On 2019/11/6 下午10:49, Tiwei Bie wrote:
+ default:
+ /*
+ * VHOST_SET_MEM_TABLE, VHOST_SET_LOG_BASE, and
+ * VHOST_SET_LOG_FD are not used yet.
+ */
If we don't even use them, there's probably no need to call
vhost_dev_ioctl(). This may help to avoid confusion when we want to develop
new API for e.g dirty page tracking.
Good point. It's better to reject these ioctls for now.
PS. One thing I may need to clarify is that, we need the
VHOST_SET_OWNER ioctl to get the vq->handle_kick to work.
So if we don't call vhost_dev_ioctl(), we will need to
call vhost_dev_set_owner() directly.
I may miss something, it looks to me the there's no owner check in
vhost_vring_ioctl() and the vhost_poll_start() can make sure handle_kick
works?
Yeah, there is no owner check in vhost_vring_ioctl().
IIUC, vhost_poll_start() will start polling the file. And when
event arrives, vhost_poll_wakeup() will be called, and it will
queue work to work_list and wakeup worker to finish the work.
And the worker is created by vhost_dev_set_owner().
Right, rethink about this. It looks to me we need:
- Keep VHOST_SET_OWNER, this could be used for future control vq where
it needs a kthread to access the userspace memory
- Temporarily filter SET_LOG_BASE and SET_LOG_FD until we finalize the
API for dirty page tracking.
- For kick through kthread, it looks sub-optimal but we can address this
in the future, e.g call handle_vq_kick directly in vhost_poll_queue
(probably a flag for vhost_poll) and deal with the synchronization in
vhost_poll_flush carefully.
Thanks
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