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Sun, 2 Mar 2025 14:34:08 +0000 (UTC) Received: from server.redhat.com (unknown [10.72.112.49]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id B9747195395A; Sun, 2 Mar 2025 14:34:03 +0000 (UTC) From: Cindy Lu To: lulu@redhat.com, jasowang@redhat.com, mst@redhat.com, michael.christie@oracle.com, sgarzare@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org Subject: [PATCH v7 6/8] vhost: uapi to control task mode (owner vs kthread) Date: Sun, 2 Mar 2025 22:32:08 +0800 Message-ID: <20250302143259.1221569-7-lulu@redhat.com> In-Reply-To: <20250302143259.1221569-1-lulu@redhat.com> References: <20250302143259.1221569-1-lulu@redhat.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 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 --- 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