Messages in this thread | | | Subject | Re: [PATCH v5] vhost: introduce mdev based hardware backend | From | Jason Wang <> | Date | Thu, 7 Nov 2019 12:08:08 +0800 |
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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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