this vm */
 	struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM];

virt/kvm/dirty_ring.c

@@ -9,6 +9,7 @@
 #include <linux/vmalloc.h>
 #include <linux/kvm_dirty_ring.h>
 #include <trace/events/kvm.h>
+#include "mmu_lock.h"
 
 int __weak kvm_cpu_dirty_log_size(void)
 {
@@ -60,9 +61,9 @@ static void kvm_reset_dirty_gfn(struct kvm *kvm, u32 slot, u64 offset, u64 mask)
 	if (!memslot || (offset + __fls(mask)) >= memslot->npages)
 		return;
 
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 	kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, offset, mask);
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 }
 
 int kvm_dirty_ring_alloc(struct kvm_dirty_ring *ring, int index, u32 size)

virt/kvm/kvm_main.c

@@ -58,6 +58,7 @@
 
 #include "coalesced_mmio.h"
 #include "async_pf.h"
+#include "mmu_lock.h"
 #include "vfio.h"
 
 #define CREATE_TRACE_POINTS
@@ -459,13 +460,15 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
 	int idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
-	spin_lock(&kvm->mmu_lock);
+
+	KVM_MMU_LOCK(kvm);
+
 	kvm->mmu_notifier_seq++;
 
 	if (kvm_set_spte_hva(kvm, address, pte))
 		kvm_flush_remote_tlbs(kvm);
 
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
 }
 
@@ -476,7 +479,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 	int need_tlb_flush = 0, idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 	/*
 	 * The count increase must become visible at unlock time as no
 	 * spte can be established without taking the mmu_lock and
@@ -489,7 +492,7 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 	if (need_tlb_flush || kvm->tlbs_dirty)
 		kvm_flush_remote_tlbs(kvm);
 
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return 0;
@@ -500,7 +503,7 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
 
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 	/*
 	 * This sequence increase will notify the kvm page fault that
 	 * the page that is going to be mapped in the spte could have
@@ -514,7 +517,7 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn,
 	 * in conjunction with the smp_rmb in mmu_notifier_retry().
 	 */
 	kvm->mmu_notifier_count--;
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 
 	BUG_ON(kvm->mmu_notifier_count < 0);
 }
@@ -528,13 +531,13 @@ static int kvm_mmu_notifier_clear_flush_young(struct mmu_notifier *mn,
 	int young, idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 
 	young = kvm_age_hva(kvm, start, end);
 	if (young)
 		kvm_flush_remote_tlbs(kvm);
 
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return young;
@@ -549,7 +552,7 @@ static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
 	int young, idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 	/*
 	 * Even though we do not flush TLB, this will still adversely
 	 * affect performance on pre-Haswell Intel EPT, where there is
@@ -564,7 +567,7 @@ static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn,
 	 * more sophisticated heuristic later.
 	 */
 	young = kvm_age_hva(kvm, start, end);
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return young;
@@ -578,9 +581,9 @@ static int kvm_mmu_notifier_test_young(struct mmu_notifier *mn,
 	int young, idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 	young = kvm_test_age_hva(kvm, address);
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 	srcu_read_unlock(&kvm->srcu, idx);
 
 	return young;
@@ -745,7 +748,7 @@ static struct kvm *kvm_create_vm(unsigned long type)
 	if (!kvm)
 		return ERR_PTR(-ENOMEM);
 
-	spin_lock_init(&kvm->mmu_lock);
+	KVM_MMU_LOCK_INIT(kvm);
 	mmgrab(current->mm);
 	kvm->mm = current->mm;
 	kvm_eventfd_init(kvm);
@@ -1525,7 +1528,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
 		dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
 		memset(dirty_bitmap_buffer, 0, n);
 
-		spin_lock(&kvm->mmu_lock);
+		KVM_MMU_LOCK(kvm);
 		for (i = 0; i < n / sizeof(long); i++) {
 			unsigned long mask;
 			gfn_t offset;
@@ -1541,7 +1544,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
 			kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
 								offset, mask);
 		}
-		spin_unlock(&kvm->mmu_lock);
+		KVM_MMU_UNLOCK(kvm);
 	}
 
 	if (flush)
@@ -1636,7 +1639,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
 	if (copy_from_user(dirty_bitmap_buffer, log->dirty_bitmap, n))
 		return -EFAULT;
 
-	spin_lock(&kvm->mmu_lock);
+	KVM_MMU_LOCK(kvm);
 	for (offset = log->first_page, i = offset / BITS_PER_LONG,
 		 n = DIV_ROUND_UP(log->num_pages, BITS_PER_LONG); n--;
 	     i++, offset += BITS_PER_LONG) {
@@ -1659,7 +1662,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
 								offset, mask);
 		}
 	}
-	spin_unlock(&kvm->mmu_lock);
+	KVM_MMU_UNLOCK(kvm);
 
 	if (flush)
 		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);

virt/kvm/mmu_lock.h

+// SPDX-License-Identifier: GPL-2.0-only
+
+#ifndef KVM_MMU_LOCK_H
+#define KVM_MMU_LOCK_H 1
+
+/*
+ * Architectures can choose whether to use an rwlock or spinlock
+ * for the mmu_lock.  These macros, for use in common code
+ * only, avoids using #ifdefs in places that must deal with
+ * multiple architectures.
+ */
+
+#ifdef KVM_HAVE_MMU_RWLOCK
+#define KVM_MMU_LOCK_INIT(kvm) rwlock_init(&(kvm)->mmu_lock)
+#define KVM_MMU_LOCK(kvm)      write_lock(&(kvm)->mmu_lock)
+#define KVM_MMU_UNLOCK(kvm)    write_unlock(&(kvm)->mmu_lock)
+#else
+#define KVM_MMU_LOCK_INIT(kvm) spin_lock_init(&(kvm)->mmu_lock)
+#define KVM_MMU_LOCK(kvm)      spin_lock(&(kvm)->mmu_lock)
+#define KVM_MMU_UNLOCK(kvm)    spin_unlock(&(kvm)->mmu_lock)
+#endif /* KVM_HAVE_MMU_RWLOCK */
+
+#endif