Re: [RFC XEN PATCH v4 5/5] libxl: Use gsi instead of irq for mapping pirq

[Jan Beulich]

On 05.01.2024 08:09, Jiqian Chen wrote:
> --- a/tools/libs/light/libxl_pci.c
> +++ b/tools/libs/light/libxl_pci.c
> @@ -1479,8 +1479,14 @@ static void pci_add_dm_done(libxl__egc *egc,
>      fclose(f);
>      if (!pci_supp_legacy_irq())
>          goto out_no_irq;
> -    sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/irq", pci->domain,
> +    sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/gsi", pci->domain,
>                                  pci->bus, pci->dev, pci->func);
> +
> +    if (access(sysfs_path, F_OK) != 0) {

I suppose you want to also check errno, and fall back only when you got
back (I guess) ENOENT.

Jan

> +        sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/irq", pci->domain,
> +                                pci->bus, pci->dev, pci->func);
> +    }
> +
>      f = fopen(sysfs_path, "r");
>      if (f == NULL) {
>          LOGED(ERROR, domainid, "Couldn't open %s", sysfs_path);
> @@ -2231,9 +2237,14 @@ skip_bar:
>      if (!pci_supp_legacy_irq())
>          goto skip_legacy_irq;
>  
> -    sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/irq", pci->domain,
> +    sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/gsi", pci->domain,
>                             pci->bus, pci->dev, pci->func);
>  
> +    if (access(sysfs_path, F_OK) != 0) {
> +        sysfs_path = GCSPRINTF(SYSFS_PCI_DEV"/"PCI_BDF"/irq", pci->domain,
> +                           pci->bus, pci->dev, pci->func);
> +    }
> +
>      f = fopen(sysfs_path, "r");
>      if (f == NULL) {
>          LOGED(ERROR, domid, "Couldn't open %s", sysfs_path);