Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture

[Guilherme Piccoli]

Awesome, thanks a bunch Eduardo!

On Wed, Jun 17, 2020 at 1:33 PM Eduardo Habkost <ehabkost@redhat.com> wrote:
>
> On Wed, Jun 17, 2020 at 12:57:52PM -0300, Guilherme Piccoli wrote:
> > Can't qemu reads the host physical bits and pass that as fw_cfg as
> > "real_host_physbits" or something like that?
> > OVMF could rely on that - if such property is available, we use it to
> > extend the PCI64 aperture.
>
> Giving a exact "real host physbits" value would be too limiting
> if we still want to allow migration to smaller hosts.  But we can
> provide extra information on CPUID or fw_cfg, yes.
>
> I will try to write down a proposal to extend the KVM CPUID leaf
> to provide extra information about MAXPHYADDR guarantees.
>
> --
> Eduardo
>