diff mbox series

[v9,8/8] KVM: Enable and expose KVM_MEM_PRIVATE

Message ID 20221025151344.3784230-9-chao.p.peng@linux.intel.com (mailing list archive)
State New
Headers show
Series KVM: mm: fd-based approach for supporting KVM | expand

Commit Message

Chao Peng Oct. 25, 2022, 3:13 p.m. UTC
Expose KVM_MEM_PRIVATE and memslot fields restricted_fd/offset to
userspace. KVM register/unregister private memslot to fd-based
memory backing store and responses to invalidation event from
restrictedmem_notifier to zap the existing memory mappings in the
secondary page table.

Whether KVM_MEM_PRIVATE is actually exposed to userspace is determined
by architecture code which can turn on it by overriding the default
kvm_arch_has_private_mem().

A 'kvm' reference is added in memslot structure since in
restrictedmem_notifier callback we can only obtain a memslot reference
but 'kvm' is needed to do the zapping.

Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 include/linux/kvm_host.h |   3 +-
 virt/kvm/kvm_main.c      | 174 +++++++++++++++++++++++++++++++++++++--
 2 files changed, 171 insertions(+), 6 deletions(-)

Comments

Fuad Tabba Oct. 27, 2022, 10:31 a.m. UTC | #1
Hi,

On Tue, Oct 25, 2022 at 4:20 PM Chao Peng <chao.p.peng@linux.intel.com> wrote:
>
> Expose KVM_MEM_PRIVATE and memslot fields restricted_fd/offset to
> userspace. KVM register/unregister private memslot to fd-based
> memory backing store and responses to invalidation event from
> restrictedmem_notifier to zap the existing memory mappings in the
> secondary page table.
>
> Whether KVM_MEM_PRIVATE is actually exposed to userspace is determined
> by architecture code which can turn on it by overriding the default
> kvm_arch_has_private_mem().
>
> A 'kvm' reference is added in memslot structure since in
> restrictedmem_notifier callback we can only obtain a memslot reference
> but 'kvm' is needed to do the zapping.
>
> Co-developed-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
>  include/linux/kvm_host.h |   3 +-
>  virt/kvm/kvm_main.c      | 174 +++++++++++++++++++++++++++++++++++++--
>  2 files changed, 171 insertions(+), 6 deletions(-)

Reviewed-by: Fuad Tabba <tabba@google.com>

Thanks,
/fuad


>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 69300fc6d572..e27d62c30484 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -246,7 +246,7 @@ int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
>  #endif
>
>
> -#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_KVM_GENERIC_PRIVATE_MEM)
> +#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_HAVE_KVM_RESTRICTED_MEM)
>  struct kvm_gfn_range {
>         struct kvm_memory_slot *slot;
>         gfn_t start;
> @@ -583,6 +583,7 @@ struct kvm_memory_slot {
>         struct file *restricted_file;
>         loff_t restricted_offset;
>         struct restrictedmem_notifier notifier;
> +       struct kvm *kvm;
>  };
>
>  static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot)
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 13a37b4d9e97..dae6a2c196ad 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1028,6 +1028,111 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size,
>  }
>  #endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */
>
> +#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM
> +static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot,
> +                                        pgoff_t start, pgoff_t end,
> +                                        gfn_t *gfn_start, gfn_t *gfn_end)
> +{
> +       unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT;
> +
> +       if (start > base_pgoff)
> +               *gfn_start = slot->base_gfn + start - base_pgoff;
> +       else
> +               *gfn_start = slot->base_gfn;
> +
> +       if (end < base_pgoff + slot->npages)
> +               *gfn_end = slot->base_gfn + end - base_pgoff;
> +       else
> +               *gfn_end = slot->base_gfn + slot->npages;
> +
> +       if (*gfn_start >= *gfn_end)
> +               return false;
> +
> +       return true;
> +}
> +
> +static void kvm_restrictedmem_invalidate_begin(struct restrictedmem_notifier *notifier,
> +                                              pgoff_t start, pgoff_t end)
> +{
> +       struct kvm_memory_slot *slot = container_of(notifier,
> +                                                   struct kvm_memory_slot,
> +                                                   notifier);
> +       struct kvm *kvm = slot->kvm;
> +       gfn_t gfn_start, gfn_end;
> +       struct kvm_gfn_range gfn_range;
> +       int idx;
> +
> +       if (!restrictedmem_range_is_valid(slot, start, end,
> +                                               &gfn_start, &gfn_end))
> +               return;
> +
> +       idx = srcu_read_lock(&kvm->srcu);
> +       KVM_MMU_LOCK(kvm);
> +
> +       kvm_mmu_invalidate_begin(kvm, gfn_start, gfn_end);
> +
> +       gfn_range.start = gfn_start;
> +       gfn_range.end = gfn_end;
> +       gfn_range.slot = slot;
> +       gfn_range.pte = __pte(0);
> +       gfn_range.may_block = true;
> +
> +       if (kvm_unmap_gfn_range(kvm, &gfn_range))
> +               kvm_flush_remote_tlbs(kvm);
> +
> +       KVM_MMU_UNLOCK(kvm);
> +       srcu_read_unlock(&kvm->srcu, idx);
> +}
> +
> +static void kvm_restrictedmem_invalidate_end(struct restrictedmem_notifier *notifier,
> +                                            pgoff_t start, pgoff_t end)
> +{
> +       struct kvm_memory_slot *slot = container_of(notifier,
> +                                                   struct kvm_memory_slot,
> +                                                   notifier);
> +       struct kvm *kvm = slot->kvm;
> +       gfn_t gfn_start, gfn_end;
> +
> +       if (!restrictedmem_range_is_valid(slot, start, end,
> +                                               &gfn_start, &gfn_end))
> +               return;
> +
> +       KVM_MMU_LOCK(kvm);
> +       kvm_mmu_invalidate_end(kvm, gfn_start, gfn_end);
> +       KVM_MMU_UNLOCK(kvm);
> +}
> +
> +static struct restrictedmem_notifier_ops kvm_restrictedmem_notifier_ops = {
> +       .invalidate_start = kvm_restrictedmem_invalidate_begin,
> +       .invalidate_end = kvm_restrictedmem_invalidate_end,
> +};
> +
> +static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot)
> +{
> +       slot->notifier.ops = &kvm_restrictedmem_notifier_ops;
> +       restrictedmem_register_notifier(slot->restricted_file, &slot->notifier);
> +}
> +
> +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot)
> +{
> +       restrictedmem_unregister_notifier(slot->restricted_file,
> +                                         &slot->notifier);
> +}
> +
> +#else /* !CONFIG_HAVE_KVM_RESTRICTED_MEM */
> +
> +static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot)
> +{
> +       WARN_ON_ONCE(1);
> +}
> +
> +static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot)
> +{
> +       WARN_ON_ONCE(1);
> +}
> +
> +#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */
> +
>  #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
>  static int kvm_pm_notifier_call(struct notifier_block *bl,
>                                 unsigned long state,
> @@ -1072,6 +1177,11 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
>  /* This does not remove the slot from struct kvm_memslots data structures */
>  static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
>  {
> +       if (slot->flags & KVM_MEM_PRIVATE) {
> +               kvm_restrictedmem_unregister(slot);
> +               fput(slot->restricted_file);
> +       }
> +
>         kvm_destroy_dirty_bitmap(slot);
>
>         kvm_arch_free_memslot(kvm, slot);
> @@ -1643,10 +1753,16 @@ bool __weak kvm_arch_has_private_mem(struct kvm *kvm)
>         return false;
>  }
>
> -static int check_memory_region_flags(const struct kvm_user_mem_region *mem)
> +static int check_memory_region_flags(struct kvm *kvm,
> +                                    const struct kvm_user_mem_region *mem)
>  {
>         u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
>
> +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM
> +       if (kvm_arch_has_private_mem(kvm))
> +               valid_flags |= KVM_MEM_PRIVATE;
> +#endif
> +
>  #ifdef __KVM_HAVE_READONLY_MEM
>         valid_flags |= KVM_MEM_READONLY;
>  #endif
> @@ -1722,6 +1838,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm,
>  {
>         int r;
>
> +       if (change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE)
> +               kvm_restrictedmem_register(new);
> +
>         /*
>          * If dirty logging is disabled, nullify the bitmap; the old bitmap
>          * will be freed on "commit".  If logging is enabled in both old and
> @@ -1750,6 +1869,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm,
>         if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap))
>                 kvm_destroy_dirty_bitmap(new);
>
> +       if (r && change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE)
> +               kvm_restrictedmem_unregister(new);
> +
>         return r;
>  }
>
> @@ -2047,7 +2169,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
>         int as_id, id;
>         int r;
>
> -       r = check_memory_region_flags(mem);
> +       r = check_memory_region_flags(kvm, mem);
>         if (r)
>                 return r;
>
> @@ -2066,6 +2188,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
>              !access_ok((void __user *)(unsigned long)mem->userspace_addr,
>                         mem->memory_size))
>                 return -EINVAL;
> +       if (mem->flags & KVM_MEM_PRIVATE &&
> +               (mem->restricted_offset & (PAGE_SIZE - 1) ||
> +                mem->restricted_offset > U64_MAX - mem->memory_size))
> +               return -EINVAL;
>         if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
>                 return -EINVAL;
>         if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
> @@ -2104,6 +2230,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
>                 if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
>                         return -EINVAL;
>         } else { /* Modify an existing slot. */
> +               /* Private memslots are immutable, they can only be deleted. */
> +               if (mem->flags & KVM_MEM_PRIVATE)
> +                       return -EINVAL;
>                 if ((mem->userspace_addr != old->userspace_addr) ||
>                     (npages != old->npages) ||
>                     ((mem->flags ^ old->flags) & KVM_MEM_READONLY))
> @@ -2132,10 +2261,28 @@ int __kvm_set_memory_region(struct kvm *kvm,
>         new->npages = npages;
>         new->flags = mem->flags;
>         new->userspace_addr = mem->userspace_addr;
> +       if (mem->flags & KVM_MEM_PRIVATE) {
> +               new->restricted_file = fget(mem->restricted_fd);
> +               if (!new->restricted_file ||
> +                   !file_is_restrictedmem(new->restricted_file)) {
> +                       r = -EINVAL;
> +                       goto out;
> +               }
> +               new->restricted_offset = mem->restricted_offset;
> +       }
> +
> +       new->kvm = kvm;
>
>         r = kvm_set_memslot(kvm, old, new, change);
>         if (r)
> -               kfree(new);
> +               goto out;
> +
> +       return 0;
> +
> +out:
> +       if (new->restricted_file)
> +               fput(new->restricted_file);
> +       kfree(new);
>         return r;
>  }
>  EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
> @@ -4604,6 +4751,11 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
>         case KVM_CAP_BINARY_STATS_FD:
>         case KVM_CAP_SYSTEM_EVENT_DATA:
>                 return 1;
> +#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM
> +       case KVM_CAP_PRIVATE_MEM:
> +               return 1;
> +#endif
> +
>         default:
>                 break;
>         }
> @@ -4795,16 +4947,28 @@ static long kvm_vm_ioctl(struct file *filp,
>         }
>         case KVM_SET_USER_MEMORY_REGION: {
>                 struct kvm_user_mem_region mem;
> -               unsigned long size = sizeof(struct kvm_userspace_memory_region);
> +               unsigned int flags_offset = offsetof(typeof(mem), flags);
> +               unsigned long size;
> +               u32 flags;
>
>                 kvm_sanity_check_user_mem_region_alias();
>
> +               memset(&mem, 0, sizeof(mem));
> +
>                 r = -EFAULT;
> +               if (get_user(flags, (u32 __user *)(argp + flags_offset)))
> +                       goto out;
> +
> +               if (flags & KVM_MEM_PRIVATE)
> +                       size = sizeof(struct kvm_userspace_memory_region_ext);
> +               else
> +                       size = sizeof(struct kvm_userspace_memory_region);
> +
>                 if (copy_from_user(&mem, argp, size))
>                         goto out;
>
>                 r = -EINVAL;
> -               if (mem.flags & KVM_MEM_PRIVATE)
> +               if ((flags ^ mem.flags) & KVM_MEM_PRIVATE)
>                         goto out;
>
>                 r = kvm_vm_ioctl_set_memory_region(kvm, &mem);
> --
> 2.25.1
>
diff mbox series

Patch

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 69300fc6d572..e27d62c30484 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -246,7 +246,7 @@  int kvm_async_pf_wakeup_all(struct kvm_vcpu *vcpu);
 #endif
 
 
-#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_KVM_GENERIC_PRIVATE_MEM)
+#if defined(KVM_ARCH_WANT_MMU_NOTIFIER) || defined(CONFIG_HAVE_KVM_RESTRICTED_MEM)
 struct kvm_gfn_range {
 	struct kvm_memory_slot *slot;
 	gfn_t start;
@@ -583,6 +583,7 @@  struct kvm_memory_slot {
 	struct file *restricted_file;
 	loff_t restricted_offset;
 	struct restrictedmem_notifier notifier;
+	struct kvm *kvm;
 };
 
 static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 13a37b4d9e97..dae6a2c196ad 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1028,6 +1028,111 @@  static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size,
 }
 #endif /* CONFIG_KVM_GENERIC_PRIVATE_MEM */
 
+#ifdef CONFIG_HAVE_KVM_RESTRICTED_MEM
+static bool restrictedmem_range_is_valid(struct kvm_memory_slot *slot,
+					 pgoff_t start, pgoff_t end,
+					 gfn_t *gfn_start, gfn_t *gfn_end)
+{
+	unsigned long base_pgoff = slot->restricted_offset >> PAGE_SHIFT;
+
+	if (start > base_pgoff)
+		*gfn_start = slot->base_gfn + start - base_pgoff;
+	else
+		*gfn_start = slot->base_gfn;
+
+	if (end < base_pgoff + slot->npages)
+		*gfn_end = slot->base_gfn + end - base_pgoff;
+	else
+		*gfn_end = slot->base_gfn + slot->npages;
+
+	if (*gfn_start >= *gfn_end)
+		return false;
+
+	return true;
+}
+
+static void kvm_restrictedmem_invalidate_begin(struct restrictedmem_notifier *notifier,
+					       pgoff_t start, pgoff_t end)
+{
+	struct kvm_memory_slot *slot = container_of(notifier,
+						    struct kvm_memory_slot,
+						    notifier);
+	struct kvm *kvm = slot->kvm;
+	gfn_t gfn_start, gfn_end;
+	struct kvm_gfn_range gfn_range;
+	int idx;
+
+	if (!restrictedmem_range_is_valid(slot, start, end,
+						&gfn_start, &gfn_end))
+		return;
+
+	idx = srcu_read_lock(&kvm->srcu);
+	KVM_MMU_LOCK(kvm);
+
+	kvm_mmu_invalidate_begin(kvm, gfn_start, gfn_end);
+
+	gfn_range.start = gfn_start;
+	gfn_range.end = gfn_end;
+	gfn_range.slot = slot;
+	gfn_range.pte = __pte(0);
+	gfn_range.may_block = true;
+
+	if (kvm_unmap_gfn_range(kvm, &gfn_range))
+		kvm_flush_remote_tlbs(kvm);
+
+	KVM_MMU_UNLOCK(kvm);
+	srcu_read_unlock(&kvm->srcu, idx);
+}
+
+static void kvm_restrictedmem_invalidate_end(struct restrictedmem_notifier *notifier,
+					     pgoff_t start, pgoff_t end)
+{
+	struct kvm_memory_slot *slot = container_of(notifier,
+						    struct kvm_memory_slot,
+						    notifier);
+	struct kvm *kvm = slot->kvm;
+	gfn_t gfn_start, gfn_end;
+
+	if (!restrictedmem_range_is_valid(slot, start, end,
+						&gfn_start, &gfn_end))
+		return;
+
+	KVM_MMU_LOCK(kvm);
+	kvm_mmu_invalidate_end(kvm, gfn_start, gfn_end);
+	KVM_MMU_UNLOCK(kvm);
+}
+
+static struct restrictedmem_notifier_ops kvm_restrictedmem_notifier_ops = {
+	.invalidate_start = kvm_restrictedmem_invalidate_begin,
+	.invalidate_end = kvm_restrictedmem_invalidate_end,
+};
+
+static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot)
+{
+	slot->notifier.ops = &kvm_restrictedmem_notifier_ops;
+	restrictedmem_register_notifier(slot->restricted_file, &slot->notifier);
+}
+
+static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot)
+{
+	restrictedmem_unregister_notifier(slot->restricted_file,
+					  &slot->notifier);
+}
+
+#else /* !CONFIG_HAVE_KVM_RESTRICTED_MEM */
+
+static inline void kvm_restrictedmem_register(struct kvm_memory_slot *slot)
+{
+	WARN_ON_ONCE(1);
+}
+
+static inline void kvm_restrictedmem_unregister(struct kvm_memory_slot *slot)
+{
+	WARN_ON_ONCE(1);
+}
+
+#endif /* CONFIG_HAVE_KVM_RESTRICTED_MEM */
+
 #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
 static int kvm_pm_notifier_call(struct notifier_block *bl,
 				unsigned long state,
@@ -1072,6 +1177,11 @@  static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
 /* This does not remove the slot from struct kvm_memslots data structures */
 static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
+	if (slot->flags & KVM_MEM_PRIVATE) {
+		kvm_restrictedmem_unregister(slot);
+		fput(slot->restricted_file);
+	}
+
 	kvm_destroy_dirty_bitmap(slot);
 
 	kvm_arch_free_memslot(kvm, slot);
@@ -1643,10 +1753,16 @@  bool __weak kvm_arch_has_private_mem(struct kvm *kvm)
 	return false;
 }
 
-static int check_memory_region_flags(const struct kvm_user_mem_region *mem)
+static int check_memory_region_flags(struct kvm *kvm,
+				     const struct kvm_user_mem_region *mem)
 {
 	u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
 
+#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM
+	if (kvm_arch_has_private_mem(kvm))
+		valid_flags |= KVM_MEM_PRIVATE;
+#endif
+
 #ifdef __KVM_HAVE_READONLY_MEM
 	valid_flags |= KVM_MEM_READONLY;
 #endif
@@ -1722,6 +1838,9 @@  static int kvm_prepare_memory_region(struct kvm *kvm,
 {
 	int r;
 
+	if (change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE)
+		kvm_restrictedmem_register(new);
+
 	/*
 	 * If dirty logging is disabled, nullify the bitmap; the old bitmap
 	 * will be freed on "commit".  If logging is enabled in both old and
@@ -1750,6 +1869,9 @@  static int kvm_prepare_memory_region(struct kvm *kvm,
 	if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap))
 		kvm_destroy_dirty_bitmap(new);
 
+	if (r && change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE)
+		kvm_restrictedmem_unregister(new);
+
 	return r;
 }
 
@@ -2047,7 +2169,7 @@  int __kvm_set_memory_region(struct kvm *kvm,
 	int as_id, id;
 	int r;
 
-	r = check_memory_region_flags(mem);
+	r = check_memory_region_flags(kvm, mem);
 	if (r)
 		return r;
 
@@ -2066,6 +2188,10 @@  int __kvm_set_memory_region(struct kvm *kvm,
 	     !access_ok((void __user *)(unsigned long)mem->userspace_addr,
 			mem->memory_size))
 		return -EINVAL;
+	if (mem->flags & KVM_MEM_PRIVATE &&
+		(mem->restricted_offset & (PAGE_SIZE - 1) ||
+		 mem->restricted_offset > U64_MAX - mem->memory_size))
+		return -EINVAL;
 	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
 		return -EINVAL;
 	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
@@ -2104,6 +2230,9 @@  int __kvm_set_memory_region(struct kvm *kvm,
 		if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
 			return -EINVAL;
 	} else { /* Modify an existing slot. */
+		/* Private memslots are immutable, they can only be deleted. */
+		if (mem->flags & KVM_MEM_PRIVATE)
+			return -EINVAL;
 		if ((mem->userspace_addr != old->userspace_addr) ||
 		    (npages != old->npages) ||
 		    ((mem->flags ^ old->flags) & KVM_MEM_READONLY))
@@ -2132,10 +2261,28 @@  int __kvm_set_memory_region(struct kvm *kvm,
 	new->npages = npages;
 	new->flags = mem->flags;
 	new->userspace_addr = mem->userspace_addr;
+	if (mem->flags & KVM_MEM_PRIVATE) {
+		new->restricted_file = fget(mem->restricted_fd);
+		if (!new->restricted_file ||
+		    !file_is_restrictedmem(new->restricted_file)) {
+			r = -EINVAL;
+			goto out;
+		}
+		new->restricted_offset = mem->restricted_offset;
+	}
+
+	new->kvm = kvm;
 
 	r = kvm_set_memslot(kvm, old, new, change);
 	if (r)
-		kfree(new);
+		goto out;
+
+	return 0;
+
+out:
+	if (new->restricted_file)
+		fput(new->restricted_file);
+	kfree(new);
 	return r;
 }
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
@@ -4604,6 +4751,11 @@  static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 	case KVM_CAP_BINARY_STATS_FD:
 	case KVM_CAP_SYSTEM_EVENT_DATA:
 		return 1;
+#ifdef CONFIG_KVM_GENERIC_PRIVATE_MEM
+	case KVM_CAP_PRIVATE_MEM:
+		return 1;
+#endif
+
 	default:
 		break;
 	}
@@ -4795,16 +4947,28 @@  static long kvm_vm_ioctl(struct file *filp,
 	}
 	case KVM_SET_USER_MEMORY_REGION: {
 		struct kvm_user_mem_region mem;
-		unsigned long size = sizeof(struct kvm_userspace_memory_region);
+		unsigned int flags_offset = offsetof(typeof(mem), flags);
+		unsigned long size;
+		u32 flags;
 
 		kvm_sanity_check_user_mem_region_alias();
 
+		memset(&mem, 0, sizeof(mem));
+
 		r = -EFAULT;
+		if (get_user(flags, (u32 __user *)(argp + flags_offset)))
+			goto out;
+
+		if (flags & KVM_MEM_PRIVATE)
+			size = sizeof(struct kvm_userspace_memory_region_ext);
+		else
+			size = sizeof(struct kvm_userspace_memory_region);
+
 		if (copy_from_user(&mem, argp, size))
 			goto out;
 
 		r = -EINVAL;
-		if (mem.flags & KVM_MEM_PRIVATE)
+		if ((flags ^ mem.flags) & KVM_MEM_PRIVATE)
 			goto out;
 
 		r = kvm_vm_ioctl_set_memory_region(kvm, &mem);