Re: [RFC PATCH 10/24] vdpa: introduce config operations for associating ASID to a virtqueue group

[Jason Wang]

On 2020/10/12 下午4:17, Eli Cohen wrote:
> On Mon, Oct 12, 2020 at 03:45:10PM +0800, Jason Wang wrote:
> > > So in theory we can have several asid's (for different virtqueues), each
> > > one should be followed by a specific set_map call. If this is so, how do
> > > I know if I met all the conditions run my driver? Maybe we need another
> > > callback to let the driver know it should not expect more set_maps().
> >
> > This should work similarly as in the past. Two parts of the work is expected
> > to be done by the driver:
> >
> > 1) store the mapping somewhere (e.g hardware) during set_map()
> > 2) associating mapping with a specific virtqueue
> >
> > The only difference is that more than one mapping is used now.
> ok, so like today, I will always get DRIVER_OK after I got all the
> set_maps(), right?


Yes.

Thanks


> > For the issue of more set_maps(), driver should be always ready for the new
> > set_maps() call instead of not expecting new set_maps() since guest memory
> > topology could be changed due to several reasons.
> >
> > Qemu or vhost-vDPA will try their best to avoid the frequency of set_maps()
> > for better performance (e.g through batched IOTLB updating). E.g there
> > should be at most one set_map() during one time of guest booting.