[libvirt] [PATCH v2 RESEND 00/12] PCI passthrough support on s390

[Cornelia Huck]

On Tue, 10 Jul 2018 16:02:14 +0800
Yi Min Zhao <zyimin at linux.ibm.com> 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, two new XML
> attributes, @uid and @fid, are introduced for device addresses of type
> 'pci', i.e.:
>   <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'
>       uid='0x0003' fid='0x00000027'/>
>   </hostdev>
> 
> uid and fid are optional attributes. If they are defined by the user,
> unique values within the guest domain must be used. If they are not
> specified and the architecture requires them, they are automatically
> generated with non-conflicting values.
> 
> Current implementation is the most seamless one for the user as it
> unites the address specific data of a PCI device on one XML element.
> It could accommodate both specifying our special parameters (uid and fid)
> and re-using standard statements (domain, bus, slot and function) for
> PCI devices. User can still specify bus/slot/function for the virtualized
> PCI devices in the XML.
> 
> Thus uid/fid act as an extension to the PCI address and are stored in
> a new structure 'virZPCIDeviceAddress' which is a member of common PCI
> Address structure. Additionally, two hashtables are used for assignment
> and reservation of uid/fid.
> 
> In support of extending the PCI address, a new PCI address extension flag is
> introduced. This extension flag allows is not only dedicated for the S390
> platform but also other architectures needing certain extensions to PCI
> address space.

FWIW, from my QEMU POV there's nothing obviously wrong in here, but I'm
not familiar with the libvirt code base. So I'll leave this to the
libvirt developers.