[PATCH v11 1/3] vhost: Add a new parameter in vhost_dev to allow user select kthread
From: Cindy Lu <hidden>
Date: 2025-06-09 07:34:47
Also in:
lkml, netdev
Subsystem:
the rest, virtio host (vhost) · Maintainers:
Linus Torvalds, "Michael S. Tsirkin", Jason Wang, Eugenio Pérez
The vhost now uses vhost_task and workers as a child of the owner thread. While this aligns with containerization principles, it confuses some legacy userspace applications, therefore, we are reintroducing kthread API support. Introduce a new parameter to enable users to choose between kthread and task mode. Signed-off-by: Cindy Lu <redacted> --- drivers/vhost/vhost.c | 2 ++ drivers/vhost/vhost.h | 10 ++++++++++ 2 files changed, 12 insertions(+)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3a5ebb973dba..ff3052858308 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c@@ -41,6 +41,7 @@ static int max_iotlb_entries = 2048; module_param(max_iotlb_entries, int, 0444); MODULE_PARM_DESC(max_iotlb_entries, "Maximum number of iotlb entries. (default: 2048)"); +static bool fork_from_owner_default = true; enum { VHOST_MEMORY_F_LOG = 0x1,
@@ -552,6 +553,7 @@ void vhost_dev_init(struct vhost_dev *dev, dev->byte_weight = byte_weight; dev->use_worker = use_worker; dev->msg_handler = msg_handler; + dev->fork_owner = fork_from_owner_default; init_waitqueue_head(&dev->wait); INIT_LIST_HEAD(&dev->read_list); INIT_LIST_HEAD(&dev->pending_list);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index bb75a292d50c..e3d4732883af 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h@@ -176,6 +176,16 @@ struct vhost_dev { int byte_weight; struct xarray worker_xa; bool use_worker; + /* + * If fork_owner is true we use vhost_tasks to create + * the worker so all settings/limits like cgroups, NPROC, + * scheduler, etc are inherited from the owner. If false, + * we use kthreads and only attach to the same cgroups + * as the owner for compat with older kernels. + * here we use true as default value. + * The default value is set by fork_from_owner_default + */ + bool fork_owner; int (*msg_handler)(struct vhost_dev *dev, u32 asid, struct vhost_iotlb_msg *msg); };
--
2.45.0