1 files changed, 270 insertions, 166 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 00268290dcbd..67ae2d5c37b2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -104,16 +104,16 @@ static cpumask_var_t cpus_hardware_enabled;
 static int kvm_usage_count;
 static atomic_t hardware_enable_failed;
 
-struct kmem_cache *kvm_vcpu_cache;
-EXPORT_SYMBOL_GPL(kvm_vcpu_cache);
+static struct kmem_cache *kvm_vcpu_cache;
 
 static __read_mostly struct preempt_ops kvm_preempt_ops;
+static DEFINE_PER_CPU(struct kvm_vcpu *, kvm_running_vcpu);
 
 struct dentry *kvm_debugfs_dir;
 EXPORT_SYMBOL_GPL(kvm_debugfs_dir);
 
 static int kvm_debugfs_num_entries;
-static const struct file_operations *stat_fops_per_vm[];
+static const struct file_operations stat_fops_per_vm;
 
 static long kvm_vcpu_ioctl(struct file *file, unsigned int ioctl,
 			   unsigned long arg);
@@ -186,17 +186,30 @@ bool kvm_is_reserved_pfn(kvm_pfn_t pfn)
 	 */
 	if (pfn_valid(pfn))
 		return PageReserved(pfn_to_page(pfn)) &&
+		       !is_zero_pfn(pfn) &&
 		       !kvm_is_zone_device_pfn(pfn);
 
 	return true;
 }
 
+bool kvm_is_transparent_hugepage(kvm_pfn_t pfn)
+{
+	struct page *page = pfn_to_page(pfn);
+
+	if (!PageTransCompoundMap(page))
+		return false;
+
+	return is_transparent_hugepage(compound_head(page));
+}
+
 /*
  * Switches to specified vcpu, until a matching vcpu_put()
  */
 void vcpu_load(struct kvm_vcpu *vcpu)
 {
 	int cpu = get_cpu();
+
+	__this_cpu_write(kvm_running_vcpu, vcpu);
 	preempt_notifier_register(&vcpu->preempt_notifier);
 	kvm_arch_vcpu_load(vcpu, cpu);
 	put_cpu();
@@ -208,6 +221,7 @@ void vcpu_put(struct kvm_vcpu *vcpu)
 	preempt_disable();
 	kvm_arch_vcpu_put(vcpu);
 	preempt_notifier_unregister(&vcpu->preempt_notifier);
+	__this_cpu_write(kvm_running_vcpu, NULL);
 	preempt_enable();
 }
 EXPORT_SYMBOL_GPL(vcpu_put);
@@ -322,11 +336,8 @@ void kvm_reload_remote_mmus(struct kvm *kvm)
 	kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_RELOAD);
 }
 
-int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
+static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 {
-	struct page *page;
-	int r;
-
 	mutex_init(&vcpu->mutex);
 	vcpu->cpu = -1;
 	vcpu->kvm = kvm;
@@ -338,42 +349,28 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 	vcpu->pre_pcpu = -1;
 	INIT_LIST_HEAD(&vcpu->blocked_vcpu_list);
 
-	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
-	if (!page) {
-		r = -ENOMEM;
-		goto fail;
-	}
-	vcpu->run = page_address(page);
-
 	kvm_vcpu_set_in_spin_loop(vcpu, false);
 	kvm_vcpu_set_dy_eligible(vcpu, false);
 	vcpu->preempted = false;
 	vcpu->ready = false;
-
-	r = kvm_arch_vcpu_init(vcpu);
-	if (r < 0)
-		goto fail_free_run;
-	return 0;
-
-fail_free_run:
-	free_page((unsigned long)vcpu->run);
-fail:
-	return r;
+	preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
 }
-EXPORT_SYMBOL_GPL(kvm_vcpu_init);
 
-void kvm_vcpu_uninit(struct kvm_vcpu *vcpu)
+void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
+	kvm_arch_vcpu_destroy(vcpu);
+
 	/*
-	 * no need for rcu_read_lock as VCPU_RUN is the only place that
-	 * will change the vcpu->pid pointer and on uninit all file
-	 * descriptors are already gone.
+	 * No need for rcu_read_lock as VCPU_RUN is the only place that changes
+	 * the vcpu->pid pointer, and at destruction time all file descriptors
+	 * are already gone.
 	 */
 	put_pid(rcu_dereference_protected(vcpu->pid, 1));
-	kvm_arch_vcpu_uninit(vcpu);
+
 	free_page((unsigned long)vcpu->run);
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
-EXPORT_SYMBOL_GPL(kvm_vcpu_uninit);
+EXPORT_SYMBOL_GPL(kvm_vcpu_destroy);
 
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
 static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn)
@@ -650,11 +647,11 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 			return -ENOMEM;
 
 		stat_data->kvm = kvm;
-		stat_data->offset = p->offset;
-		stat_data->mode = p->mode ? p->mode : 0644;
+		stat_data->dbgfs_item = p;
 		kvm->debugfs_stat_data[p - debugfs_entries] = stat_data;
-		debugfs_create_file(p->name, stat_data->mode, kvm->debugfs_dentry,
-				    stat_data, stat_fops_per_vm[p->kind]);
+		debugfs_create_file(p->name, KVM_DBGFS_GET_MODE(p),
+				    kvm->debugfs_dentry, stat_data,
+				    &stat_fops_per_vm);
 	}
 	return 0;
 }
@@ -964,7 +961,7 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 
 	/*
 	 * Increment the new memslot generation a second time, dropping the
-	 * update in-progress flag and incrementing then generation based on
+	 * update in-progress flag and incrementing the generation based on
 	 * the number of address spaces.  This provides a unique and easily
 	 * identifiable generation number while the memslots are in flux.
 	 */
@@ -1117,7 +1114,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		 *
 		 * validation of sp->gfn happens in:
 		 *	- gfn_to_hva (kvm_read_guest, gfn_to_pfn)
-		 *	- kvm_is_visible_gfn (mmu_check_roots)
+		 *	- kvm_is_visible_gfn (mmu_check_root)
 		 */
 		kvm_arch_flush_shadow_memslot(kvm, slot);
 
@@ -1406,14 +1403,14 @@ bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
 
-unsigned long kvm_host_page_size(struct kvm *kvm, gfn_t gfn)
+unsigned long kvm_host_page_size(struct kvm_vcpu *vcpu, gfn_t gfn)
 {
 	struct vm_area_struct *vma;
 	unsigned long addr, size;
 
 	size = PAGE_SIZE;
 
-	addr = gfn_to_hva(kvm, gfn);
+	addr = kvm_vcpu_gfn_to_hva_prot(vcpu, gfn, NULL);
 	if (kvm_is_error_hva(addr))
 		return PAGE_SIZE;
 
@@ -1519,7 +1516,7 @@ static inline int check_user_page_hwpoison(unsigned long addr)
 /*
  * The fast path to get the writable pfn which will be stored in @pfn,
  * true indicates success, otherwise false is returned.  It's also the
- * only part that runs if we can are in atomic context.
+ * only part that runs if we can in atomic context.
  */
 static bool hva_to_pfn_fast(unsigned long addr, bool write_fault,
 			    bool *writable, kvm_pfn_t *pfn)
@@ -1821,26 +1818,72 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
 }
 EXPORT_SYMBOL_GPL(gfn_to_page);
 
-static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
-			 struct kvm_host_map *map)
+void kvm_release_pfn(kvm_pfn_t pfn, bool dirty, struct gfn_to_pfn_cache *cache)
+{
+	if (pfn == 0)
+		return;
+
+	if (cache)
+		cache->pfn = cache->gfn = 0;
+
+	if (dirty)
+		kvm_release_pfn_dirty(pfn);
+	else
+		kvm_release_pfn_clean(pfn);
+}
+
+static void kvm_cache_gfn_to_pfn(struct kvm_memory_slot *slot, gfn_t gfn,
+				 struct gfn_to_pfn_cache *cache, u64 gen)
+{
+	kvm_release_pfn(cache->pfn, cache->dirty, cache);
+
+	cache->pfn = gfn_to_pfn_memslot(slot, gfn);
+	cache->gfn = gfn;
+	cache->dirty = false;
+	cache->generation = gen;
+}
+
+static int __kvm_map_gfn(struct kvm_memslots *slots, gfn_t gfn,
+			 struct kvm_host_map *map,
+			 struct gfn_to_pfn_cache *cache,
+			 bool atomic)
 {
 	kvm_pfn_t pfn;
 	void *hva = NULL;
 	struct page *page = KVM_UNMAPPED_PAGE;
+	struct kvm_memory_slot *slot = __gfn_to_memslot(slots, gfn);
+	u64 gen = slots->generation;
 
 	if (!map)
 		return -EINVAL;
 
-	pfn = gfn_to_pfn_memslot(slot, gfn);
+	if (cache) {
+		if (!cache->pfn || cache->gfn != gfn ||
+			cache->generation != gen) {
+			if (atomic)
+				return -EAGAIN;
+			kvm_cache_gfn_to_pfn(slot, gfn, cache, gen);
+		}
+		pfn = cache->pfn;
+	} else {
+		if (atomic)
+			return -EAGAIN;
+		pfn = gfn_to_pfn_memslot(slot, gfn);
+	}
 	if (is_error_noslot_pfn(pfn))
 		return -EINVAL;
 
 	if (pfn_valid(pfn)) {
 		page = pfn_to_page(pfn);
-		hva = kmap(page);
+		if (atomic)
+			hva = kmap_atomic(page);
+		else
+			hva = kmap(page);
 #ifdef CONFIG_HAS_IOMEM
-	} else {
+	} else if (!atomic) {
 		hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
+	} else {
+		return -EINVAL;
 #endif
 	}
 
@@ -1855,14 +1898,25 @@ static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
 	return 0;
 }
 
+int kvm_map_gfn(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map,
+		struct gfn_to_pfn_cache *cache, bool atomic)
+{
+	return __kvm_map_gfn(kvm_memslots(vcpu->kvm), gfn, map,
+			cache, atomic);
+}
+EXPORT_SYMBOL_GPL(kvm_map_gfn);
+
 int kvm_vcpu_map(struct kvm_vcpu *vcpu, gfn_t gfn, struct kvm_host_map *map)
 {
-	return __kvm_map_gfn(kvm_vcpu_gfn_to_memslot(vcpu, gfn), gfn, map);
+	return __kvm_map_gfn(kvm_vcpu_memslots(vcpu), gfn, map,
+		NULL, false);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_map);
 
-void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
-		    bool dirty)
+static void __kvm_unmap_gfn(struct kvm_memory_slot *memslot,
+			struct kvm_host_map *map,
+			struct gfn_to_pfn_cache *cache,
+			bool dirty, bool atomic)
 {
 	if (!map)
 		return;
@@ -1870,23 +1924,45 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
 	if (!map->hva)
 		return;
 
-	if (map->page != KVM_UNMAPPED_PAGE)
-		kunmap(map->page);
+	if (map->page != KVM_UNMAPPED_PAGE) {
+		if (atomic)
+			kunmap_atomic(map->hva);
+		else
+			kunmap(map->page);
+	}
 #ifdef CONFIG_HAS_IOMEM
-	else
+	else if (!atomic)
 		memunmap(map->hva);
+	else
+		WARN_ONCE(1, "Unexpected unmapping in atomic context");
 #endif
 
-	if (dirty) {
-		kvm_vcpu_mark_page_dirty(vcpu, map->gfn);
-		kvm_release_pfn_dirty(map->pfn);
-	} else {
-		kvm_release_pfn_clean(map->pfn);
-	}
+	if (dirty)
+		mark_page_dirty_in_slot(memslot, map->gfn);
+
+	if (cache)
+		cache->dirty |= dirty;
+	else
+		kvm_release_pfn(map->pfn, dirty, NULL);
 
 	map->hva = NULL;
 	map->page = NULL;
 }
+
+int kvm_unmap_gfn(struct kvm_vcpu *vcpu, struct kvm_host_map *map, 
+		  struct gfn_to_pfn_cache *cache, bool dirty, bool atomic)
+{
+	__kvm_unmap_gfn(gfn_to_memslot(vcpu->kvm, map->gfn), map,
+			cache, dirty, atomic);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_unmap_gfn);
+
+void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map, bool dirty)
+{
+	__kvm_unmap_gfn(kvm_vcpu_gfn_to_memslot(vcpu, map->gfn), map, NULL,
+			dirty, false);
+}
 EXPORT_SYMBOL_GPL(kvm_vcpu_unmap);
 
 struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn)
@@ -1931,11 +2007,8 @@ EXPORT_SYMBOL_GPL(kvm_release_pfn_dirty);
 
 void kvm_set_pfn_dirty(kvm_pfn_t pfn)
 {
-	if (!kvm_is_reserved_pfn(pfn) && !kvm_is_zone_device_pfn(pfn)) {
-		struct page *page = pfn_to_page(pfn);
-
-		SetPageDirty(page);
-	}
+	if (!kvm_is_reserved_pfn(pfn) && !kvm_is_zone_device_pfn(pfn))
+		SetPageDirty(pfn_to_page(pfn));
 }
 EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
 
@@ -2051,17 +2124,6 @@ static int __kvm_read_guest_atomic(struct kvm_memory_slot *slot, gfn_t gfn,
 	return 0;
 }
 
-int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
-			  unsigned long len)
-{
-	gfn_t gfn = gpa >> PAGE_SHIFT;
-	struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
-	int offset = offset_in_page(gpa);
-
-	return __kvm_read_guest_atomic(slot, gfn, data, offset, len);
-}
-EXPORT_SYMBOL_GPL(kvm_read_guest_atomic);
-
 int kvm_vcpu_read_guest_atomic(struct kvm_vcpu *vcpu, gpa_t gpa,
 			       void *data, unsigned long len)
 {
@@ -2158,33 +2220,36 @@ static int __kvm_gfn_to_hva_cache_init(struct kvm_memslots *slots,
 	gfn_t end_gfn = (gpa + len - 1) >> PAGE_SHIFT;
 	gfn_t nr_pages_needed = end_gfn - start_gfn + 1;
 	gfn_t nr_pages_avail;
-	int r = start_gfn <= end_gfn ? 0 : -EINVAL;
 
-	ghc->gpa = gpa;
+	/* Update ghc->generation before performing any error checks. */
 	ghc->generation = slots->generation;
-	ghc->len = len;
-	ghc->hva = KVM_HVA_ERR_BAD;
+
+	if (start_gfn > end_gfn) {
+		ghc->hva = KVM_HVA_ERR_BAD;
+		return -EINVAL;
+	}
 
 	/*
 	 * If the requested region crosses two memslots, we still
 	 * verify that the entire region is valid here.
 	 */
-	while (!r && start_gfn <= end_gfn) {
+	for ( ; start_gfn <= end_gfn; start_gfn += nr_pages_avail) {
 		ghc->memslot = __gfn_to_memslot(slots, start_gfn);
 		ghc->hva = gfn_to_hva_many(ghc->memslot, start_gfn,
 					   &nr_pages_avail);
 		if (kvm_is_error_hva(ghc->hva))
-			r = -EFAULT;
-		start_gfn += nr_pages_avail;
+			return -EFAULT;
 	}
 
 	/* Use the slow path for cross page reads and writes. */
-	if (!r && nr_pages_needed == 1)
+	if (nr_pages_needed == 1)
 		ghc->hva += offset;
 	else
 		ghc->memslot = NULL;
 
-	return r;
+	ghc->gpa = gpa;
+	ghc->len = len;
+	return 0;
 }
 
 int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
@@ -2205,15 +2270,17 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 
 	BUG_ON(len + offset > ghc->len);
 
-	if (slots->generation != ghc->generation)
-		__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len);
-
-	if (unlikely(!ghc->memslot))
-		return kvm_write_guest(kvm, gpa, data, len);
+	if (slots->generation != ghc->generation) {
+		if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
+			return -EFAULT;
+	}
 
 	if (kvm_is_error_hva(ghc->hva))
 		return -EFAULT;
 
+	if (unlikely(!ghc->memslot))
+		return kvm_write_guest(kvm, gpa, data, len);
+
 	r = __copy_to_user((void __user *)ghc->hva + offset, data, len);
 	if (r)
 		return -EFAULT;
@@ -2238,15 +2305,17 @@ int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 
 	BUG_ON(len > ghc->len);
 
-	if (slots->generation != ghc->generation)
-		__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len);
-
-	if (unlikely(!ghc->memslot))
-		return kvm_read_guest(kvm, ghc->gpa, data, len);
+	if (slots->generation != ghc->generation) {
+		if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
+			return -EFAULT;
+	}
 
 	if (kvm_is_error_hva(ghc->hva))
 		return -EFAULT;
 
+	if (unlikely(!ghc->memslot))
+		return kvm_read_guest(kvm, ghc->gpa, data, len);
+
 	r = __copy_from_user(data, (void __user *)ghc->hva, len);
 	if (r)
 		return -EFAULT;
@@ -2718,6 +2787,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 {
 	int r;
 	struct kvm_vcpu *vcpu;
+	struct page *page;
 
 	if (id >= KVM_MAX_VCPU_ID)
 		return -EINVAL;
@@ -2731,17 +2801,29 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 	kvm->created_vcpus++;
 	mutex_unlock(&kvm->lock);
 
-	vcpu = kvm_arch_vcpu_create(kvm, id);
-	if (IS_ERR(vcpu)) {
-		r = PTR_ERR(vcpu);
+	r = kvm_arch_vcpu_precreate(kvm, id);
+	if (r)
+		goto vcpu_decrement;
+
+	vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
+	if (!vcpu) {
+		r = -ENOMEM;
 		goto vcpu_decrement;
 	}
 
-	preempt_notifier_init(&vcpu->preempt_notifier, &kvm_preempt_ops);
+	BUILD_BUG_ON(sizeof(struct kvm_run) > PAGE_SIZE);
+	page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+	if (!page) {
+		r = -ENOMEM;
+		goto vcpu_free;
+	}
+	vcpu->run = page_address(page);
+
+	kvm_vcpu_init(vcpu, kvm, id);
 
-	r = kvm_arch_vcpu_setup(vcpu);
+	r = kvm_arch_vcpu_create(vcpu);
 	if (r)
-		goto vcpu_destroy;
+		goto vcpu_free_run_page;
 
 	kvm_create_vcpu_debugfs(vcpu);
 
@@ -2778,8 +2860,11 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
 unlock_vcpu_destroy:
 	mutex_unlock(&kvm->lock);
 	debugfs_remove_recursive(vcpu->debugfs_dentry);
-vcpu_destroy:
 	kvm_arch_vcpu_destroy(vcpu);
+vcpu_free_run_page:
+	free_page((unsigned long)vcpu->run);
+vcpu_free:
+	kmem_cache_free(kvm_vcpu_cache, vcpu);
 vcpu_decrement:
 	mutex_lock(&kvm->lock);
 	kvm->created_vcpus--;
@@ -4013,8 +4098,9 @@ static int kvm_debugfs_open(struct inode *inode, struct file *file,
 		return -ENOENT;
 
 	if (simple_attr_open(inode, file, get,
-			     stat_data->mode & S_IWUGO ? set : NULL,
-			     fmt)) {
+		    KVM_DBGFS_GET_MODE(stat_data->dbgfs_item) & 0222
+		    ? set : NULL,
+		    fmt)) {
 		kvm_put_kvm(stat_data->kvm);
 		return -ENOMEM;
 	}
@@ -4033,105 +4119,111 @@ static int kvm_debugfs_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static int vm_stat_get_per_vm(void *data, u64 *val)
+static int kvm_get_stat_per_vm(struct kvm *kvm, size_t offset, u64 *val)
 {
-	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
+	*val = *(ulong *)((void *)kvm + offset);
+
+	return 0;
+}
 
-	*val = *(ulong *)((void *)stat_data->kvm + stat_data->offset);
+static int kvm_clear_stat_per_vm(struct kvm *kvm, size_t offset)
+{
+	*(ulong *)((void *)kvm + offset) = 0;
 
 	return 0;
 }
 
-static int vm_stat_clear_per_vm(void *data, u64 val)
+static int kvm_get_stat_per_vcpu(struct kvm *kvm, size_t offset, u64 *val)
 {
-	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
+	int i;
+	struct kvm_vcpu *vcpu;
 
-	if (val)
-		return -EINVAL;
+	*val = 0;
 
-	*(ulong *)((void *)stat_data->kvm + stat_data->offset) = 0;
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		*val += *(u64 *)((void *)vcpu + offset);
 
 	return 0;
 }
 
-static int vm_stat_get_per_vm_open(struct inode *inode, struct file *file)
+static int kvm_clear_stat_per_vcpu(struct kvm *kvm, size_t offset)
 {
-	__simple_attr_check_format("%llu\n", 0ull);
-	return kvm_debugfs_open(inode, file, vm_stat_get_per_vm,
-				vm_stat_clear_per_vm, "%llu\n");
-}
+	int i;
+	struct kvm_vcpu *vcpu;
 
-static const struct file_operations vm_stat_get_per_vm_fops = {
-	.owner   = THIS_MODULE,
-	.open    = vm_stat_get_per_vm_open,
-	.release = kvm_debugfs_release,
-	.read    = simple_attr_read,
-	.write   = simple_attr_write,
-	.llseek  = no_llseek,
-};
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		*(u64 *)((void *)vcpu + offset) = 0;
+
+	return 0;
+}
 
-static int vcpu_stat_get_per_vm(void *data, u64 *val)
+static int kvm_stat_data_get(void *data, u64 *val)
 {
-	int i;
+	int r = -EFAULT;
 	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
-	struct kvm_vcpu *vcpu;
-
-	*val = 0;
 
-	kvm_for_each_vcpu(i, vcpu, stat_data->kvm)
-		*val += *(u64 *)((void *)vcpu + stat_data->offset);
+	switch (stat_data->dbgfs_item->kind) {
+	case KVM_STAT_VM:
+		r = kvm_get_stat_per_vm(stat_data->kvm,
+					stat_data->dbgfs_item->offset, val);
+		break;
+	case KVM_STAT_VCPU:
+		r = kvm_get_stat_per_vcpu(stat_data->kvm,
+					  stat_data->dbgfs_item->offset, val);
+		break;
+	}
 
-	return 0;
+	return r;
 }
 
-static int vcpu_stat_clear_per_vm(void *data, u64 val)
+static int kvm_stat_data_clear(void *data, u64 val)
 {
-	int i;
+	int r = -EFAULT;
 	struct kvm_stat_data *stat_data = (struct kvm_stat_data *)data;
-	struct kvm_vcpu *vcpu;
 
 	if (val)
 		return -EINVAL;
 
-	kvm_for_each_vcpu(i, vcpu, stat_data->kvm)
-		*(u64 *)((void *)vcpu + stat_data->offset) = 0;
+	switch (stat_data->dbgfs_item->kind) {
+	case KVM_STAT_VM:
+		r = kvm_clear_stat_per_vm(stat_data->kvm,
+					  stat_data->dbgfs_item->offset);
+		break;
+	case KVM_STAT_VCPU:
+		r = kvm_clear_stat_per_vcpu(stat_data->kvm,
+					    stat_data->dbgfs_item->offset);
+		break;
+	}
 
-	return 0;
+	return r;
 }
 
-static int vcpu_stat_get_per_vm_open(struct inode *inode, struct file *file)
+static int kvm_stat_data_open(struct inode *inode, struct file *file)
 {
 	__simple_attr_check_format("%llu\n", 0ull);
-	return kvm_debugfs_open(inode, file, vcpu_stat_get_per_vm,
-				 vcpu_stat_clear_per_vm, "%llu\n");
+	return kvm_debugfs_open(inode, file, kvm_stat_data_get,
+				kvm_stat_data_clear, "%llu\n");
 }
 
-static const struct file_operations vcpu_stat_get_per_vm_fops = {
-	.owner   = THIS_MODULE,
-	.open    = vcpu_stat_get_per_vm_open,
+static const struct file_operations stat_fops_per_vm = {
+	.owner = THIS_MODULE,
+	.open = kvm_stat_data_open,
 	.release = kvm_debugfs_release,
-	.read    = simple_attr_read,
-	.write   = simple_attr_write,
-	.llseek  = no_llseek,
-};
-
-static const struct file_operations *stat_fops_per_vm[] = {
-	[KVM_STAT_VCPU] = &vcpu_stat_get_per_vm_fops,
-	[KVM_STAT_VM]   = &vm_stat_get_per_vm_fops,
+	.read = simple_attr_read,
+	.write = simple_attr_write,
+	.llseek = no_llseek,
 };
 
 static int vm_stat_get(void *_offset, u64 *val)
 {
 	unsigned offset = (long)_offset;
 	struct kvm *kvm;
-	struct kvm_stat_data stat_tmp = {.offset = offset};
 	u64 tmp_val;
 
 	*val = 0;
 	mutex_lock(&kvm_lock);
 	list_for_each_entry(kvm, &vm_list, vm_list) {
-		stat_tmp.kvm = kvm;
-		vm_stat_get_per_vm((void *)&stat_tmp, &tmp_val);
+		kvm_get_stat_per_vm(kvm, offset, &tmp_val);
 		*val += tmp_val;
 	}
 	mutex_unlock(&kvm_lock);
@@ -4142,15 +4234,13 @@ static int vm_stat_clear(void *_offset, u64 val)
 {
 	unsigned offset = (long)_offset;
 	struct kvm *kvm;
-	struct kvm_stat_data stat_tmp = {.offset = offset};
 
 	if (val)
 		return -EINVAL;
 
 	mutex_lock(&kvm_lock);
 	list_for_each_entry(kvm, &vm_list, vm_list) {
-		stat_tmp.kvm = kvm;
-		vm_stat_clear_per_vm((void *)&stat_tmp, 0);
+		kvm_clear_stat_per_vm(kvm, offset);
 	}
 	mutex_unlock(&kvm_lock);
 
@@ -4163,14 +4253,12 @@ static int vcpu_stat_get(void *_offset, u64 *val)
 {
 	unsigned offset = (long)_offset;
 	struct kvm *kvm;
-	struct kvm_stat_data stat_tmp = {.offset = offset};
 	u64 tmp_val;
 
 	*val = 0;
 	mutex_lock(&kvm_lock);
 	list_for_each_entry(kvm, &vm_list, vm_list) {
-		stat_tmp.kvm = kvm;
-		vcpu_stat_get_per_vm((void *)&stat_tmp, &tmp_val);
+		kvm_get_stat_per_vcpu(kvm, offset, &tmp_val);
 		*val += tmp_val;
 	}
 	mutex_unlock(&kvm_lock);
@@ -4181,15 +4269,13 @@ static int vcpu_stat_clear(void *_offset, u64 val)
 {
 	unsigned offset = (long)_offset;
 	struct kvm *kvm;
-	struct kvm_stat_data stat_tmp = {.offset = offset};
 
 	if (val)
 		return -EINVAL;
 
 	mutex_lock(&kvm_lock);
 	list_for_each_entry(kvm, &vm_list, vm_list) {
-		stat_tmp.kvm = kvm;
-		vcpu_stat_clear_per_vm((void *)&stat_tmp, 0);
+		kvm_clear_stat_per_vcpu(kvm, offset);
 	}
 	mutex_unlock(&kvm_lock);
 
@@ -4262,9 +4348,8 @@ static void kvm_init_debug(void)
 
 	kvm_debugfs_num_entries = 0;
 	for (p = debugfs_entries; p->name; ++p, kvm_debugfs_num_entries++) {
-		int mode = p->mode ? p->mode : 0644;
-		debugfs_create_file(p->name, mode, kvm_debugfs_dir,
-				    (void *)(long)p->offset,
+		debugfs_create_file(p->name, KVM_DBGFS_GET_MODE(p),
+				    kvm_debugfs_dir, (void *)(long)p->offset,
 				    stat_fops[p->kind]);
 	}
 }
@@ -4304,8 +4389,8 @@ static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
 	WRITE_ONCE(vcpu->preempted, false);
 	WRITE_ONCE(vcpu->ready, false);
 
+	__this_cpu_write(kvm_running_vcpu, vcpu);
 	kvm_arch_sched_in(vcpu, cpu);
-
 	kvm_arch_vcpu_load(vcpu, cpu);
 }
 
@@ -4319,6 +4404,25 @@ static void kvm_sched_out(struct preempt_notifier *pn,
 		WRITE_ONCE(vcpu->ready, true);
 	}
 	kvm_arch_vcpu_put(vcpu);
+	__this_cpu_write(kvm_running_vcpu, NULL);
+}
+
+/**
+ * kvm_get_running_vcpu - get the vcpu running on the current CPU.
+ * Thanks to preempt notifiers, this can also be called from
+ * preemptible context.
+ */
+struct kvm_vcpu *kvm_get_running_vcpu(void)
+{
+        return __this_cpu_read(kvm_running_vcpu);
+}
+
+/**
+ * kvm_get_running_vcpus - get the per-CPU array of currently running vcpus.
+ */
+struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void)
+{
+        return &kvm_running_vcpu;
 }
 
 static void check_processor_compat(void *rtn)