Re: [PATCH] xen/pciback: Make missing GSI non-fatal

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

On 2025/2/27 04:01, Jason Andryuk wrote:
> A PCI may not have a legacy IRQ.  In that case, do not fail assigning
> to the pciback stub.  Instead just skip xen_pvh_setup_gsi().
> 
> This will leave psdev->gsi == -1.  In that case, when reading the value
> via IOCTL_PRIVCMD_PCIDEV_GET_GSI, return -ENOENT.  Userspace can used
> this to distinquish from other errors.
> 
> Fixes: b166b8ab4189 ("xen/pvh: Setup gsi for passthrough device")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> ---
>  drivers/xen/acpi.c                 |  4 ++--
>  drivers/xen/xen-pciback/pci_stub.c | 17 ++++++++++-------
>  2 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/xen/acpi.c b/drivers/xen/acpi.c
> index d2ee605c5ca1..d6ab0cb3ba3f 100644
> --- a/drivers/xen/acpi.c
> +++ b/drivers/xen/acpi.c
> @@ -101,7 +101,7 @@ int xen_acpi_get_gsi_info(struct pci_dev *dev,
>  
>       pin = dev->pin;
>       if (!pin)
> -             return -EINVAL;
> +             return -ENOENT;
>  
>       entry = acpi_pci_irq_lookup(dev, pin);
>       if (entry) {
> @@ -116,7 +116,7 @@ int xen_acpi_get_gsi_info(struct pci_dev *dev,
>               gsi = -1;
>  
>       if (gsi < 0)
> -             return -EINVAL;
> +             return -ENOENT;
>  
>       *gsi_out = gsi;
>       *trigger_out = trigger;
> diff --git a/drivers/xen/xen-pciback/pci_stub.c 
> b/drivers/xen/xen-pciback/pci_stub.c
> index b616b7768c3b..9715c2f70586 100644
> --- a/drivers/xen/xen-pciback/pci_stub.c
> +++ b/drivers/xen/xen-pciback/pci_stub.c
> @@ -240,6 +240,9 @@ static int pcistub_get_gsi_from_sbdf(unsigned int sbdf)
>       if (!psdev)
>               return -ENODEV;
>  
> +     if (psdev->gsi == -1)
> +             return -ENOENT;
> +
>       return psdev->gsi;
>  }
>  #endif
> @@ -475,14 +478,14 @@ static int pcistub_init_device(struct pcistub_device 
> *psdev)
>  #ifdef CONFIG_XEN_ACPI
>       if (xen_initial_domain() && xen_pvh_domain()) {
>               err = xen_acpi_get_gsi_info(dev, &gsi, &trigger, &polarity);
> -             if (err) {
> -                     dev_err(&dev->dev, "Fail to get gsi info!\n");
> -                     goto config_release;
> +             if (err && err != -ENOENT) {
> +                     dev_err(&dev->dev, "Failed to get gsi info! %d\n", err);
I think here needs " goto config_release;" since it is not ENOENT error.

> +             } else if (!err) {
> +                     err = xen_pvh_setup_gsi(gsi, trigger, polarity);
> +                     if (err)
> +                             goto config_release;
> +                     psdev->gsi = gsi;
>               }
> -             err = xen_pvh_setup_gsi(gsi, trigger, polarity);
> -             if (err)
> -                     goto config_release;
> -             psdev->gsi = gsi;
>       }
>  #endif
>  

-- 
Best regards,
Jiqian Chen.