On 09.04.2025 08:45, Jiqian Chen wrote:
> --- a/xen/drivers/vpci/header.c
> +++ b/xen/drivers/vpci/header.c
> @@ -815,6 +815,39 @@ static int vpci_init_capability_list(struct pci_dev
> *pdev)
> return rc;
> }
>
> +static int vpci_init_ext_capability_list(struct pci_dev *pdev)
> +{
> + int rc;
> + u32 header;
> + unsigned int pos = 0x100U, ttl = 480;
> +
> + if ( !is_hardware_domain(pdev->domain) )
> + {
> + /* Extended capabilities read as zero, write ignore */
> + rc = vpci_add_register(pdev->vpci, vpci_read_val, NULL,
> + pos, 4, (void *)0);
> + if ( rc )
> + return rc;
> + }
> +
> + while ( pos && ttl-- )
> + {
> + header = pci_conf_read32(pdev->sbdf, pos);
> +
> + rc = vpci_add_register(pdev->vpci, vpci_read_val, NULL,
> + pos, 4, (void *)(uintptr_t)header);
> + if ( rc )
> + return rc;
> +
> + if ( (header == 0) || (header == -1) )
> + return 0;
I realize pci_find_next_ext_capability() also has such a check, but even
there it's not really clear to me why compare not only against 0, but also
again -1 (aka ~0).
Jan
