> On 28 Oct 2025, at 00:42, Jason Wang <[email protected]> wrote: > > !-------------------------------------------------------------------| > This Message Is From an External Sender > This message came from outside your organization. > |-------------------------------------------------------------------! > > On Mon, Oct 27, 2025 at 6:27 PM Nick Hudson <[email protected]> wrote: >> >> The vhost_net (and vhost_sock) drivers create worker tasks to handle >> the virtual queues. Provide a new ioctl VHOST_GET_VRING_WORKER_INFO that >> can be used to determine the PID of these tasks so that, for example, >> they can be pinned to specific CPU(s). >> >> Signed-off-by: Nick Hudson <[email protected]> >> Reviewed-by: Max Tottenham <[email protected]> >> --- >> drivers/vhost/net.c | 5 +++++ >> drivers/vhost/vhost.c | 16 ++++++++++++++++ >> include/uapi/linux/vhost.h | 3 +++ >> include/uapi/linux/vhost_types.h | 13 +++++++++++++ >> kernel/vhost_task.c | 12 ++++++++++++ >> 5 files changed, 49 insertions(+) >> >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >> index 35ded4330431..e86bd5d7d202 100644 >> --- a/drivers/vhost/net.c >> +++ b/drivers/vhost/net.c >> @@ -1804,6 +1804,11 @@ static long vhost_net_ioctl(struct file *f, unsigned >> int ioctl, >> return vhost_net_reset_owner(n); >> case VHOST_SET_OWNER: >> return vhost_net_set_owner(n); >> + case VHOST_GET_VRING_WORKER_INFO: >> + mutex_lock(&n->dev.mutex); >> + r = vhost_worker_ioctl(&n->dev, ioctl, argp); >> + mutex_unlock(&n->dev.mutex); >> + return r; >> default: >> mutex_lock(&n->dev.mutex); >> r = vhost_dev_ioctl(&n->dev, ioctl, argp); >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >> index 8570fdf2e14a..8b52fd5723c3 100644 >> --- a/drivers/vhost/vhost.c >> +++ b/drivers/vhost/vhost.c >> @@ -2399,6 +2399,22 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned >> int ioctl, void __user *argp) >> if (ctx) >> eventfd_ctx_put(ctx); >> break; >> + case VHOST_GET_VRING_WORKER_INFO: >> + worker = rcu_dereference_check(vq->worker, >> + lockdep_is_held(&dev->mutex)); >> + if (!worker) { >> + ret = -EINVAL; >> + break; >> + } >> + >> + memset(&ring_worker_info, 0, sizeof(ring_worker_info)); >> + ring_worker_info.index = idx; >> + ring_worker_info.worker_id = worker->id; >> + ring_worker_info.worker_pid = >> task_pid_vnr(vhost_get_task(worker->vtsk)); >> + >> + if (copy_to_user(argp, &ring_worker_info, >> sizeof(ring_worker_info))) >> + ret = -EFAULT; >> + break; >> default: >> r = -ENOIOCTLCMD; >> break; >> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h >> index c57674a6aa0d..c32aa8c71952 100644 >> --- a/include/uapi/linux/vhost.h >> +++ b/include/uapi/linux/vhost.h >> @@ -101,6 +101,9 @@ >> /* Return the vring worker's ID */ >> #define VHOST_GET_VRING_WORKER _IOWR(VHOST_VIRTIO, 0x16, \ >> struct vhost_vring_worker) >> +/* Return the vring worker's ID and PID */ >> +#define VHOST_GET_VRING_WORKER_INFO _IOWR(VHOST_VIRTIO, 0x17, \ >> + struct vhost_vring_worker_info) >> >> /* The following ioctls use eventfd file descriptors to signal and poll >> * for events. */ >> diff --git a/include/uapi/linux/vhost_types.h >> b/include/uapi/linux/vhost_types.h >> index 1c39cc5f5a31..28e00f8ade85 100644 >> --- a/include/uapi/linux/vhost_types.h >> +++ b/include/uapi/linux/vhost_types.h >> @@ -63,6 +63,19 @@ struct vhost_vring_worker { >> unsigned int worker_id; >> }; >> >> +/* Per-virtqueue worker mapping entry */ >> +struct vhost_vring_worker_info { >> + /* vring index */ >> + unsigned int index; >> + /* >> + * The id of the vhost_worker returned from VHOST_NEW_WORKER or >> + * allocated as part of vhost_dev_set_owner. >> + */ >> + unsigned int worker_id; > > I'm not sure the above two are a must and exposing internal workd_id > seems not like a good idea.
It’s already exposed by VHOST_NEW_WORKER, but happy to drop it if you prefer. > >> + >> + __kernel_pid_t worker_pid; /* PID/TID of worker thread, -1 if none >> */ > > Instead of exposing the worker PID, I wonder if it's simple to just > having a better naming of the worker instead of a simple: > > snprintf(name, sizeof(name), "vhost-%d", current->pid); This is currently the case drivers/vhost/vhost.c: snprintf(name, sizeof(name), "vhost-%d", current->pid); I was hoping to add the IOCTL, use in qemu, and expose it via QMP/HMP. I have changes to qemu that do this. Thanks, Nick
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