Re: [PATCH v6 3/8] vpci: Hide legacy capability when it fails to initialize

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.06.2025 11:29, Jiqian Chen wrote:
> --- a/xen/drivers/vpci/vpci.c
> +++ b/xen/drivers/vpci/vpci.c
> @@ -83,6 +83,88 @@ static int assign_virtual_sbdf(struct pci_dev *pdev)
>  
>  #endif /* CONFIG_HAS_VPCI_GUEST_SUPPORT */
>  
> +static struct vpci_register *vpci_get_register(struct vpci *vpci,
> +                                               unsigned int offset,
> +                                               unsigned int size)
> +{
> +    struct vpci_register *r;
> +
> +    ASSERT(spin_is_locked(&vpci->lock));
> +
> +    list_for_each_entry ( r, &vpci->handlers, node )
> +    {
> +        if ( r->offset == offset && r->size == size )
> +            return r;
> +
> +        if ( offset <= r->offset )
> +            break;
> +    }
> +
> +    return NULL;
> +}
> +
> +static struct vpci_register *vpci_get_previous_cap_register(
> +    struct vpci *vpci, unsigned int offset)
> +{
> +    uint32_t next;
> +    struct vpci_register *r;
> +
> +    if ( offset < 0x40 )
> +    {
> +        ASSERT_UNREACHABLE();
> +        return NULL;
> +    }
> +
> +    for ( r = vpci_get_register(vpci, PCI_CAPABILITY_LIST, 1); r;
> +          r = next >= 0x40 ? vpci_get_register(vpci,
> +                                               next + PCI_CAP_LIST_NEXT, 1)
> +                           : NULL )
> +    {
> +        next = (uint32_t)(uintptr_t)r->private;
> +        ASSERT(next == (uintptr_t)r->private);
> +        if ( next == offset )
> +            break;
> +    }
> +
> +    return r;
> +}
> +
> +static int vpci_capability_hide(struct pci_dev *pdev, unsigned int cap)

I really only noticed it in the next patch, but the question applies equally
here: Any reason the first parameter isn't pointer-to-const?

Jan