On Thu, Jun 22, 2023 at 9:39 PM Laurent Vivier <lviv...@redhat.com> wrote:
>
> On 6/22/23 15:12, Peter Maydell wrote:
> > On Tue, 20 Jun 2023 at 20:51, Laurent Vivier <lviv...@redhat.com> wrote:
> >>
> >> This memory is not correctly aligned and cannot be registered
> >> by vDPA and VFIO.
> >
> > Isn't this a vDPA/VFIO problem? There's no requirement
> > for RAM MemoryRegions to be aligned in any way.
It's more about the limitation of the IOMMU which can't do subpage protection.
> > Code
> > that doesn't want to work with small or weirdly aligned
> > regions should skip them if that's the right behaviour
> > for that particular code IMHO.
We had already had this:
if ((!memory_region_is_ram(section->mr) &&
!memory_region_is_iommu(section->mr)) ||
memory_region_is_protected(section->mr) ||
/* vhost-vDPA doesn't allow MMIO to be mapped */
memory_region_is_ram_device(section->mr)) {
return true;
}
> >
>
> Marc-André proposed to modify vDPA code to skip the region but Michal
> disagreed:
>
> https://lists.nongnu.org/archive/html/qemu-devel/2022-11/msg03670.html
>
> No one wants the modification, so the problem cannot be fixed.
>
Yes, otherwise we end up with explicit check for TPM crb in vhost code...
Thanks
> Thanks,
> Laurent
>
