Re: [PATCH] hw/i386/pc_piix: Make piix_intx_routing_notifier_xen() more device independent

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

On 8/1/24 00:16, Bernhard Beschow wrote:
> This is a follow-up on commit 89965db43cce "hw/isa/piix3: Avoid Xen-specific
> variant of piix3_write_config()" which introduced
> piix_intx_routing_notifier_xen(). This function is implemented in board code but
> accesses the PCI configuration space of the PIIX ISA function to determine the
> PCI interrupt routes. Avoid this by reusing pci_device_route_intx_to_irq() which
> makes piix_intx_routing_notifier_xen() more device-agnostic.
>
> One remaining improvement would be making piix_intx_routing_notifier_xen()
> agnostic towards the number of PCI interrupt routes and move it to xen-hvm.
> This might be useful for possible Q35 Xen efforts but remains a future exercise
> for now.
>
> Signed-off-by: Bernhard Beschow <shentey@xxxxxxxxx>
> ---
>   hw/i386/pc_piix.c | 9 +++------
>   1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 042c13cdbc..abfcfe4d2b 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -92,13 +92,10 @@ static void piix_intx_routing_notifier_xen(PCIDevice *dev)
>   {
>       int i;
>   
> -    /* Scan for updates to PCI link routes (0x60-0x63). */
> +    /* Scan for updates to PCI link routes. */
>       for (i = 0; i < PIIX_NUM_PIRQS; i++) {
> -        uint8_t v = dev->config_read(dev, PIIX_PIRQCA + i, 1);
> -        if (v & 0x80) {
> -            v = 0;
> -        }
> -        v &= 0xf;
> +        const PCIINTxRoute route = pci_device_route_intx_to_irq(dev, i);
This indeed dispatch to piix_route_intx_pin_to_irq().

Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>

> +        const uint8_t v = route.mode == PCI_INTX_ENABLED ? route.irq : 0;
>           xen_set_pci_link_route(i, v);
>       }
>   }