On 12.06.2025 11:29, Jiqian Chen wrote:
> +static int vpci_ext_capability_hide(struct pci_dev *pdev, unsigned int cap)
> +{
> + const unsigned int offset = pci_find_ext_capability(pdev->sbdf, cap);
> + struct vpci_register *r, *prev_r;
> + struct vpci *vpci = pdev->vpci;
> + uint32_t header, pre_header;
> +
> + if ( offset < PCI_CFG_SPACE_SIZE )
> + {
> + ASSERT_UNREACHABLE();
> + return 0;
> + }
> +
> + spin_lock(&vpci->lock);
> + r = vpci_get_register(vpci, offset, 4);
> + if ( !r )
> + {
> + spin_unlock(&vpci->lock);
> + return -ENODEV;
> + }
> +
> + header = (uint32_t)(uintptr_t)r->private;
> + if ( offset == PCI_CFG_SPACE_SIZE )
> + {
> + if ( PCI_EXT_CAP_NEXT(header) <= PCI_CFG_SPACE_SIZE )
> + r->private = (void *)(uintptr_t)0;
> + else
> + /*
> + * The first extended capability (0x100) can not be removed from
> + * the linked list, so instead mask its capability ID to return 0
> + * and force OSes to skip it.
> + */
> + r->private = (void *)(uintptr_t)(header &
> ~PCI_EXT_CAP_ID(header));
Can we rely on OSes recognizing ID 0 as "just skip"? Since the size isn't
encoded
in the header, there might be issues lurking here.
Jan
