[PATCH 20/46] drm/i915/guc: Add hang check to GuC submit engine

[Matthew Brost]

The heartbeat uses a single instance of a GuC submit engine (GSE) to do
the hang check. As such if a different GSE's state machine hangs, the
heartbeat cannot detect this hang. Add timer to each GSE which in turn
can disable all submissions if it is hung.

Cc: John Harrison <john.c.harri...@intel.com>
Signed-off-by: Matthew Brost <matthew.br...@intel.com>
---
 .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 36 +++++++++++++++++++
 .../i915/gt/uc/intel_guc_submission_types.h   |  3 ++
 2 files changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c 
b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index afb9b4bb8971..2d8296bcc583 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -105,15 +105,21 @@ static bool tasklet_blocked(struct guc_submit_engine *gse)
        return test_bit(GSE_STATE_TASKLET_BLOCKED, &gse->flags);
 }
 
+/* 2 seconds seems like a reasonable timeout waiting for a G2H */
+#define MAX_TASKLET_BLOCKED_NS 2000000000
 static void set_tasklet_blocked(struct guc_submit_engine *gse)
 {
        lockdep_assert_held(&gse->sched_engine.lock);
+       hrtimer_start_range_ns(&gse->hang_timer,
+                              ns_to_ktime(MAX_TASKLET_BLOCKED_NS), 0,
+                              HRTIMER_MODE_REL_PINNED);
        set_bit(GSE_STATE_TASKLET_BLOCKED, &gse->flags);
 }
 
 static void __clr_tasklet_blocked(struct guc_submit_engine *gse)
 {
        lockdep_assert_held(&gse->sched_engine.lock);
+       hrtimer_cancel(&gse->hang_timer);
        clear_bit(GSE_STATE_TASKLET_BLOCKED, &gse->flags);
 }
 
@@ -1028,6 +1034,7 @@ static void disable_submission(struct intel_guc *guc)
                if (__tasklet_is_enabled(&sched_engine->tasklet)) {
                        GEM_BUG_ON(!guc->ct.enabled);
                        __tasklet_disable_sync_once(&sched_engine->tasklet);
+                       hrtimer_try_to_cancel(&guc->gse[i]->hang_timer);
                        sched_engine->tasklet.callback = NULL;
                }
        }
@@ -3750,6 +3757,33 @@ static void guc_sched_engine_destroy(struct kref *kref)
        kfree(gse);
 }
 
+static enum hrtimer_restart gse_hang(struct hrtimer *hrtimer)
+{
+       struct guc_submit_engine *gse =
+               container_of(hrtimer, struct guc_submit_engine, hang_timer);
+       struct intel_guc *guc = gse->sched_engine.private_data;
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+       if (guc->gse_hang_expected)
+               drm_dbg(&guc_to_gt(guc)->i915->drm,
+                       "GSE[%i] hung, disabling submission", gse->id);
+       else
+               drm_err(&guc_to_gt(guc)->i915->drm,
+                       "GSE[%i] hung, disabling submission", gse->id);
+#else
+       drm_err(&guc_to_gt(guc)->i915->drm,
+               "GSE[%i] hung, disabling submission", gse->id);
+#endif
+
+       /*
+        * Tasklet not making forward progress, disable submission which in turn
+        * will kick in the heartbeat to do a full GPU reset.
+        */
+       disable_submission(guc);
+
+       return HRTIMER_NORESTART;
+}
+
 static void guc_submit_engine_init(struct intel_guc *guc,
                                   struct guc_submit_engine *gse,
                                   int id)
@@ -3767,6 +3801,8 @@ static void guc_submit_engine_init(struct intel_guc *guc,
        sched_engine->retire_inflight_request_prio =
                guc_retire_inflight_request_prio;
        sched_engine->private_data = guc;
+       hrtimer_init(&gse->hang_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+       gse->hang_timer.function = gse_hang;
        gse->id = id;
 }
 
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission_types.h 
b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission_types.h
index a5933e07bdd2..eae2e9725ede 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission_types.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission_types.h
@@ -6,6 +6,8 @@
 #ifndef _INTEL_GUC_SUBMISSION_TYPES_H_
 #define _INTEL_GUC_SUBMISSION_TYPES_H_
 
+#include <linux/xarray.h>
+
 #include "gt/intel_engine_types.h"
 #include "gt/intel_context_types.h"
 #include "i915_scheduler_types.h"
@@ -41,6 +43,7 @@ struct guc_submit_engine {
        unsigned long flags;
        int total_num_rq_with_no_guc_id;
        atomic_t num_guc_ids_not_ready;
+       struct hrtimer hang_timer;
        int id;
 
        /*
-- 
2.28.0