Add a new UAPI to enable setting the vhost device to task mode.
The userspace application can use VHOST_SET_INHERIT_FROM_OWNER
to configure the mode if necessary.
This setting must be applied before VHOST_SET_OWNER, as the worker
will be created in the VHOST_SET_OWNER function

Signed-off-by: Cindy Lu <redacted>
---
drivers/vhost/vhost.c      | 24 ++++++++++++++++++++++--
include/uapi/linux/vhost.h | 18 ++++++++++++++++++
2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index d8c0ea118bb1..45d8f5c5bca9 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c

@@ -1133,7 +1133,7 @@ void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_iotlb *umem)

	int i;

	vhost_dev_cleanup(dev);
-
+	dev->inherit_owner = true;
	dev->umem = umem;
	/* We don't need VQ locks below since vhost_dev_cleanup makes sure
	 * VQs aren't running.

@@ -2278,15 +2278,35 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)

{
	struct eventfd_ctx *ctx;
	u64 p;
-	long r;
+	long r = 0;
	int i, fd;
+	u8 inherit_owner;

	/* If you are not the owner, you can become one */
	if (ioctl == VHOST_SET_OWNER) {
		r = vhost_dev_set_owner(d);
		goto done;
	}
+	if (ioctl == VHOST_FORK_FROM_OWNER) {
+		/*inherit_owner can only be modified before owner is set*/
+		if (vhost_dev_has_owner(d)) {
+			r = -EBUSY;
+			goto done;
+		}
+		if (copy_from_user(&inherit_owner, argp, sizeof(u8))) {
+			r = -EFAULT;
+			goto done;
+		}
+		/* Validate the inherit_owner value, ensuring it is either 0 or 1 */
+		if (inherit_owner > 1) {
+			r = -EINVAL;
+			goto done;
+		}
+
+		d->inherit_owner = (bool)inherit_owner;

+		goto done;
+	}
	/* You must be the owner to do anything else */
	r = vhost_dev_check_owner(d);
	if (r)

diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index b95dd84eef2d..8f558b433536 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h

@@ -235,4 +235,22 @@
 */

#define VHOST_VDPA_GET_VRING_SIZE	_IOWR(VHOST_VIRTIO, 0x82,	\
					      struct vhost_vring_state)
+
+/**
+ * VHOST_FORK_FROM_OWNER - Set the inherit_owner flag for the vhost device
+ *
+ * @param inherit_owner: An 8-bit value that determines the vhost thread mode
+ *
+ * When inherit_owner is set to 1:
+ *   - The VHOST worker threads inherit its values/checks from
+ *     the thread that owns the VHOST device, The vhost threads will
+ *     be counted in the nproc rlimits.