Re: [PATCH v3 4/7] drm/xe: Guard against NULL GT in xe_sriov_vf.c

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

On 10/14/2025 6:48 PM, Jonathan Cavitt wrote:
> Static analysis reveals the following issue:
> xe_device_lookup_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.

SRIOV PF/VF can't operate without primary GT, so whatever helper we will
use to get GT we know that such GT must be there (not NULL)

in other words, fix the tool (mark the bug as false-positive in this case)

> 
> Use xe_device_get_gt in places where this is a relevant issue.
> 
> v2:
>  - Use xe_assert in vf_post_migration_recovery (Michal)
> v3:
>  - Rebase
>  - Use xe_device_get_gt
> 
> Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_sriov_vf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.c b/drivers/gpu/drm/xe/xe_sriov_vf.c
> index 189b307901a3..911d5720917b 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_vf.c
> @@ -166,7 +166,7 @@ static void vf_migration_init_early(struct xe_device *xe)
>  	if (!IS_DGFX(xe)) {
>  		struct xe_uc_fw_version guc_version;
>  
> -		xe_gt_sriov_vf_guc_versions(xe_device_lookup_gt(xe, 0), NULL, &guc_version);
> +		xe_gt_sriov_vf_guc_versions(xe_device_get_gt(xe, 0), NULL, &guc_version);

btw, changing the same line twice in one series looks weird

>  		if (MAKE_GUC_VER_STRUCT(guc_version) < MAKE_GUC_VER(1, 23, 0))
>  			return vf_disable_migration(xe,
>  						    "CCS migration requires GuC ABI >= 1.23 but only %u.%u found",