Re: [PATCH v8 07/10] iommufd: Fault-capable hwpt attach/detach/replace

[Baolu Lu]

On 2024/10/17 21:08, Jason Gunthorpe wrote:
> On Thu, Oct 17, 2024 at 08:35:24PM +0800, Zhangfei Gao wrote:
>
> > Yes, you are right
> >   I am using SRIOV vf and stall feature, so is_virtfn == true
> >
> > Our ACC devices are fake pci endpoint devices which supports stall,
> > And they also supports sriov
> >
> > So I have to ignore the limitation.
> I see, so that is more complicated.
>
> Lu, what do you think about also checking if the PCI function has PRI
> ? If not PRI assume the fault is special and doesn't follow PRI rules?
>
> Or maybe we can have the iommu driver tag the event as a PRI/not-PRI
> fault?

This limitation applies to PRI on PCI/SRIOV VFs because the PRI might be
a shared resource and current iommu subsystem is not ready to support
enabling/disabling PRI on a VF without any impact on others.

In my understanding, it's fine to remove this limitation from the use
case of non-PRI on SRIOV VFs. Perhaps something like below?

	if (dev_is_pci(dev)) {
		struct pci_dev *pdev = to_pci_dev(dev);
		if (pdev->is_virtfn && pci_pri_supported(pdev))
			return -EINVAL;
	}

Thanks,
baolu