On Fri, Sep 27, 2019 at 09:17:56PM +0800, Jason Wang wrote: > > On 2019/9/27 下午8:46, Michael S. Tsirkin wrote: > > On Fri, Sep 27, 2019 at 08:17:47PM +0800, Jason Wang wrote: > > > On 2019/9/27 下午5:41, Michael S. Tsirkin wrote: > > > > On Fri, Sep 27, 2019 at 11:27:12AM +0800, Jason Wang wrote: > > > > > On 2019/9/26 下午9:14, Tiwei Bie wrote: > > > > > > On Thu, Sep 26, 2019 at 04:35:18AM -0400, Michael S. Tsirkin wrote: > > > > > > > On Thu, Sep 26, 2019 at 12:54:27PM +0800, Tiwei Bie wrote: > > > > > > [...] > > > > > > > > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h > > > > > > > > index 40d028eed645..5afbc2f08fa3 100644 > > > > > > > > --- a/include/uapi/linux/vhost.h > > > > > > > > +++ b/include/uapi/linux/vhost.h > > > > > > > > @@ -116,4 +116,12 @@ > > > > > > > > #define VHOST_VSOCK_SET_GUEST_CID _IOW(VHOST_VIRTIO, 0x60, __u64) > > > > > > > > #define VHOST_VSOCK_SET_RUNNING _IOW(VHOST_VIRTIO, 0x61, int) > > > > > > > > +/* VHOST_MDEV specific defines */ > > > > > > > > + > > > > > > > > +#define VHOST_MDEV_SET_STATE _IOW(VHOST_VIRTIO, 0x70, __u64) > > > > > > > > + > > > > > > > > +#define VHOST_MDEV_S_STOPPED 0 > > > > > > > > +#define VHOST_MDEV_S_RUNNING 1 > > > > > > > > +#define VHOST_MDEV_S_MAX 2 > > > > > > > > + > > > > > > > > #endif > > > > > > > So assuming we have an underlying device that behaves like virtio: > > > > > > I think they are really good questions/suggestions. Thanks! > > > > > > > > > > > > > 1. Should we use SET_STATUS maybe? > > > > > > I like this idea. I will give it a try. > > > > > > > > > > > > > 2. Do we want a reset ioctl? > > > > > > I think it is helpful. If we use SET_STATUS, maybe we > > > > > > can use it to support the reset. > > > > > > > > > > > > > 3. Do we want ability to enable rings individually? > > > > > > I will make it possible at least in the vhost layer. > > > > > Note the API support e.g set_vq_ready(). > > > > virtio spec calls this "enabled" so let's stick to that. > > > > > > Ok. > > > > > > > > > > > > > 4. Does device need to limit max ring size? > > > > > > > 5. Does device need to limit max number of queues? > > > > > > I think so. It's helpful to have ioctls to report the max > > > > > > ring size and max number of queues. > > > > > An issue is the max number of queues is done through a device specific way, > > > > > usually device configuration space. This is supported by the transport API, > > > > > but how to expose it to userspace may need more thought. > > > > > > > > > > Thanks > > > > an ioctl for device config? But for v1 I'd be quite happy to just have > > > > a minimal working device with 2 queues. > > > > > > I'm fully agree, and it will work as long as VIRTIO_NET_F_MQ and > > > VIRTIO_NET_F_CTRL_VQ is not advertised by the mdev device. > > > > > > Thanks > > Hmm this means we need to validate the features bits, > > not just pass them through to the hardware. > > Problem is, how do we add more feature bits later, > > without testing all hardware? > > I guess this means the device specific driver must do it. > > > > That looks not good, maybe a virtio device id based features blacklist in > vhost-mdev. Then MQ and CTRL_VQ could be filtered out by vhost-mdev. > > Thanks Two implementations of e.g. virtio net can have different features whitelisted. So I think there's no way but let the driver do it. We should probably provide a standard place in the ops for driver to supply the whitelist, to make sure drivers don't forget. > > > > > > > Thanks!
