Re: [PATCH v1] CHANGELOG.md: Mention PCI passthrough for HVM domUs

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.03.2025 10:48, Roger Pau Monné wrote:
> On Thu, Mar 13, 2025 at 08:42:25AM +0100, Jan Beulich wrote:
>> On 12.03.2025 17:36, Roger Pau Monné wrote:
>>> On Wed, Mar 12, 2025 at 09:51:09AM +0100, Jan Beulich wrote:
>>>> On 12.03.2025 05:02, Jiqian Chen wrote:
>>>>> PCI passthrough is already supported for HVM domUs when dom0 is PVH
>>>>> on x86. The last related patch on Qemu side was merged after Xen4.20
>>>>> release. So mention this feature in Xen4.21 entry.
>>>>>
>>>>> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
>>>>> ---
>>>>>  CHANGELOG.md | 1 +
>>>>>  1 file changed, 1 insertion(+)
>>>>>
>>>>> diff --git a/CHANGELOG.md b/CHANGELOG.md
>>>>> index 7201c484f899..b6de9b72ea7a 100644
>>>>> --- a/CHANGELOG.md
>>>>> +++ b/CHANGELOG.md
>>>>> @@ -12,6 +12,7 @@ The format is based on [Keep a 
>>>>> Changelog](https://keepachangelog.com/en/1.0.0/)
>>>>>   - On x86:
>>>>>     - Option to attempt to fixup p2m page-faults on PVH dom0.
>>>>>     - Resizable BARs is supported for PVH dom0.
>>>>> +   - Support PCI passthrough for HVM domUs when dom0 is PVH.
>>>>
>>>> Aren't we still in need of SR-IOV support in order to make such an
>>>> unconditional statement?
>>>
>>> I view SR-IOV as kind of orthogonal to this: SR-IOV is not
>>> supported at all on PVH dom0, so it's not just pass through, but the
>>> capability itself that won't work as expected when using such devices.
>>
>> Hmm, yes and no. No in so far as I as someone who simply wants to use Xen
>> would read the above statement as indicating full pass-through support.
>> Which first and foremost includes the passing through of VFs.
> 
> Maybe we can clarify somehow that SR-IOV devices are still not
> supported on a PVH dom0:
> 
>  - Support PCI passthrough for HVM domUs when dom0 is PVH (note
>    SR-IOV capability usage is not yet supported on PVH dom0).

I'd prefer if we made this explicit, yes.

> In any case we should likely wait for:
> 
> https://lore.kernel.org/xen-devel/20250308001711.18746-1-jason.andryuk@xxxxxxx/
> 
> To be committed?

Sure - they're in now.

Jan