[libvirt] [PATCH v6 00/13] PCI passthrough support on s390

[Daniel P. Berrangé]

On Fri, Sep 28, 2018 at 04:46:13PM +0800, Yi Min Zhao wrote:
> Abstract
> ========
> The PCI representation in QEMU has recently been extended for S390
> allowing configuration of zPCI attributes like uid (user-defined
> identifier) and fid (PCI function identifier).
> The details can be found here:
> https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg07262.html
> 
> To support the new zPCI feature of the S390 platform, a new element of
> PCI address is introduced. It has two optional attributes, @uid and
> @fid. For example:
>   <hostdev mode='subsystem' type='pci'>
>     <driver name='vfio'/>
>     <source>
>       <address domain='0x0001' bus='0x00' slot='0x00' function='0x0'/>
>     </source>
>     <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'>
>       <zpci uid='0x0003' fid='0x00000027'/>
>     </address>
>   </hostdev>

I'm not sure if this was discussed in earlier versions, but to me
this use of a child element looks wrong.

What we're effectively saying is that s390 has a different addressing
scheme. It happens to share some fields with the current PCI addressing
scheme, but it is none the less a distinct scheme.

IOW, I think it should be

   <address type='zpci' domain='0x0000' bus='0x00' slot='0x01'
                        function='0x0' uid='0x0003' fid='0x00000027'/>


Of course internally we can still share much logic for assigning the
addreses between "pci" and "zpci".

Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|