On 2024/6/29 5:17, Jason Gunthorpe wrote:
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?
This remark is trying to explain why attaching an iopf-capable hwpt to a VF is not supported for now. The PCI sepc (section 10.4.2.1) states that a response failure will disable the PRI on the function. But for PF/VF case, the PRI is a shared resource, therefore a response failure on a VF might cause iopf on other VFs to malfunction. So, we start from simple by not allowing it. Best regards, baolu
