[Intel-gfx] [PATCH v3 1/6] drm/i915: Add engine reset count in get-reset-stats ioctl

[Carlos Santa]

From: Michel Thierry <michel.thierry at intel.com>

Users/tests relying on the total reset count will start seeing a smaller
number since most of the hangs can be handled by engine reset.
Note that if reset engine x, context a running on engine y will be unaware
and unaffected.

To start the discussion, include just a total engine reset count. If it
is deemed useful, it can be extended to report each engine separately.

Our igt's gem_reset_stats test will need changes to ignore the pad field,
since it can now return reset_engine_count.

v2: s/engine_reset/reset_engine/, use union in uapi to not break compatibility.
v3: Keep rejecting attempts to use pad as input (Antonio)
v4: Rebased.
v5: Rebased.

Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
Cc: Antonio Argenziano <antonio.argenziano at intel.com>
Cc: Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Signed-off-by: Michel Thierry <michel.thierry at intel.com>
Signed-off-by: Carlos Santa <carlos.santa at intel.com>
---
 drivers/gpu/drm/i915/i915_gem_context.c | 12 ++++++++++--
 include/uapi/drm/i915_drm.h             |  6 +++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 459f8eae1c39..cbfe8f2eb3f2 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -1889,6 +1889,8 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev,
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct drm_i915_reset_stats *args = data;
 	struct i915_gem_context *ctx;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
 	int ret;
 
 	if (args->flags || args->pad)
@@ -1907,10 +1909,16 @@ int i915_gem_context_reset_stats_ioctl(struct drm_device *dev,
 	 * we should wrap the hangstats with a seqlock.
 	 */
 
-	if (capable(CAP_SYS_ADMIN))
+	if (capable(CAP_SYS_ADMIN)) {
 		args->reset_count = i915_reset_count(&dev_priv->gpu_error);
-	else
+		for_each_engine(engine, dev_priv, id)
+			args->reset_engine_count +=
+				i915_reset_engine_count(&dev_priv->gpu_error,
+							engine);
+	} else {
 		args->reset_count = 0;
+		args->reset_engine_count = 0;
+	}
 
 	args->batch_active = atomic_read(&ctx->guilty_count);
 	args->batch_pending = atomic_read(&ctx->active_count);
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index cc03ef9f885f..3f2c89740b0e 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1642,7 +1642,11 @@ struct drm_i915_reset_stats {
 	/* Number of batches lost pending for execution, for this context */
 	__u32 batch_pending;
 
-	__u32 pad;
+	union {
+		__u32 pad;
+		/* Engine resets since boot/module reload, for all contexts */
+		__u32 reset_engine_count;
+	};
 };
 
 struct drm_i915_gem_userptr {
-- 
2.17.1