Re: [PATCH] libxl+hvmloader: extend IGD check part 2

[Anthony PERARD <anthony@xxxxxxxxxxxxxx>]

On Tue, Apr 08, 2025 at 03:23:13PM +0200, Marek Marczykowski-Górecki wrote:
> Consider also "Display controller" an IGD, not only "VGA compatible
> controller" in few more places.
> 
> Fixes: 4191619e0893 ("libxl: extend IGD check")
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
> ---
> Do you prefer this to be split into two patches (libxl, hvmloader)?
> 
>  tools/firmware/hvmloader/pci.c | 1 +
>  tools/libs/light/libxl_pci.c   | 3 ++-
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/firmware/hvmloader/pci.c b/tools/firmware/hvmloader/pci.c
> index c3c61ca060a6..1ee97a5b4b20 100644
> --- a/tools/firmware/hvmloader/pci.c
> +++ b/tools/firmware/hvmloader/pci.c
> @@ -173,6 +173,7 @@ void pci_setup(void)
>          switch ( class )
>          {
>          case 0x0300:
> +        case 0x0380:
>              /* If emulated VGA is found, preserve it as primary VGA. */
>              if ( (vendor_id == 0x1234) && (device_id == 0x1111) )
>              {
> diff --git a/tools/libs/light/libxl_pci.c b/tools/libs/light/libxl_pci.c
> index 1647fd6f4756..db1299832cce 100644
> --- a/tools/libs/light/libxl_pci.c
> +++ b/tools/libs/light/libxl_pci.c
> @@ -2575,7 +2575,8 @@ int libxl__grant_vga_iomem_permission(libxl__gc *gc, 
> const uint32_t domid,
>  
>          if (sysfs_dev_get_class(gc, pci, &pci_device_class))
>              continue;
> -        if (pci_device_class != 0x030000) /* VGA class */
> +        if (pci_device_class != 0x030000 && /* VGA class */
> +                pci_device_class != 0x038000) /* Display class */

According to some not too random document on internet [1][2], the whole
0x03 would be the display class, with 0x0380 been other display
controller. So it might be better to change the new comment to "Other
display controller".

[1] 
https://pcisig.com/sites/default/files/files/PCI_Code-ID_r_1_12__v9_Jan_2020.pdf
[2] https://wiki.osdev.org/PCI#Class_Codes

Otherwise, change looks fine to me:
Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>

Thanks,

-- 
Anthony PERARD