Re: [PATCH v5 07/11] xen/domctl: Introduce XEN_DOMCTL_CDF_vpci flag

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Roger,

On 11.10.2021 11:27, Roger Pau Monné wrote:
> On Wed, Oct 06, 2021 at 06:40:33PM +0100, Rahul Singh wrote:
>> Introduce XEN_DOMCTL_CDF_vpci flag to enable VPCI support in XEN.
>> Reject the use of this new flag for x86 as VPCI is not supported for
>> DOMU guests for x86.
> 
> I don't like this approach, XEN_DOMCTL_CDF_vpci should be set for x86
> PVH dom0, like we do for any other CDF flags when Xen builds dom0.
> 
> Things like PVH vs PV get translated into CDF flags by create_dom0,
> and processed normally by the sanitise_domain_config logic, vPCI
> should be handled that way.
> 
> Do you think you could see about fixing this?
> 
> Thanks, Roger.
> 

I have one question about this fix.
If I set XEN_DOMCTL_CDF_vpci for dom0 pvh in create_dom0, then in
sanitise_domain_config or arch_sanitise_domain_config I have no
knowledge on whether I am dom0 or not. I can check if I'm PVH but not if dom0.
This would be needed to add a warning if this flag is set but we are not dom0 
pvh.

Any ideas?

Cheers,
Michal