Re: [PATCH v3 7/9] vhost: Add new UAPI to support change to task mode
From: Stefano Garzarella <sgarzare@redhat.com>
Date: 2024-11-05 10:32:09
Also in:
lkml, virtualization
On Tue, Nov 05, 2024 at 03:25:26PM +0800, Cindy Lu wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- drivers/vhost/vhost.c | 15 ++++++++++++++- include/uapi/linux/vhost.h | 2 ++ 2 files changed, 16 insertions(+), 1 deletion(-)diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index c17dc01febcc..70c793b63905 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c@@ -2274,8 +2274,9 @@ 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;
I don't know if something is missing in this patch, but I am confused: `r` is set few lines below...
int i, fd;
+ bool inherit_owner;
/* If you are not the owner, you can become one */
if (ioctl == VHOST_SET_OWNER) {... /* You must be the owner to do anything else */ r = vhost_dev_check_owner(d); if (r) goto done; So, why we are now initializing it to 0?
quoted hunk ↗ jump to hunk
@@ -2332,6 +2333,18 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)if (ctx) eventfd_ctx_put(ctx); break; + case VHOST_SET_INHERIT_FROM_OWNER: + /*inherit_owner can only be modified before owner is set*/ + if (vhost_dev_has_owner(d))
And here, how this check can be false, if at the beginning of the function we call vhost_dev_check_owner()? Maybe your intention was to add this code before the `vhost_dev_check_owner()` call, so this should explain why initialize `r` to 0, but I'm not sure.
+ break;
Should we return an error (e.g. -EPERM) in this case?
quoted hunk ↗ jump to hunk
+ + if (copy_from_user(&inherit_owner, argp, + sizeof(inherit_owner))) { + r = -EFAULT; + break; + } + d->inherit_owner = inherit_owner; + break; default: r = -ENOIOCTLCMD; break;diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h index b95dd84eef2d..1e192038633d 100644 --- a/include/uapi/linux/vhost.h +++ b/include/uapi/linux/vhost.h@@ -235,4 +235,6 @@ */#define VHOST_VDPA_GET_VRING_SIZE _IOWR(VHOST_VIRTIO, 0x82, \ struct vhost_vring_state) +
Please add a documentation here, this is UAPI, so the user should know what this ioctl does based on the parameter. Thanks, Stefano
+#define VHOST_SET_INHERIT_FROM_OWNER _IOW(VHOST_VIRTIO, 0x83, bool) #endif -- 2.45.0