Re: [RFC XEN PATCH v9 5/5] domctl: Add XEN_DOMCTL_gsi_permission to grant gsi

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

On 2024/6/14 14:41, Jan Beulich wrote:
> On 14.06.2024 05:11, Chen, Jiqian wrote:
>> On 2024/6/13 20:51, Anthony PERARD wrote:
>>> On Wed, Jun 12, 2024 at 10:55:14AM +0000, Chen, Jiqian wrote:
>>>> On 2024/6/12 18:34, Jan Beulich wrote:
>>>>> On 12.06.2024 12:12, Chen, Jiqian wrote:
>>>>>> On 2024/6/11 22:39, Jan Beulich wrote:
>>>>>>> On 07.06.2024 10:11, Jiqian Chen wrote:
>>>>>>>> +    r = xc_domain_gsi_permission(ctx->xch, domid, gsi, map);
>>>>>>>
>>>>>>> Looking at the hypervisor side, this will fail for PV Dom0. In which 
>>>>>>> case imo
>>>>>>> you better would avoid making the call in the first place.
>>>>>> Yes, for PV dom0, the errno is EOPNOTSUPP, then it will do below 
>>>>>> xc_domain_irq_permission.
>>>>>
>>>>> Hence why call xc_domain_gsi_permission() at all on a PV Dom0?
>>>> Is there a function to distinguish that current dom0 is PV or PVH dom0 in 
>>>> tools/libs?
>>>
>>> That might have never been needed before, so probably not. There's
>>> libxl__domain_type() but if that works with dom0 it might return "HVM"
>>> for PVH dom0. So if xc_domain_getinfo_single() works and give the right
>>> info about dom0, libxl__domain_type() could be extended to deal with
>>> dom0 I guess. I don't know if there's a good way to find out which
>>> flavor of dom0 is running.
>> Thanks Anthony!
>> I think here we really need to check is that whether current domain has PIRQ 
>> flag(X86_EMU_USE_PIRQ) or not.
>> And it seems xc_domain_gsi_permission already return the information.
> 
> By way of failing, if I'm not mistaken? As indicated before, I don't
> think you should invoke the function when it's clear it's going to fail.
Sorry, I wrote wrong here, it should be " And it seems xc_domain_getinfo_single 
already return the information."
And next version will be like:
xc_domaininfo_t xcinfo;
xc_domain_getinfo_single(xc_handle, domid, &xcinfo);
if( xcinfo.arch_config.emulation_flags & XEN_X86_EMU_USE_PIRQ )
        xc_domain_irq_permission
else
        xc_domain_gsi_permission

> 
> Jan
> 
>> If current domain has no PIRQs, then I should use xc_domain_gsi_permission 
>> to grant permission, otherwise I should
>> keep the original function xc_domain_irq_permission.
>>
>>>
>>> Cheers,
>>>
>>
> 

-- 
Best regards,
Jiqian Chen.