On 12/16/2016 12:45 PM, Chris Wilson wrote:
On Fri, Dec 16, 2016 at 12:20:05PM -0800, Michel Thierry wrote:
From: Arun Siluvery <arun.siluvery@xxxxxxxxxxxxxxx>
This change implements support for per-engine reset as an initial, less
intrusive hang recovery option to be attempted before falling back to the
legacy full GPU reset recovery mode if necessary. This is only supported
from Gen8 onwards.
Hangchecker determines which engines are hung and invokes error handler to
recover from it. Error handler schedules recovery for each of those engines
that are hung. The recovery procedure is as follows,
- identifies the request that caused the hang and it is dropped
- force engine to idle: this is done by issuing a reset request
- reset and re-init engine
- restart submissions to the engine
If engine reset fails then we fall back to heavy weight full gpu reset
which resets all engines and reinitiazes complete state of HW and SW.
v2: Rebase.
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Signed-off-by: Tomas Elf <tomas.elf@xxxxxxxxx>
Signed-off-by: Arun Siluvery <arun.siluvery@xxxxxxxxxxxxxxx>
Signed-off-by: Michel Thierry <michel.thierry@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.c | 56 +++++++++++++++++++++++++++++++++++--
drivers/gpu/drm/i915/i915_drv.h | 3 ++
drivers/gpu/drm/i915/i915_gem.c | 2 +-
drivers/gpu/drm/i915/intel_lrc.c | 12 ++++++++
drivers/gpu/drm/i915/intel_lrc.h | 1 +
drivers/gpu/drm/i915/intel_uncore.c | 41 ++++++++++++++++++++++++---
6 files changed, 108 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index e5688edd62cd..a034793bc246 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1830,18 +1830,70 @@ void i915_reset(struct drm_i915_private *dev_priv)
*
* Reset a specific GPU engine. Useful if a hang is detected.
* Returns zero on successful reset or otherwise an error code.
+ *
+ * Procedure is fairly simple:
+ * - identifies the request that caused the hang and it is dropped
+ * - force engine to idle: this is done by issuing a reset request
+ * - reset engine
+ * - restart submissions to the engine
*/
int i915_reset_engine(struct intel_engine_cs *engine)
What's the serialisation between potential callers of
i915_reset_engine()?
I haven't seen simultaneous calls happening yet, would a
reset_engine-specific mutex be enough?
{
int ret;
struct drm_i915_private *dev_priv = engine->i915;
- /* FIXME: replace me with engine reset sequence */
- ret = -ENODEV;
+ /*
+ * We need to first idle the engine by issuing a reset request,
+ * then perform soft reset and re-initialize hw state, for all of
+ * this GT power need to be awake so ensure it does throughout the
+ * process
+ */
+ intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
+
+ /*
+ * the request that caused the hang is stuck on elsp, identify the
+ * active request and drop it, adjust head to skip the offending
+ * request to resume executing remaining requests in the queue.
+ */
+ i915_gem_reset_engine(engine);
Must freeze the engine and irqs first, before calling
i915_gem_reset_engine() (i.e. something like disable_engines_irq,
cancelling tasklet)
Will do.
Eeek note that the current i915_gem_reset_engine() is lacking a
spinlock.
The new mutex (for i915_reset_engine) should cover this.
+
+ ret = intel_engine_reset_begin(engine);
+ if (ret) {
+ DRM_ERROR("Failed to disable %s\n", engine->name);
+ goto error;
+ }
+
+ ret = intel_gpu_reset(dev_priv, intel_engine_flag(engine));
+ if (ret) {
+ DRM_ERROR("Failed to reset %s, ret=%d\n", engine->name, ret);
+ intel_engine_reset_cancel(engine);
+ goto error;
+ }
+
+ ret = engine->init_hw(engine);
+ if (ret)
+ goto error;
+ intel_engine_reset_cancel(engine);
+ intel_execlists_restart_submission(engine);
engine->init_hw(engine) *is* intel_execlists_restart_submission.
I'll make these changes,
Thanks.
+
+ intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
+ return 0;
+
+error:
/* use full gpu reset to recover on error */
set_bit(I915_RESET_IN_PROGRESS, &dev_priv->gpu_error.flags);
+ /* Engine reset is performed without taking struct_mutex, since it
+ * failed we now fallback to full gpu reset. Wakeup any waiters
+ * which should now see the reset_in_progress and release
+ * struct_mutex for us to continue recovery.
+ */
+ rcu_read_lock();
+ intel_engine_wakeup(engine);
+ rcu_read_unlock();
+
+ intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
return ret;
}
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