Re: [PATCH v2] virtio-iommu: Use qemu_real_host_page_mask as default page_size_mask

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Feb 13, 2024 at 12:24:22PM +0100, Eric Auger wrote:
> Hi Michael,
> On 2/13/24 12:09, Michael S. Tsirkin wrote:
> > On Tue, Feb 13, 2024 at 11:32:13AM +0100, Eric Auger wrote:
> >> Do you have an other concern?
> > I also worry a bit about migrating between hosts with different
> > page sizes. Not with kvm I am guessing but with tcg it does work I think?
> I have never tried but is it a valid use case? Adding Peter in CC.
> > Is this just for vfio and vdpa? Can we limit this to these setups
> > maybe?
> I am afraid we know the actual use case too later. If the VFIO device is
> hotplugged we have started working with 4kB granule.
> 
> The other way is to introduce a min_granule option as done for aw-bits.
> But it is heavier.
> 
> Thanks
> 
> Eric
> >

Let's say, if you are changing the default then we definitely want
a way to get the cmpatible behaviour for tcg.
So the compat machinery should be user-accessible too and documented.

-- 
MST