Re: [PATCH v5 5/9] iommufd: Add iommufd fault object

[Baolu Lu <baolu.lu@linux.intel.com>]

On 5/15/24 4:37 PM, Tian, Kevin wrote:
>> +
>> +		iopf_group_response(group, response.code);
> PCIe spec states that a response failure disables the PRI interface. For SR-IOV
> it'd be dangerous allowing user to trigger such code to VF to close the entire
> shared PRI interface.
> 
> Just another example lacking of coordination for shared capabilities between
> PF/VF. But exposing such gap to userspace makes it worse.

Yes. You are right.

> 
> I guess we don't want to make this work depending on that cleanup. The
> minimal correct thing is to disallow attaching VF to a fault-capable hwpt
> with a note here that once we turn on support for VF the response failure
> code should not be forwarded to the hardware. Instead it's an indication
> that the user cannot serve more requests and such situation waits for
> a vPRI reset to recover.

Is it the same thing to disallow PRI for VF in IOMMUFD?

Best regards,
baolu