[PATCH v5] drm/xe/guc: Add devm release action to safely tear down CT

[Matthew Brost]

On Wed, Aug 13, 2025 at 03:42:25PM +0530, Satyanarayana K V P wrote:
> When a buffer object (BO) is allocated with the XE_BO_FLAG_GGTT_INVALIDATE
> flag, the driver initiates TLB invalidation requests via the CTB mechanism
> while releasing the BO. However a premature release of the CTB BO can lead
> to system crashes, as observed in:
> 
> Oops: Oops: 0000 [#1] SMP NOPTI
> RIP: 0010:h2g_write+0x2f3/0x7c0 [xe]
> Call Trace:
>  guc_ct_send_locked+0x8b/0x670 [xe]
>  xe_guc_ct_send_locked+0x19/0x60 [xe]
>  send_tlb_invalidation+0xb4/0x460 [xe]
>  xe_gt_tlb_invalidation_ggtt+0x15e/0x2e0 [xe]
>  ggtt_invalidate_gt_tlb.part.0+0x16/0x90 [xe]
>  ggtt_node_remove+0x110/0x140 [xe]
>  xe_ggtt_node_remove+0x40/0xa0 [xe]
>  xe_ggtt_remove_bo+0x87/0x250 [xe]
> 
> Introduce a devm-managed release action during xe_guc_ct_init() to ensure
> proper CTB disablement before resource deallocation, preventing the
> use-after-free scenario.
> 
> Signed-off-by: Satyanarayana K V P <satyanarayana.k.v.p at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Matthew Brost <matthew.brost at intel.com>

Reviewed-by: Matthew Brost <matthew.brost at intel.com>

> Cc: Matthew Auld <matthew.auld at intel.com>
> Cc: Summers Stuart <stuart.summers at intel.com>
> 
> ---
> V4 -> V5:
> - Updated commit message.
> - Fixed similar crash while releasing resources on DGPU after reallocating
> CTB to VRAM from SMEM.
> 
> V3 -> V4:
> - Added new devm release function action_disable_ct()
> 
> V2 -> V3:
> - Moved GGTT validity check to xe_ggtt_invalidate(). (Michal Wajdeczko)
> 
> V1 -> V2:
> - An additional check for validity of GGTT is added in
> xe_gt_tlb_invalidation_ggtt() instead of removing XE_BO_FLAG_GGTT_INVALIDATE
> from memirq_alloc_pages(), __xe_sa_bo_manager_init() and xe_guc_ct_init().
> (Summers Stuart)
> ---
>  drivers/gpu/drm/xe/xe_guc.c    |  5 ++++-
>  drivers/gpu/drm/xe/xe_guc_ct.c | 14 +++++++++++++-
>  drivers/gpu/drm/xe/xe_guc_ct.h |  2 ++
>  3 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index 433abc787f7b..a6e46272c0ef 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -705,7 +705,10 @@ static int xe_guc_realloc_post_hwconfig(struct xe_guc *guc)
>  	if (ret)
>  		return ret;
>  
> -	return 0;
> +	ret = devm_add_action_or_reset(xe->drm.dev, xe_guc_action_disable_ct,
> +				       &guc->ct);
> +
> +	return ret;
>  }
>  
>  static int vf_guc_init_noalloc(struct xe_guc *guc)
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index 3f4e6a46ff16..fe2410091bfc 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -39,6 +39,8 @@ static void receive_g2h(struct xe_guc_ct *ct);
>  static void g2h_worker_func(struct work_struct *w);
>  static void safe_mode_worker_func(struct work_struct *w);
>  static void ct_exit_safe_mode(struct xe_guc_ct *ct);
> +static void guc_ct_change_state(struct xe_guc_ct *ct,
> +				enum xe_guc_ct_state state);
>  
>  #if IS_ENABLED(CONFIG_DRM_XE_DEBUG)
>  enum {
> @@ -252,12 +254,20 @@ int xe_guc_ct_init_noalloc(struct xe_guc_ct *ct)
>  }
>  ALLOW_ERROR_INJECTION(xe_guc_ct_init_noalloc, ERRNO); /* See xe_pci_probe() */
>  
> +void xe_guc_action_disable_ct(void *arg)
> +{
> +	struct xe_guc_ct *ct = arg;
> +
> +	guc_ct_change_state(ct, XE_GUC_CT_STATE_DISABLED);
> +}
> +
>  int xe_guc_ct_init(struct xe_guc_ct *ct)
>  {
>  	struct xe_device *xe = ct_to_xe(ct);
>  	struct xe_gt *gt = ct_to_gt(ct);
>  	struct xe_tile *tile = gt_to_tile(gt);
>  	struct xe_bo *bo;
> +	int err = 0;
>  
>  	bo = xe_managed_bo_create_pin_map(xe, tile, guc_ct_size(),
>  					  XE_BO_FLAG_SYSTEM |
> @@ -268,7 +278,9 @@ int xe_guc_ct_init(struct xe_guc_ct *ct)
>  		return PTR_ERR(bo);
>  
>  	ct->bo = bo;
> -	return 0;
> +
> +	err = devm_add_action_or_reset(xe->drm.dev, xe_guc_action_disable_ct, ct);
> +	return err;
>  }
>  ALLOW_ERROR_INJECTION(xe_guc_ct_init, ERRNO); /* See xe_pci_probe() */
>  
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
> index 18d4225e6502..b9f06ec0db52 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.h
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.h
> @@ -73,4 +73,6 @@ xe_guc_ct_send_block_no_fail(struct xe_guc_ct *ct, const u32 *action, u32 len)
>  
>  long xe_guc_ct_queue_proc_time_jiffies(struct xe_guc_ct *ct);
>  
> +void xe_guc_action_disable_ct(void *arg);
> +
>  #endif
> -- 
> 2.43.0
>