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