Re: [PATCH for-4.21] tools/libxc: fix xc_physdev_map_pirq_msi() with PCI segments != 0

[Frediano Ziglio <freddy77@xxxxxxxxx>]

On Fri, Oct 17, 2025 at 3:26 PM Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:
>
> Otherwise it's not possible for device models to map IRQs of devices on
> segments different than 0.  Keep the same function prototype and pass the
> segment in the high 16bits of the bus parameter, like it's done for the
> hypercall itself.
>
> Fixes: 7620c0cf9a4d ("PCI multi-seg: add new physdevop-s")
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> I think it's 4.21 material, as otherwise it's not possible to passthrough
> PCI devices on segments != 0.
> ---
>  tools/libs/ctrl/xc_physdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/libs/ctrl/xc_physdev.c b/tools/libs/ctrl/xc_physdev.c
> index 25e686d7b389..1307d6836d72 100644
> --- a/tools/libs/ctrl/xc_physdev.c
> +++ b/tools/libs/ctrl/xc_physdev.c
> @@ -79,7 +79,7 @@ int xc_physdev_map_pirq_msi(xc_interface *xch,
>      }
>      memset(&map, 0, sizeof(struct physdev_map_pirq));
>      map.domid = domid;
> -    map.type = MAP_PIRQ_TYPE_MSI;
> +    map.type = MAP_PIRQ_TYPE_MSI_SEG;
>      map.index = index;
>      map.pirq = *pirq;
>      map.bus = bus;

Reviewed-by: Frediano Ziglio <frediano.ziglio@xxxxxxxxx>

This was tested on a real machine.

About MAP_PIRQ_TYPE_MSI and MAP_PIRQ_TYPE_MSI_SEG, do we need to keep
ABI compatibility or we should just remove MAP_PIRQ_TYPE_MSI_SEG and
make MAP_PIRQ_TYPE_MSI consider the segment ?

Frediano