Commit e5152723 authored by Badal Nilawar's avatar Badal Nilawar Committed by Matthew Brost
Browse files

drm/xe/guc/ct: Flush g2h worker in case of g2h response timeout 

In case if g2h worker doesn't get opportunity to within specified
timeout delay then flush the g2h worker explicitly.

v2:
  - Describe change in the comment and add TODO (Matt B/John H)
  - Add xe_gt_warn on fence done after G2H flush (John H)
v3:
  - Updated the comment with root cause
  - Clean up xe_gt_warn message (John H)

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/issues/1620
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/issues/2902


Signed-off-by: default avatarBadal Nilawar <badal.nilawar@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Reviewed-by: default avatarHimal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Acked-by: default avatarMatthew Brost <matthew.brost@intel.com>
Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241017111410.2553784-2-badal.nilawar@intel.com
parent 76eb09c8

drivers/gpu/drm/xe/xe_guc_ct.c

+18 −0
Original line number Diff line number Diff line
@@ -1018,6 +1018,24 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len, 


	ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ);



	/*

	 * Occasionally it is seen that the G2H worker starts running after a delay of more than

	 * a second even after being queued and activated by the Linux workqueue subsystem. This

	 * leads to G2H timeout error. The root cause of issue lies with scheduling latency of

	 * Lunarlake Hybrid CPU. Issue dissappears if we disable Lunarlake atom cores from BIOS

	 * and this is beyond xe kmd.

	 *

	 * TODO: Drop this change once workqueue scheduling delay issue is fixed on LNL Hybrid CPU.

	 */

	if (!ret) {

		flush_work(&ct->g2h_worker);

		if (g2h_fence.done) {

			xe_gt_warn(gt, "G2H fence %u, action %04x, done\n",

				   g2h_fence.seqno, action[0]);

			ret = 1;

		}

	}



	/*

	 * Ensure we serialize with completion side to prevent UAF with fence going out of scope on

	 * the stack, since we have no clue if it will fire after the timeout before we can erase