diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index abd7c32126ce..c1fac1e9f820 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -1319,7 +1319,7 @@ yet and must be cleared on entry.
 :Capability: KVM_CAP_USER_MEMORY
 :Architectures: all
 :Type: vm ioctl
-:Parameters: struct kvm_userspace_memory_region (in)
+:Parameters: struct kvm_userspace_memory_region(_ext) (in)
 :Returns: 0 on success, -1 on error
 
 ::
@@ -1332,9 +1332,18 @@ yet and must be cleared on entry.
 	__u64 userspace_addr; /* start of the userspace allocated memory */
   };
 
+  struct kvm_userspace_memory_region_ext {
+	struct kvm_userspace_memory_region region;
+	__u64 private_offset;
+	__u32 private_fd;
+	__u32 pad1;
+	__u64 pad2[14];
+  };
+
   /* for kvm_memory_region::flags */
   #define KVM_MEM_LOG_DIRTY_PAGES	(1UL << 0)
   #define KVM_MEM_READONLY	(1UL << 1)
+  #define KVM_MEM_PRIVATE		(1UL << 2)
 
 This ioctl allows the user to create, modify or delete a guest physical
 memory slot.  Bits 0-15 of "slot" specify the slot id and this value
@@ -1365,12 +1374,27 @@ It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr
 be identical.  This allows large pages in the guest to be backed by large
 pages in the host.
 
-The flags field supports two flags: KVM_MEM_LOG_DIRTY_PAGES and
-KVM_MEM_READONLY.  The former can be set to instruct KVM to keep track of
-writes to memory within the slot.  See KVM_GET_DIRTY_LOG ioctl to know how to
-use it.  The latter can be set, if KVM_CAP_READONLY_MEM capability allows it,
-to make a new slot read-only.  In this case, writes to this memory will be
-posted to userspace as KVM_EXIT_MMIO exits.
+kvm_userspace_memory_region_ext includes all the kvm_userspace_memory_region
+fields. It also includes additional fields for some specific features. See
+below description of flags field for more information. It's recommended to use
+kvm_userspace_memory_region_ext in new userspace code.
+
+The flags field supports below flags:
+
+- KVM_MEM_LOG_DIRTY_PAGES can be set to instruct KVM to keep track of writes to
+  memory within the slot.  See KVM_GET_DIRTY_LOG ioctl to know how to use it.
+
+- KVM_MEM_READONLY can be set, if KVM_CAP_READONLY_MEM capability allows it, to
+  make a new slot read-only.  In this case, writes to this memory will be posted
+  to userspace as KVM_EXIT_MMIO exits.
+
+- KVM_MEM_PRIVATE can be set to indicate a new slot has private memory backed by
+  a file descirptor(fd) and the content of the private memory is invisible to
+  userspace. In this case, userspace should use private_fd/private_offset in
+  kvm_userspace_memory_region_ext to instruct KVM to provide private memory to
+  guest. Userspace should guarantee not to map the same pfn indicated by
+  private_fd/private_offset to different gfns with multiple memslots. Failed to
+  do this may result undefined behavior.
 
 When the KVM_CAP_SYNC_MMU capability is available, changes in the backing of
 the memory region are automatically reflected into the guest.  For example, an
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index e3cbd7706136..31db64ec0b33 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -48,6 +48,7 @@ config KVM
 	select SRCU
 	select INTERVAL_TREE
 	select HAVE_KVM_PM_NOTIFIER if PM
+	select HAVE_KVM_PRIVATE_MEM if X86_64
 	help
 	  Support hosting fully virtualized guest machines using hardware
 	  virtualization extensions.  You will need a fairly recent
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d7374d768296..081f62ccc9a1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12183,7 +12183,7 @@ void __user * __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa,
 	}
 
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
-		struct kvm_userspace_memory_region m;
+		struct kvm_user_mem_region m;
 
 		m.slot = id | (i << 16);
 		m.flags = 0;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f4519d3689e1..eac1787b899b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -44,6 +44,7 @@
 
 #include <asm/kvm_host.h>
 #include <linux/kvm_dirty_ring.h>
+#include <linux/memfd.h>
 
 #ifndef KVM_MAX_VCPU_IDS
 #define KVM_MAX_VCPU_IDS KVM_MAX_VCPUS
@@ -576,8 +577,16 @@ struct kvm_memory_slot {
 	u32 flags;
 	short id;
 	u16 as_id;
+	struct file *private_file;
+	loff_t private_offset;
+	struct inaccessible_notifier notifier;
 };
 
+static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot)
+{
+	return slot && (slot->flags & KVM_MEM_PRIVATE);
+}
+
 static inline bool kvm_slot_dirty_track_enabled(const struct kvm_memory_slot *slot)
 {
 	return slot->flags & KVM_MEM_LOG_DIRTY_PAGES;
@@ -1104,9 +1113,9 @@ enum kvm_mr_change {
 };
 
 int kvm_set_memory_region(struct kvm *kvm,
-			  const struct kvm_userspace_memory_region *mem);
+			  const struct kvm_user_mem_region *mem);
 int __kvm_set_memory_region(struct kvm *kvm,
-			    const struct kvm_userspace_memory_region *mem);
+			    const struct kvm_user_mem_region *mem);
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot);
 void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen);
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index eed0315a77a6..3ef462fb3b2a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -103,6 +103,33 @@ struct kvm_userspace_memory_region {
 	__u64 userspace_addr; /* start of the userspace allocated memory */
 };
 
+struct kvm_userspace_memory_region_ext {
+	struct kvm_userspace_memory_region region;
+	__u64 private_offset;
+	__u32 private_fd;
+	__u32 pad1;
+	__u64 pad2[14];
+};
+
+#ifdef __KERNEL__
+/*
+ * kvm_user_mem_region is a kernel-only alias of kvm_userspace_memory_region_ext
+ * that "unpacks" kvm_userspace_memory_region so that KVM can directly access
+ * all fields from the top-level "extended" region.
+ */
+struct kvm_user_mem_region {
+	__u32 slot;
+	__u32 flags;
+	__u64 guest_phys_addr;
+	__u64 memory_size;
+	__u64 userspace_addr;
+	__u64 private_offset;
+	__u32 private_fd;
+	__u32 pad1;
+	__u64 pad2[14];
+};
+#endif
+
 /*
  * The bit 0 ~ bit 15 of kvm_memory_region::flags are visible for userspace,
  * other bits are reserved for kvm internal use which are defined in
@@ -110,6 +137,7 @@ struct kvm_userspace_memory_region {
  */
 #define KVM_MEM_LOG_DIRTY_PAGES	(1UL << 0)
 #define KVM_MEM_READONLY	(1UL << 1)
+#define KVM_MEM_PRIVATE		(1UL << 2)
 
 /* for KVM_IRQ_LINE */
 struct kvm_irq_level {
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index a8c5c9f06b3c..ccaff13cc5b8 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -72,3 +72,6 @@ config KVM_XFER_TO_GUEST_WORK
 
 config HAVE_KVM_PM_NOTIFIER
        bool
+
+config HAVE_KVM_PRIVATE_MEM
+       bool
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 584a5bab3af3..12dc0dc57b06 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1526,7 +1526,7 @@ static void kvm_replace_memslot(struct kvm *kvm,
 	}
 }
 
-static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
+static int check_memory_region_flags(const struct kvm_user_mem_region *mem)
 {
 	u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
 
@@ -1920,7 +1920,7 @@ static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
  * Must be called holding kvm->slots_lock for write.
  */
 int __kvm_set_memory_region(struct kvm *kvm,
-			    const struct kvm_userspace_memory_region *mem)
+			    const struct kvm_user_mem_region *mem)
 {
 	struct kvm_memory_slot *old, *new;
 	struct kvm_memslots *slots;
@@ -2024,7 +2024,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
 
 int kvm_set_memory_region(struct kvm *kvm,
-			  const struct kvm_userspace_memory_region *mem)
+			  const struct kvm_user_mem_region *mem)
 {
 	int r;
 
@@ -2036,7 +2036,7 @@ int kvm_set_memory_region(struct kvm *kvm,
 EXPORT_SYMBOL_GPL(kvm_set_memory_region);
 
 static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
-					  struct kvm_userspace_memory_region *mem)
+					  struct kvm_user_mem_region *mem)
 {
 	if ((u16)mem->slot >= KVM_USER_MEM_SLOTS)
 		return -EINVAL;
@@ -4622,6 +4622,33 @@ static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm)
 	return fd;
 }
 
+#define SANITY_CHECK_MEM_REGION_FIELD(field)					\
+do {										\
+	BUILD_BUG_ON(offsetof(struct kvm_user_mem_region, field) !=		\
+		     offsetof(struct kvm_userspace_memory_region, field));	\
+	BUILD_BUG_ON(sizeof_field(struct kvm_user_mem_region, field) !=		\
+		     sizeof_field(struct kvm_userspace_memory_region, field));	\
+} while (0)
+
+#define SANITY_CHECK_MEM_REGION_EXT_FIELD(field)					\
+do {											\
+	BUILD_BUG_ON(offsetof(struct kvm_user_mem_region, field) !=			\
+		     offsetof(struct kvm_userspace_memory_region_ext, field));		\
+	BUILD_BUG_ON(sizeof_field(struct kvm_user_mem_region, field) !=			\
+		     sizeof_field(struct kvm_userspace_memory_region_ext, field));	\
+} while (0)
+
+static void kvm_sanity_check_user_mem_region_alias(void)
+{
+	SANITY_CHECK_MEM_REGION_FIELD(slot);
+	SANITY_CHECK_MEM_REGION_FIELD(flags);
+	SANITY_CHECK_MEM_REGION_FIELD(guest_phys_addr);
+	SANITY_CHECK_MEM_REGION_FIELD(memory_size);
+	SANITY_CHECK_MEM_REGION_FIELD(userspace_addr);
+	SANITY_CHECK_MEM_REGION_EXT_FIELD(private_offset);
+	SANITY_CHECK_MEM_REGION_EXT_FIELD(private_fd);
+}
+
 static long kvm_vm_ioctl(struct file *filp,
 			   unsigned int ioctl, unsigned long arg)
 {
@@ -4645,14 +4672,20 @@ static long kvm_vm_ioctl(struct file *filp,
 		break;
 	}
 	case KVM_SET_USER_MEMORY_REGION: {
-		struct kvm_userspace_memory_region kvm_userspace_mem;
+		struct kvm_user_mem_region mem;
+		unsigned long size = sizeof(struct kvm_userspace_memory_region);
+
+		kvm_sanity_check_user_mem_region_alias();
 
 		r = -EFAULT;
-		if (copy_from_user(&kvm_userspace_mem, argp,
-						sizeof(kvm_userspace_mem)))
+		if (copy_from_user(&mem, argp, size);
+			goto out;
+
+		r = -EINVAL;
+		if (mem.flags & KVM_MEM_PRIVATE)
 			goto out;
 
-		r = kvm_vm_ioctl_set_memory_region(kvm, &kvm_userspace_mem);
+		r = kvm_vm_ioctl_set_memory_region(kvm, &mem);
 		break;
 	}
 	case KVM_GET_DIRTY_LOG: {
