Re: [PATCH, RFC 0/7] PCI multi-segment support

[Keir Fraser <keir.xen@gmail.com>]

On 05/09/2011 14:18, "Jan Beulich" <JBeulich@suse.com> wrote:

>>>> On 25.08.11 at 16:54, "Jan Beulich" <JBeulich@novell.com> wrote:
>> In order for Xen to be able to boot on systems with multiple PCI segments
>> (also called domains), a number of changes are necessary to the
>> hypervisor, the hypercall interface, the tools, and the Dom0 kernel, as
>> in most code paths and definitions there were not even provisions for
>> passing a segment number.
>> 
>> The hypercall interface changes may need some discussion before
>> applying the patches, in particular
>> 
>> - whether the way PHYSDEVOP_map_pirq gets re-used is acceptable,
>>   or whether alternatively we should define a replacement one sub-
>>   hypercall
>> - whether PHYSDEVOP_manage_pci_* should be deprecated
>> - whether the bit assignments for the four uses of machine_bdf in
>>   the domctl interface can be re-defined
> 
> No comment from either of you on the proposed changes?

I'm personally fine with folding segment into the bus field. Otherwise we
just end up with more compat cruft.

I don't have an opinion on the PHYSDEVOP_manage_pci_* hypercalls. In fact I
don't know much about them at all.

I've always considered the domctl interface subject to change, but you don't
seem to redefine anything that already exists? You just give meaning to bits
24-31 of an existing 32-bit parameter?

 -- Keir

> Jan
> 
>> Additionally, in the AMD IOMMU code there are two places where I
>> was unable to identify how the segment value ought to be retrieved.
>> Since I'm unaware of multi-segment AMD-based systems, imo this
>> should not be a reason to not commit the changes proposed.
>> 
>> 1: introduce notion of PCI segments
>> 2: add new physdevop-s
>> 3: adjust domctl interface
>> 4: VT-d specific adjustments
>> 5: AMD-IOMMU specific adjustments
>> 6: Pass-through adjustments
>> 7: config space accessor adjustments
>> 
>> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>