netdev - [PATCH v7 6/8] vhost: uapi to control task mode (owner vs kthread)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250302143259.1221569-7-lulu@redhat.com>
Date: Sun,  2 Mar 2025 22:32:08 +0800
From: Cindy Lu <lulu@...hat.com>
To: lulu@...hat.com,
	jasowang@...hat.com,
	mst@...hat.com,
	michael.christie@...cle.com,
	sgarzare@...hat.com,
	linux-kernel@...r.kernel.org,
	virtualization@...ts.linux-foundation.org,
	netdev@...r.kernel.org
Subject: [PATCH v7 6/8] vhost: uapi to control task mode (owner vs kthread)

Add a new UAPI to configure the vhost device to use the kthread mode
The userspace application can use IOCTL VHOST_FORK_FROM_OWNER
to choose between owner and kthread 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 <lulu@...hat.com>
---
 drivers/vhost/vhost.c      | 22 ++++++++++++++++++++--
 include/uapi/linux/vhost.h | 15 +++++++++++++++
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index be97028a8baf..ff930c2e5b78 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1134,7 +1134,7 @@ 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.
@@ -2287,7 +2287,25 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
 		r = vhost_dev_set_owner(d);
 		goto done;
 	}
-
+	if (ioctl == VHOST_FORK_FROM_OWNER) {
+		u8 inherit_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;
+		}
+		if (inherit_owner > 1) {
+			r = -EINVAL;
+			goto done;
+		}
+		d->inherit_owner = (bool)inherit_owner;
+		r = 0;
+		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..547b4fa4c3bd 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -235,4 +235,19 @@
  */
 #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(default value):
+ *   - Vhost will create tasks similar to processes forked from the owner,
+ *     inheriting all of the owner's attributes..
+ *
+ * When inherit_owner is set to 0:
+ *   - Vhost will create tasks as kernel thread
+ */
+#define VHOST_FORK_FROM_OWNER _IOW(VHOST_VIRTIO, 0x83, __u8)
+
 #endif
-- 
2.45.0