[Intel-gfx] [PATCH v3 12/12] vfio/pci: Report dev_id in VFIO_DEVICE_GET_PCI_HOT_RESET_INFO

[Liu, Yi L]

> From: Alex Williamson <alex.williamson at redhat.com>
> Sent: Sunday, April 9, 2023 9:30 PM
[...]
> > yeah, needs to move the iommu group creation back to vfio_main.c. This
> > would be a prerequisite for [1]
> >
> > [1] https://lore.kernel.org/kvm/20230401151833.124749-25-yi.l.liu@intel.com/
> >
> > I'll also try out your suggestion to add a capability like below and link
> > it in the vfio_device_info cap chain.
> >
> > #define VFIO_DEVICE_INFO_CAP_PCI_BDF          5
> >
> > struct vfio_device_info_cap_pci_bdf {
> >          struct vfio_info_cap_header header;
> >          __u32   group_id;
> >          __u16   segment;
> >          __u8    bus;
> >          __u8    devfn; /* Use PCI_SLOT/PCI_FUNC */
> > };
> >
> 
> Group-id and bdf should be separate capabilities, all device should
> report a group-id capability and only PCI devices a bdf capability.

ok. Since this is to support the device fd passing usage, so we need to
let all the vfio device drivers report group-id capability. is it? So may
have a below helper in vfio_main.c. How about the sample drivers?
seems not necessary for them. right?

int vfio_pci_info_add_group_cap(struct device *dev,
                                struct vfio_info_cap *caps)
{
        struct vfio_pci_device_info_cap_group cap = {
                .header.id = VFIO_DEVICE_INFO_CAP_GROUP_ID,
                .header.version = 1,
        };
        struct iommu_group *iommu_group;

        iommu_group = iommu_group_get(&pdev->dev);
        if (!iommu_group) {
                kfree(caps->buf);
                return -EPERM;
        }

        cap.group_id = iommu_group_id(iommu_group);

        iommu_group_put(iommu_group);

        return vfio_info_add_capability(caps, &cap.header, sizeof(cap));
}

Regards,
Yi Liu