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

[Bernhard Beschow <shentey@xxxxxxxxx>]

Am 7. Januar 2024 23:16:23 UTC schrieb Bernhard Beschow <shentey@xxxxxxxxx>:
>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>

Hi Michael,

could you tag this, too? Or do we need another R-b?

Best regards,
Bernhard

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