On Wed, Feb 26, 2025 at 5:05 PM Stefano Garzarella <sgarz...@redhat.com> wrote:
>
> On Sun, Feb 23, 2025 at 11:36:20PM +0800, Cindy Lu wrote:
> >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 <l...@redhat.com>
> >---
> > 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.
>
> Should we document that this (inherit_owner = 1) is the default, so if
> the user doesn't call VHOST_FORK_FROM_OWNER, this mode will be
> automatically selected?
>
> Thanks,
> Stefano
sure, I will add this
thanks
cindy
> >+ *
> >+ * When inherit_owner is set to 0:
> >+ * - The VHOST worker threads will use the traditional kernel thread
> >(kthread)
> >+ * implementation, which may be preferred by older userspace
> >applications that
> >+ * do not utilize the newer vhost_task concept.
> >+ */
> >+#define VHOST_FORK_FROM_OWNER _IOW(VHOST_VIRTIO, 0x83, __u8)
> >+
> > #endif
> >--
> >2.45.0
> >
>
