Re: [PATCH 4/5] drm/xe: Guard against NULL GT in xe_guc.c

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 9/26/2025 5:59 PM, Jonathan Cavitt wrote:
> Static analysis reveals the following issue:
> xe_device_get_gt is theoretically able to return NULL in some cases, but
> several use cases don't check the return value before performing a
> dereference, resulting in a NULL pointer dereference.
> 
> Use xe_root_mmio_gt instead of xe_device_get_gt to prevent this in
> xe_guc.c
> 
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index d5adbbb013ec..0bf1402c61a0 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -466,7 +466,7 @@ static int guc_g2g_alloc(struct xe_guc *guc)
>  		return 0;
>  
>  	if (gt->info.id != 0) {
> -		struct xe_gt *root_gt = xe_device_get_gt(xe, 0);
> +		struct xe_gt *root_gt = xe_root_mmio_gt(xe);

while this looks ok today, I'm not sure how this will work after [1]

maybe we should check and abort here? + @Matt

[1] https://patchwork.freedesktop.org/series/154739/

>  		struct xe_guc *root_guc = &root_gt->uc.guc;
>  		struct xe_bo *bo;
>