linux-kernel - Re: [PATCH v7 07/10] iommufd: Fault-capable hwpt attach/detach/replace

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Message-ID: <Zn8oZ80p0p1bHgBC@ziepe.ca>
Date: Fri, 28 Jun 2024 18:17:27 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Kevin Tian <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Nicolin Chen <nicolinc@...dia.com>, Yi Liu <yi.l.liu@...el.com>,
	Jacob Pan <jacob.jun.pan@...ux.intel.com>,
	Joel Granados <j.granados@...sung.com>, iommu@...ts.linux.dev,
	virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 07/10] iommufd: Fault-capable hwpt
 attach/detach/replace

On Sun, Jun 16, 2024 at 02:11:52PM +0800, Lu Baolu wrote:
> +static int iommufd_fault_iopf_enable(struct iommufd_device *idev)
> +{
> +	struct device *dev = idev->dev;
> +	int ret;
> +
> +	/*
> +	 * Once we turn on PCI/PRI support for VF, the response failure code
> +	 * should not be forwarded to the hardware due to PRI being a shared
> +	 * resource between PF and VFs. There is no coordination for this
> +	 * shared capability. This waits for a vPRI reset to recover.
> +	 */
> +	if (dev_is_pci(dev) && to_pci_dev(dev)->is_virtfn)
> +		return -EINVAL;

I don't quite get this remark, isn't not supporting PRI on VFs kind of
useless? What is the story here?

Jason