[Intel-gfx] [PATCH 6/7] drm/i915: Pull all the reset functionality together into i915_reset.c

Daniel Vetter daniel at ffwll.ch
Wed Jul 11 09:17:09 UTC 2018


On Wed, Jul 11, 2018 at 08:36:07AM +0100, Chris Wilson wrote:
> Currently the code to reset the GPU and our state is spread widely
> across a few files. Pull the logic together into a common file.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Hm when reading the fence code I'd suggested more to move the reset/init
code for a given topic (like fence_reg) into one place. Imo that makes
reviewing changes to a specific thing easier because it's all in one file.

Ofc it makes it harder to review large-scale flows like suspend/resume and
gpu reset, but I think the only thing that can safe us there is lots and
lots of runtime consistency checks for each component (lockdep,
GEM_BUG_ON). Reviewing those is doable, and for the big picture
CI+regrets.

tldr; not sure this is the best organization we can do.
-Daniel

> ---
>  drivers/gpu/drm/i915/Makefile                 |    3 +-
>  drivers/gpu/drm/i915/i915_debugfs.c           |    2 +
>  drivers/gpu/drm/i915/i915_drv.c               |  207 +--
>  drivers/gpu/drm/i915/i915_drv.h               |   31 +-
>  drivers/gpu/drm/i915/i915_gem.c               |  465 +-----
>  drivers/gpu/drm/i915/i915_irq.c               |  220 ---
>  drivers/gpu/drm/i915/i915_request.c           |    1 +
>  drivers/gpu/drm/i915/i915_reset.c             | 1271 +++++++++++++++++
>  drivers/gpu/drm/i915/i915_reset.h             |   37 +
>  drivers/gpu/drm/i915/intel_display.c          |   15 +-
>  drivers/gpu/drm/i915/intel_guc.h              |    3 +
>  drivers/gpu/drm/i915/intel_hangcheck.c        |    1 +
>  drivers/gpu/drm/i915/intel_uc.c               |    1 +
>  drivers/gpu/drm/i915/intel_uncore.c           |  415 ------
>  .../drm/i915/selftests/intel_workarounds.c    |    1 +
>  15 files changed, 1342 insertions(+), 1331 deletions(-)
>  create mode 100644 drivers/gpu/drm/i915/i915_reset.c
>  create mode 100644 drivers/gpu/drm/i915/i915_reset.h
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 5794f102f9b8..d09799e79893 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -40,7 +40,8 @@ i915-y := i915_drv.o \
>  	  i915_mm.o \
>  	  i915_params.o \
>  	  i915_pci.o \
> -          i915_suspend.o \
> +	  i915_reset.o \
> +	  i915_suspend.o \
>  	  i915_syncmap.o \
>  	  i915_sw_fence.o \
>  	  i915_sysfs.o \
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index e2ba298a5d88..a0f519c44410 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -32,6 +32,8 @@
>  #include "intel_drv.h"
>  #include "intel_guc_submission.h"
>  
> +#include "i915_reset.h"
> +
>  static inline struct drm_i915_private *node_to_i915(struct drm_info_node *node)
>  {
>  	return to_i915(node->minor->dev);
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 97a2054c38d4..fa3b4144a7fa 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -49,6 +49,7 @@
>  #include "i915_drv.h"
>  #include "i915_trace.h"
>  #include "i915_pmu.h"
> +#include "i915_reset.h"
>  #include "i915_query.h"
>  #include "i915_vgpu.h"
>  #include "intel_drv.h"
> @@ -1878,212 +1879,6 @@ static int i915_resume_switcheroo(struct drm_device *dev)
>  	return i915_drm_resume(dev);
>  }
>  
> -/**
> - * i915_reset - reset chip after a hang
> - * @i915: #drm_i915_private to reset
> - * @stalled_mask: mask of the stalled engines with the guilty requests
> - * @reason: user error message for why we are resetting
> - *
> - * Reset the chip.  Useful if a hang is detected. Marks the device as wedged
> - * on failure.
> - *
> - * Caller must hold the struct_mutex.
> - *
> - * Procedure is fairly simple:
> - *   - reset the chip using the reset reg
> - *   - re-init context state
> - *   - re-init hardware status page
> - *   - re-init ring buffer
> - *   - re-init interrupt state
> - *   - re-init display
> - */
> -void i915_reset(struct drm_i915_private *i915,
> -		unsigned int stalled_mask,
> -		const char *reason)
> -{
> -	struct i915_gpu_error *error = &i915->gpu_error;
> -	int ret;
> -	int i;
> -
> -	GEM_TRACE("flags=%lx\n", error->flags);
> -
> -	might_sleep();
> -	lockdep_assert_held(&i915->drm.struct_mutex);
> -	GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, &error->flags));
> -
> -	if (!test_bit(I915_RESET_HANDOFF, &error->flags))
> -		return;
> -
> -	/* Clear any previous failed attempts at recovery. Time to try again. */
> -	if (!i915_gem_unset_wedged(i915))
> -		goto wakeup;
> -
> -	if (reason)
> -		dev_notice(i915->drm.dev, "Resetting chip for %s\n", reason);
> -	error->reset_count++;
> -
> -	disable_irq(i915->drm.irq);
> -	ret = i915_gem_reset_prepare(i915);
> -	if (ret) {
> -		dev_err(i915->drm.dev, "GPU recovery failed\n");
> -		goto taint;
> -	}
> -
> -	if (!intel_has_gpu_reset(i915)) {
> -		if (i915_modparams.reset)
> -			dev_err(i915->drm.dev, "GPU reset not supported\n");
> -		else
> -			DRM_DEBUG_DRIVER("GPU reset disabled\n");
> -		goto error;
> -	}
> -
> -	for (i = 0; i < 3; i++) {
> -		ret = intel_gpu_reset(i915, ALL_ENGINES);
> -		if (ret == 0)
> -			break;
> -
> -		msleep(100);
> -	}
> -	if (ret) {
> -		dev_err(i915->drm.dev, "Failed to reset chip\n");
> -		goto taint;
> -	}
> -
> -	/* Ok, now get things going again... */
> -
> -	/*
> -	 * Everything depends on having the GTT running, so we need to start
> -	 * there.
> -	 */
> -	ret = i915_ggtt_enable_hw(i915);
> -	if (ret) {
> -		DRM_ERROR("Failed to re-enable GGTT following reset (%d)\n",
> -			  ret);
> -		goto error;
> -	}
> -
> -	i915_gem_reset(i915, stalled_mask);
> -	intel_overlay_reset(i915);
> -
> -	/*
> -	 * Next we need to restore the context, but we don't use those
> -	 * yet either...
> -	 *
> -	 * Ring buffer needs to be re-initialized in the KMS case, or if X
> -	 * was running at the time of the reset (i.e. we weren't VT
> -	 * switched away).
> -	 */
> -	ret = i915_gem_init_hw(i915);
> -	if (ret) {
> -		DRM_ERROR("Failed to initialise HW following reset (%d)\n",
> -			  ret);
> -		goto error;
> -	}
> -
> -	i915_queue_hangcheck(i915);
> -
> -finish:
> -	i915_gem_reset_finish(i915);
> -	enable_irq(i915->drm.irq);
> -
> -wakeup:
> -	clear_bit(I915_RESET_HANDOFF, &error->flags);
> -	wake_up_bit(&error->flags, I915_RESET_HANDOFF);
> -	return;
> -
> -taint:
> -	/*
> -	 * History tells us that if we cannot reset the GPU now, we
> -	 * never will. This then impacts everything that is run
> -	 * subsequently. On failing the reset, we mark the driver
> -	 * as wedged, preventing further execution on the GPU.
> -	 * We also want to go one step further and add a taint to the
> -	 * kernel so that any subsequent faults can be traced back to
> -	 * this failure. This is important for CI, where if the
> -	 * GPU/driver fails we would like to reboot and restart testing
> -	 * rather than continue on into oblivion. For everyone else,
> -	 * the system should still plod along, but they have been warned!
> -	 */
> -	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
> -error:
> -	i915_gem_set_wedged(i915);
> -	i915_retire_requests(i915);
> -	goto finish;
> -}
> -
> -static inline int intel_gt_reset_engine(struct drm_i915_private *dev_priv,
> -					struct intel_engine_cs *engine)
> -{
> -	return intel_gpu_reset(dev_priv, intel_engine_flag(engine));
> -}
> -
> -/**
> - * i915_reset_engine - reset GPU engine to recover from a hang
> - * @engine: engine to reset
> - * @msg: reason for GPU reset; or NULL for no dev_notice()
> - *
> - * Reset a specific GPU engine. Useful if a hang is detected.
> - * Returns zero on successful reset or otherwise an error code.
> - *
> - * Procedure is:
> - *  - identifies the request that caused the hang and it is dropped
> - *  - reset engine (which will force the engine to idle)
> - *  - re-init/configure engine
> - */
> -int i915_reset_engine(struct intel_engine_cs *engine, const char *msg)
> -{
> -	struct i915_gpu_error *error = &engine->i915->gpu_error;
> -	struct i915_request *active_request;
> -	int ret;
> -
> -	GEM_TRACE("%s flags=%lx\n", engine->name, error->flags);
> -	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &error->flags));
> -
> -	active_request = i915_gem_reset_prepare_engine(engine);
> -	if (IS_ERR_OR_NULL(active_request)) {
> -		/* Either the previous reset failed, or we pardon the reset. */
> -		ret = PTR_ERR(active_request);
> -		goto out;
> -	}
> -
> -	if (msg)
> -		dev_notice(engine->i915->drm.dev,
> -			   "Resetting %s for %s\n", engine->name, msg);
> -	error->reset_engine_count[engine->id]++;
> -
> -	if (!engine->i915->guc.execbuf_client)
> -		ret = intel_gt_reset_engine(engine->i915, engine);
> -	else
> -		ret = intel_guc_reset_engine(&engine->i915->guc, engine);
> -	if (ret) {
> -		/* If we fail here, we expect to fallback to a global reset */
> -		DRM_DEBUG_DRIVER("%sFailed to reset %s, ret=%d\n",
> -				 engine->i915->guc.execbuf_client ? "GuC " : "",
> -				 engine->name, ret);
> -		goto out;
> -	}
> -
> -	/*
> -	 * The request that caused the hang is stuck on elsp, we know the
> -	 * active request and can drop it, adjust head to skip the offending
> -	 * request to resume executing remaining requests in the queue.
> -	 */
> -	i915_gem_reset_engine(engine, active_request, true);
> -
> -	/*
> -	 * The engine and its registers (and workarounds in case of render)
> -	 * have been reset to their default values. Follow the init_ring
> -	 * process to program RING_MODE, HWSP and re-enable submission.
> -	 */
> -	ret = engine->init_hw(engine);
> -	if (ret)
> -		goto out;
> -
> -out:
> -	i915_gem_reset_finish_engine(engine);
> -	return ret;
> -}
> -
>  static int i915_pm_prepare(struct device *kdev)
>  {
>  	struct pci_dev *pdev = to_pci_dev(kdev);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 43f545add21c..84b1073eacd8 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -2700,19 +2700,7 @@ extern const struct dev_pm_ops i915_pm_ops;
>  extern int i915_driver_load(struct pci_dev *pdev,
>  			    const struct pci_device_id *ent);
>  extern void i915_driver_unload(struct drm_device *dev);
> -extern int intel_gpu_reset(struct drm_i915_private *dev_priv, u32 engine_mask);
> -extern bool intel_has_gpu_reset(struct drm_i915_private *dev_priv);
> -
> -extern void i915_reset(struct drm_i915_private *i915,
> -		       unsigned int stalled_mask,
> -		       const char *reason);
> -extern int i915_reset_engine(struct intel_engine_cs *engine,
> -			     const char *reason);
> -
> -extern bool intel_has_reset_engine(struct drm_i915_private *dev_priv);
> -extern int intel_reset_guc(struct drm_i915_private *dev_priv);
> -extern int intel_guc_reset_engine(struct intel_guc *guc,
> -				  struct intel_engine_cs *engine);
> +
>  extern void intel_engine_init_hangcheck(struct intel_engine_cs *engine);
>  extern void intel_hangcheck_init(struct drm_i915_private *dev_priv);
>  extern unsigned long i915_chipset_val(struct drm_i915_private *dev_priv);
> @@ -2757,13 +2745,6 @@ static inline void i915_queue_hangcheck(struct drm_i915_private *dev_priv)
>  			   &dev_priv->gpu_error.hangcheck_work, delay);
>  }
>  
> -__printf(4, 5)
> -void i915_handle_error(struct drm_i915_private *dev_priv,
> -		       u32 engine_mask,
> -		       unsigned long flags,
> -		       const char *fmt, ...);
> -#define I915_ERROR_CAPTURE BIT(0)
> -
>  extern void intel_irq_init(struct drm_i915_private *dev_priv);
>  extern void intel_irq_fini(struct drm_i915_private *dev_priv);
>  int intel_irq_install(struct drm_i915_private *dev_priv);
> @@ -3126,18 +3107,8 @@ static inline u32 i915_reset_engine_count(struct i915_gpu_error *error,
>  	return READ_ONCE(error->reset_engine_count[engine->id]);
>  }
>  
> -struct i915_request *
> -i915_gem_reset_prepare_engine(struct intel_engine_cs *engine);
> -int i915_gem_reset_prepare(struct drm_i915_private *dev_priv);
> -void i915_gem_reset(struct drm_i915_private *dev_priv,
> -		    unsigned int stalled_mask);
> -void i915_gem_reset_finish_engine(struct intel_engine_cs *engine);
> -void i915_gem_reset_finish(struct drm_i915_private *dev_priv);
>  void i915_gem_set_wedged(struct drm_i915_private *dev_priv);
>  bool i915_gem_unset_wedged(struct drm_i915_private *dev_priv);
> -void i915_gem_reset_engine(struct intel_engine_cs *engine,
> -			   struct i915_request *request,
> -			   bool stalled);
>  
>  void i915_gem_init_mmio(struct drm_i915_private *i915);
>  int __must_check i915_gem_init(struct drm_i915_private *dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 8eecd68f9e23..b5822cc36221 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -28,15 +28,6 @@
>  #include <drm/drmP.h>
>  #include <drm/drm_vma_manager.h>
>  #include <drm/i915_drm.h>
> -#include "i915_drv.h"
> -#include "i915_gem_clflush.h"
> -#include "i915_vgpu.h"
> -#include "i915_trace.h"
> -#include "intel_drv.h"
> -#include "intel_frontbuffer.h"
> -#include "intel_mocs.h"
> -#include "intel_workarounds.h"
> -#include "i915_gemfs.h"
>  #include <linux/dma-fence-array.h>
>  #include <linux/kthread.h>
>  #include <linux/reservation.h>
> @@ -47,6 +38,18 @@
>  #include <linux/pci.h>
>  #include <linux/dma-buf.h>
>  
> +#include "i915_drv.h"
> +#include "i915_gem_clflush.h"
> +#include "i915_gemfs.h"
> +#include "i915_reset.h"
> +#include "i915_trace.h"
> +#include "i915_vgpu.h"
> +
> +#include "intel_drv.h"
> +#include "intel_frontbuffer.h"
> +#include "intel_mocs.h"
> +#include "intel_workarounds.h"
> +
>  static void i915_gem_flush_free_objects(struct drm_i915_private *i915);
>  
>  static bool cpu_write_needs_clflush(struct drm_i915_gem_object *obj)
> @@ -2960,61 +2963,6 @@ i915_gem_object_pwrite_gtt(struct drm_i915_gem_object *obj,
>  	return 0;
>  }
>  
> -static void i915_gem_client_mark_guilty(struct drm_i915_file_private *file_priv,
> -					const struct i915_gem_context *ctx)
> -{
> -	unsigned int score;
> -	unsigned long prev_hang;
> -
> -	if (i915_gem_context_is_banned(ctx))
> -		score = I915_CLIENT_SCORE_CONTEXT_BAN;
> -	else
> -		score = 0;
> -
> -	prev_hang = xchg(&file_priv->hang_timestamp, jiffies);
> -	if (time_before(jiffies, prev_hang + I915_CLIENT_FAST_HANG_JIFFIES))
> -		score += I915_CLIENT_SCORE_HANG_FAST;
> -
> -	if (score) {
> -		atomic_add(score, &file_priv->ban_score);
> -
> -		DRM_DEBUG_DRIVER("client %s: gained %u ban score, now %u\n",
> -				 ctx->name, score,
> -				 atomic_read(&file_priv->ban_score));
> -	}
> -}
> -
> -static void i915_gem_context_mark_guilty(struct i915_gem_context *ctx)
> -{
> -	unsigned int score;
> -	bool banned, bannable;
> -
> -	atomic_inc(&ctx->guilty_count);
> -
> -	bannable = i915_gem_context_is_bannable(ctx);
> -	score = atomic_add_return(CONTEXT_SCORE_GUILTY, &ctx->ban_score);
> -	banned = score >= CONTEXT_SCORE_BAN_THRESHOLD;
> -
> -	/* Cool contexts don't accumulate client ban score */
> -	if (!bannable)
> -		return;
> -
> -	if (banned) {
> -		DRM_DEBUG_DRIVER("context %s: guilty %d, score %u, banned\n",
> -				 ctx->name, atomic_read(&ctx->guilty_count),
> -				 score);
> -		i915_gem_context_set_banned(ctx);
> -	}
> -
> -	if (!IS_ERR_OR_NULL(ctx->file_priv))
> -		i915_gem_client_mark_guilty(ctx->file_priv, ctx);
> -}
> -
> -static void i915_gem_context_mark_innocent(struct i915_gem_context *ctx)
> -{
> -	atomic_inc(&ctx->active_count);
> -}
> -
>  struct i915_request *
>  i915_gem_find_active_request(struct intel_engine_cs *engine)
>  {
> @@ -3045,395 +2993,6 @@ i915_gem_find_active_request(struct intel_engine_cs *engine)
>  	return active;
>  }
>  
> -/*
> - * Ensure irq handler finishes, and not run again.
> - * Also return the active request so that we only search for it once.
> - */
> -struct i915_request *
> -i915_gem_reset_prepare_engine(struct intel_engine_cs *engine)
> -{
> -	struct i915_request *request;
> -
> -	/*
> -	 * During the reset sequence, we must prevent the engine from
> -	 * entering RC6. As the context state is undefined until we restart
> -	 * the engine, if it does enter RC6 during the reset, the state
> -	 * written to the powercontext is undefined and so we may lose
> -	 * GPU state upon resume, i.e. fail to restart after a reset.
> -	 */
> -	intel_uncore_forcewake_get(engine->i915, FORCEWAKE_ALL);
> -
> -	request = engine->reset.prepare(engine);
> -	if (request && request->fence.error == -EIO)
> -		request = ERR_PTR(-EIO); /* Previous reset failed! */
> -
> -	return request;
> -}
> -
> -int i915_gem_reset_prepare(struct drm_i915_private *dev_priv)
> -{
> -	struct intel_engine_cs *engine;
> -	struct i915_request *request;
> -	enum intel_engine_id id;
> -	int err = 0;
> -
> -	for_each_engine(engine, dev_priv, id) {
> -		request = i915_gem_reset_prepare_engine(engine);
> -		if (IS_ERR(request)) {
> -			err = PTR_ERR(request);
> -			continue;
> -		}
> -
> -		engine->hangcheck.active_request = request;
> -	}
> -
> -	i915_gem_revoke_fences(dev_priv);
> -	intel_uc_sanitize(dev_priv);
> -
> -	return err;
> -}
> -
> -static void engine_skip_context(struct i915_request *request)
> -{
> -	struct intel_engine_cs *engine = request->engine;
> -	struct i915_gem_context *hung_ctx = request->gem_context;
> -	struct i915_timeline *timeline = request->timeline;
> -	unsigned long flags;
> -
> -	GEM_BUG_ON(timeline == &engine->timeline);
> -
> -	spin_lock_irqsave(&engine->timeline.lock, flags);
> -	spin_lock(&timeline->lock);
> -
> -	list_for_each_entry_continue(request, &engine->timeline.requests, link)
> -		if (request->gem_context == hung_ctx)
> -			i915_request_skip(request, -EIO);
> -
> -	list_for_each_entry(request, &timeline->requests, link)
> -		i915_request_skip(request, -EIO);
> -
> -	spin_unlock(&timeline->lock);
> -	spin_unlock_irqrestore(&engine->timeline.lock, flags);
> -}
> -
> -/* Returns the request if it was guilty of the hang */
> -static struct i915_request *
> -i915_gem_reset_request(struct intel_engine_cs *engine,
> -		       struct i915_request *request,
> -		       bool stalled)
> -{
> -	/* The guilty request will get skipped on a hung engine.
> -	 *
> -	 * Users of client default contexts do not rely on logical
> -	 * state preserved between batches so it is safe to execute
> -	 * queued requests following the hang. Non default contexts
> -	 * rely on preserved state, so skipping a batch loses the
> -	 * evolution of the state and it needs to be considered corrupted.
> -	 * Executing more queued batches on top of corrupted state is
> -	 * risky. But we take the risk by trying to advance through
> -	 * the queued requests in order to make the client behaviour
> -	 * more predictable around resets, by not throwing away random
> -	 * amount of batches it has prepared for execution. Sophisticated
> -	 * clients can use gem_reset_stats_ioctl and dma fence status
> -	 * (exported via sync_file info ioctl on explicit fences) to observe
> -	 * when it loses the context state and should rebuild accordingly.
> -	 *
> -	 * The context ban, and ultimately the client ban, mechanism are safety
> -	 * valves if client submission ends up resulting in nothing more than
> -	 * subsequent hangs.
> -	 */
> -
> -	if (i915_request_completed(request)) {
> -		GEM_TRACE("%s pardoned global=%d (fence %llx:%d), current %d\n",
> -			  engine->name, request->global_seqno,
> -			  request->fence.context, request->fence.seqno,
> -			  intel_engine_get_seqno(engine));
> -		stalled = false;
> -	}
> -
> -	if (stalled) {
> -		i915_gem_context_mark_guilty(request->gem_context);
> -		i915_request_skip(request, -EIO);
> -
> -		/* If this context is now banned, skip all pending requests. */
> -		if (i915_gem_context_is_banned(request->gem_context))
> -			engine_skip_context(request);
> -	} else {
> -		/*
> -		 * Since this is not the hung engine, it may have advanced
> -		 * since the hang declaration. Double check by refinding
> -		 * the active request at the time of the reset.
> -		 */
> -		request = i915_gem_find_active_request(engine);
> -		if (request) {
> -			unsigned long flags;
> -
> -			i915_gem_context_mark_innocent(request->gem_context);
> -			dma_fence_set_error(&request->fence, -EAGAIN);
> -
> -			/* Rewind the engine to replay the incomplete rq */
> -			spin_lock_irqsave(&engine->timeline.lock, flags);
> -			request = list_prev_entry(request, link);
> -			if (&request->link == &engine->timeline.requests)
> -				request = NULL;
> -			spin_unlock_irqrestore(&engine->timeline.lock, flags);
> -		}
> -	}
> -
> -	return request;
> -}
> -
> -void i915_gem_reset_engine(struct intel_engine_cs *engine,
> -			   struct i915_request *request,
> -			   bool stalled)
> -{
> -	/*
> -	 * Make sure this write is visible before we re-enable the interrupt
> -	 * handlers on another CPU, as tasklet_enable() resolves to just
> -	 * a compiler barrier which is insufficient for our purpose here.
> -	 */
> -	smp_store_mb(engine->irq_posted, 0);
> -
> -	if (request)
> -		request = i915_gem_reset_request(engine, request, stalled);
> -
> -	/* Setup the CS to resume from the breadcrumb of the hung request */
> -	engine->reset.reset(engine, request);
> -}
> -
> -void i915_gem_reset(struct drm_i915_private *dev_priv,
> -		    unsigned int stalled_mask)
> -{
> -	struct intel_engine_cs *engine;
> -	enum intel_engine_id id;
> -
> -	lockdep_assert_held(&dev_priv->drm.struct_mutex);
> -
> -	i915_retire_requests(dev_priv);
> -
> -	for_each_engine(engine, dev_priv, id) {
> -		struct intel_context *ce;
> -
> -		i915_gem_reset_engine(engine,
> -				      engine->hangcheck.active_request,
> -				      stalled_mask & ENGINE_MASK(id));
> -		ce = fetch_and_zero(&engine->last_retired_context);
> -		if (ce)
> -			intel_context_unpin(ce);
> -
> -		/*
> -		 * Ostensibily, we always want a context loaded for powersaving,
> -		 * so if the engine is idle after the reset, send a request
> -		 * to load our scratch kernel_context.
> -		 *
> -		 * More mysteriously, if we leave the engine idle after a reset,
> -		 * the next userspace batch may hang, with what appears to be
> -		 * an incoherent read by the CS (presumably stale TLB). An
> -		 * empty request appears sufficient to paper over the glitch.
> -		 */
> -		if (intel_engine_is_idle(engine)) {
> -			struct i915_request *rq;
> -
> -			rq = i915_request_alloc(engine,
> -						dev_priv->kernel_context);
> -			if (!IS_ERR(rq))
> -				i915_request_add(rq);
> -		}
> -	}
> -
> -	i915_gem_restore_fences(dev_priv);
> -}
> -
> -void i915_gem_reset_finish_engine(struct intel_engine_cs *engine)
> -{
> -	engine->reset.finish(engine);
> -
> -	intel_uncore_forcewake_put(engine->i915, FORCEWAKE_ALL);
> -}
> -
> -void i915_gem_reset_finish(struct drm_i915_private *dev_priv)
> -{
> -	struct intel_engine_cs *engine;
> -	enum intel_engine_id id;
> -
> -	lockdep_assert_held(&dev_priv->drm.struct_mutex);
> -
> -	for_each_engine(engine, dev_priv, id) {
> -		engine->hangcheck.active_request = NULL;
> -		i915_gem_reset_finish_engine(engine);
> -	}
> -}
> -
> -static void nop_submit_request(struct i915_request *request)
> -{
> -	GEM_TRACE("%s fence %llx:%d -> -EIO\n",
> -		  request->engine->name,
> -		  request->fence.context, request->fence.seqno);
> -	dma_fence_set_error(&request->fence, -EIO);
> -
> -	i915_request_submit(request);
> -}
> -
> -static void nop_complete_submit_request(struct i915_request *request)
> -{
> -	unsigned long flags;
> -
> -	GEM_TRACE("%s fence %llx:%d -> -EIO\n",
> -		  request->engine->name,
> -		  request->fence.context, request->fence.seqno);
> -	dma_fence_set_error(&request->fence, -EIO);
> -
> -	spin_lock_irqsave(&request->engine->timeline.lock, flags);
> -	__i915_request_submit(request);
> -	intel_engine_init_global_seqno(request->engine, request->global_seqno);
> -	spin_unlock_irqrestore(&request->engine->timeline.lock, flags);
> -}
> -
> -void i915_gem_set_wedged(struct drm_i915_private *i915)
> -{
> -	struct intel_engine_cs *engine;
> -	enum intel_engine_id id;
> -
> -	GEM_TRACE("start\n");
> -
> -	if (GEM_SHOW_DEBUG()) {
> -		struct drm_printer p = drm_debug_printer(__func__);
> -
> -		for_each_engine(engine, i915, id)
> -			intel_engine_dump(engine, &p, "%s\n", engine->name);
> -	}
> -
> -	set_bit(I915_WEDGED, &i915->gpu_error.flags);
> -	smp_mb__after_atomic();
> -
> -	/*
> -	 * First, stop submission to hw, but do not yet complete requests by
> -	 * rolling the global seqno forward (since this would complete requests
> -	 * for which we haven't set the fence error to EIO yet).
> -	 */
> -	for_each_engine(engine, i915, id) {
> -		i915_gem_reset_prepare_engine(engine);
> -
> -		engine->submit_request = nop_submit_request;
> -		engine->schedule = NULL;
> -	}
> -	i915->caps.scheduler = 0;
> -
> -	/* Even if the GPU reset fails, it should still stop the engines */
> -	intel_gpu_reset(i915, ALL_ENGINES);
> -
> -	/*
> -	 * Make sure no one is running the old callback before we proceed with
> -	 * cancelling requests and resetting the completion tracking. Otherwise
> -	 * we might submit a request to the hardware which never completes.
> -	 */
> -	synchronize_rcu();
> -
> -	for_each_engine(engine, i915, id) {
> -		/* Mark all executing requests as skipped */
> -		engine->cancel_requests(engine);
> -
> -		/*
> -		 * Only once we've force-cancelled all in-flight requests can we
> -		 * start to complete all requests.
> -		 */
> -		engine->submit_request = nop_complete_submit_request;
> -	}
> -
> -	/*
> -	 * Make sure no request can slip through without getting completed by
> -	 * either this call here to intel_engine_init_global_seqno, or the one
> -	 * in nop_complete_submit_request.
> -	 */
> -	synchronize_rcu();
> -
> -	for_each_engine(engine, i915, id) {
> -		unsigned long flags;
> -
> -		/*
> -		 * Mark all pending requests as complete so that any concurrent
> -		 * (lockless) lookup doesn't try and wait upon the request as we
> -		 * reset it.
> -		 */
> -		spin_lock_irqsave(&engine->timeline.lock, flags);
> -		intel_engine_init_global_seqno(engine,
> -					       intel_engine_last_submit(engine));
> -		spin_unlock_irqrestore(&engine->timeline.lock, flags);
> -
> -		i915_gem_reset_finish_engine(engine);
> -	}
> -
> -	GEM_TRACE("end\n");
> -
> -	wake_up_all(&i915->gpu_error.reset_queue);
> -}
> -
> -bool i915_gem_unset_wedged(struct drm_i915_private *i915)
> -{
> -	struct i915_timeline *tl;
> -
> -	lockdep_assert_held(&i915->drm.struct_mutex);
> -	if (!test_bit(I915_WEDGED, &i915->gpu_error.flags))
> -		return true;
> -
> -	GEM_TRACE("start\n");
> -
> -	/*
> -	 * Before unwedging, make sure that all pending operations
> -	 * are flushed and errored out - we may have requests waiting upon
> -	 * third party fences. We marked all inflight requests as EIO, and
> -	 * every execbuf since returned EIO, for consistency we want all
> -	 * the currently pending requests to also be marked as EIO, which
> -	 * is done inside our nop_submit_request - and so we must wait.
> -	 *
> -	 * No more can be submitted until we reset the wedged bit.
> -	 */
> -	list_for_each_entry(tl, &i915->gt.timelines, link) {
> -		struct i915_request *rq;
> -
> -		rq = i915_gem_active_peek(&tl->last_request,
> -					  &i915->drm.struct_mutex);
> -		if (!rq)
> -			continue;
> -
> -		/*
> -		 * We can't use our normal waiter as we want to
> -		 * avoid recursively trying to handle the current
> -		 * reset. The basic dma_fence_default_wait() installs
> -		 * a callback for dma_fence_signal(), which is
> -		 * triggered by our nop handler (indirectly, the
> -		 * callback enables the signaler thread which is
> -		 * woken by the nop_submit_request() advancing the seqno
> -		 * and when the seqno passes the fence, the signaler
> -		 * then signals the fence waking us up).
> -		 */
> -		if (dma_fence_default_wait(&rq->fence, true,
> -					   MAX_SCHEDULE_TIMEOUT) < 0)
> -			return false;
> -	}
> -	i915_retire_requests(i915);
> -	GEM_BUG_ON(i915->gt.active_requests);
> -
> -	/*
> -	 * Undo nop_submit_request. We prevent all new i915 requests from
> -	 * being queued (by disallowing execbuf whilst wedged) so having
> -	 * waited for all active requests above, we know the system is idle
> -	 * and do not have to worry about a thread being inside
> -	 * engine->submit_request() as we swap over. So unlike installing
> -	 * the nop_submit_request on reset, we can do this from normal
> -	 * context and do not require stop_machine().
> -	 */
> -	intel_engines_reset_default_submission(i915);
> -	i915_gem_contexts_lost(i915);
> -
> -	GEM_TRACE("end\n");
> -
> -	smp_mb__before_atomic(); /* complete takeover before enabling execbuf */
> -	clear_bit(I915_WEDGED, &i915->gpu_error.flags);
> -
> -	return true;
> -}
> -
>  static void
>  i915_gem_retire_work_handler(struct work_struct *work)
>  {
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 495b9d27990e..76daa31dc2ba 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2928,46 +2928,6 @@ static irqreturn_t gen8_irq_handler(int irq, void *arg)
>  	return IRQ_HANDLED;
>  }
>  
> -struct wedge_me {
> -	struct delayed_work work;
> -	struct drm_i915_private *i915;
> -	const char *name;
> -};
> -
> -static void wedge_me(struct work_struct *work)
> -{
> -	struct wedge_me *w = container_of(work, typeof(*w), work.work);
> -
> -	dev_err(w->i915->drm.dev,
> -		"%s timed out, cancelling all in-flight rendering.\n",
> -		w->name);
> -	i915_gem_set_wedged(w->i915);
> -}
> -
> -static void __init_wedge(struct wedge_me *w,
> -			 struct drm_i915_private *i915,
> -			 long timeout,
> -			 const char *name)
> -{
> -	w->i915 = i915;
> -	w->name = name;
> -
> -	INIT_DELAYED_WORK_ONSTACK(&w->work, wedge_me);
> -	schedule_delayed_work(&w->work, timeout);
> -}
> -
> -static void __fini_wedge(struct wedge_me *w)
> -{
> -	cancel_delayed_work_sync(&w->work);
> -	destroy_delayed_work_on_stack(&w->work);
> -	w->i915 = NULL;
> -}
> -
> -#define i915_wedge_on_timeout(W, DEV, TIMEOUT)				\
> -	for (__init_wedge((W), (DEV), (TIMEOUT), __func__);		\
> -	     (W)->i915;							\
> -	     __fini_wedge((W)))
> -
>  static u32
>  gen11_gt_engine_identity(struct drm_i915_private * const i915,
>  			 const unsigned int bank, const unsigned int bit)
> @@ -3172,186 +3132,6 @@ static irqreturn_t gen11_irq_handler(int irq, void *arg)
>  	return IRQ_HANDLED;
>  }
>  
> -static void i915_reset_device(struct drm_i915_private *dev_priv,
> -			      u32 engine_mask,
> -			      const char *reason)
> -{
> -	struct i915_gpu_error *error = &dev_priv->gpu_error;
> -	struct kobject *kobj = &dev_priv->drm.primary->kdev->kobj;
> -	char *error_event[] = { I915_ERROR_UEVENT "=1", NULL };
> -	char *reset_event[] = { I915_RESET_UEVENT "=1", NULL };
> -	char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL };
> -	struct wedge_me w;
> -
> -	kobject_uevent_env(kobj, KOBJ_CHANGE, error_event);
> -
> -	DRM_DEBUG_DRIVER("resetting chip\n");
> -	kobject_uevent_env(kobj, KOBJ_CHANGE, reset_event);
> -
> -	/* Use a watchdog to ensure that our reset completes */
> -	i915_wedge_on_timeout(&w, dev_priv, 5*HZ) {
> -		intel_prepare_reset(dev_priv);
> -
> -		error->reason = reason;
> -		error->stalled_mask = engine_mask;
> -
> -		/* Signal that locked waiters should reset the GPU */
> -		smp_mb__before_atomic();
> -		set_bit(I915_RESET_HANDOFF, &error->flags);
> -		wake_up_all(&error->wait_queue);
> -
> -		/* Wait for anyone holding the lock to wakeup, without
> -		 * blocking indefinitely on struct_mutex.
> -		 */
> -		do {
> -			if (mutex_trylock(&dev_priv->drm.struct_mutex)) {
> -				i915_reset(dev_priv, engine_mask, reason);
> -				mutex_unlock(&dev_priv->drm.struct_mutex);
> -			}
> -		} while (wait_on_bit_timeout(&error->flags,
> -					     I915_RESET_HANDOFF,
> -					     TASK_UNINTERRUPTIBLE,
> -					     1));
> -
> -		error->stalled_mask = 0;
> -		error->reason = NULL;
> -
> -		intel_finish_reset(dev_priv);
> -	}
> -
> -	if (!test_bit(I915_WEDGED, &error->flags))
> -		kobject_uevent_env(kobj, KOBJ_CHANGE, reset_done_event);
> -}
> -
> -static void i915_clear_error_registers(struct drm_i915_private *dev_priv)
> -{
> -	u32 eir;
> -
> -	if (!IS_GEN2(dev_priv))
> -		I915_WRITE(PGTBL_ER, I915_READ(PGTBL_ER));
> -
> -	if (INTEL_GEN(dev_priv) < 4)
> -		I915_WRITE(IPEIR, I915_READ(IPEIR));
> -	else
> -		I915_WRITE(IPEIR_I965, I915_READ(IPEIR_I965));
> -
> -	I915_WRITE(EIR, I915_READ(EIR));
> -	eir = I915_READ(EIR);
> -	if (eir) {
> -		/*
> -		 * some errors might have become stuck,
> -		 * mask them.
> -		 */
> -		DRM_DEBUG_DRIVER("EIR stuck: 0x%08x, masking\n", eir);
> -		I915_WRITE(EMR, I915_READ(EMR) | eir);
> -		I915_WRITE(IIR, I915_MASTER_ERROR_INTERRUPT);
> -	}
> -}
> -
> -/**
> - * i915_handle_error - handle a gpu error
> - * @dev_priv: i915 device private
> - * @engine_mask: mask representing engines that are hung
> - * @flags: control flags
> - * @fmt: Error message format string
> - *
> - * Do some basic checking of register state at error time and
> - * dump it to the syslog.  Also call i915_capture_error_state() to make
> - * sure we get a record and make it available in debugfs.  Fire a uevent
> - * so userspace knows something bad happened (should trigger collection
> - * of a ring dump etc.).
> - */
> -void i915_handle_error(struct drm_i915_private *dev_priv,
> -		       u32 engine_mask,
> -		       unsigned long flags,
> -		       const char *fmt, ...)
> -{
> -	struct intel_engine_cs *engine;
> -	unsigned int tmp;
> -	char error_msg[80];
> -	char *msg = NULL;
> -
> -	if (fmt) {
> -		va_list args;
> -
> -		va_start(args, fmt);
> -		vscnprintf(error_msg, sizeof(error_msg), fmt, args);
> -		va_end(args);
> -
> -		msg = error_msg;
> -	}
> -
> -	/*
> -	 * In most cases it's guaranteed that we get here with an RPM
> -	 * reference held, for example because there is a pending GPU
> -	 * request that won't finish until the reset is done. This
> -	 * isn't the case at least when we get here by doing a
> -	 * simulated reset via debugfs, so get an RPM reference.
> -	 */
> -	intel_runtime_pm_get(dev_priv);
> -
> -	engine_mask &= INTEL_INFO(dev_priv)->ring_mask;
> -
> -	if (flags & I915_ERROR_CAPTURE) {
> -		i915_capture_error_state(dev_priv, engine_mask, msg);
> -		i915_clear_error_registers(dev_priv);
> -	}
> -
> -	/*
> -	 * Try engine reset when available. We fall back to full reset if
> -	 * single reset fails.
> -	 */
> -	if (intel_has_reset_engine(dev_priv)) {
> -		for_each_engine_masked(engine, dev_priv, engine_mask, tmp) {
> -			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> -			if (test_and_set_bit(I915_RESET_ENGINE + engine->id,
> -					     &dev_priv->gpu_error.flags))
> -				continue;
> -
> -			if (i915_reset_engine(engine, msg) == 0)
> -				engine_mask &= ~intel_engine_flag(engine);
> -
> -			clear_bit(I915_RESET_ENGINE + engine->id,
> -				  &dev_priv->gpu_error.flags);
> -			wake_up_bit(&dev_priv->gpu_error.flags,
> -				    I915_RESET_ENGINE + engine->id);
> -		}
> -	}
> -
> -	if (!engine_mask)
> -		goto out;
> -
> -	/* Full reset needs the mutex, stop any other user trying to do so. */
> -	if (test_and_set_bit(I915_RESET_BACKOFF, &dev_priv->gpu_error.flags)) {
> -		wait_event(dev_priv->gpu_error.reset_queue,
> -			   !test_bit(I915_RESET_BACKOFF,
> -				     &dev_priv->gpu_error.flags));
> -		goto out;
> -	}
> -
> -	/* Prevent any other reset-engine attempt. */
> -	for_each_engine(engine, dev_priv, tmp) {
> -		while (test_and_set_bit(I915_RESET_ENGINE + engine->id,
> -					&dev_priv->gpu_error.flags))
> -			wait_on_bit(&dev_priv->gpu_error.flags,
> -				    I915_RESET_ENGINE + engine->id,
> -				    TASK_UNINTERRUPTIBLE);
> -	}
> -
> -	i915_reset_device(dev_priv, engine_mask, msg);
> -
> -	for_each_engine(engine, dev_priv, tmp) {
> -		clear_bit(I915_RESET_ENGINE + engine->id,
> -			  &dev_priv->gpu_error.flags);
> -	}
> -
> -	clear_bit(I915_RESET_BACKOFF, &dev_priv->gpu_error.flags);
> -	wake_up_all(&dev_priv->gpu_error.reset_queue);
> -
> -out:
> -	intel_runtime_pm_put(dev_priv);
> -}
> -
>  /* Called from drm generic code, passed 'crtc' which
>   * we use as a pipe index
>   */
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 5c2c93cbab12..9bbea7baa55d 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -29,6 +29,7 @@
>  #include <linux/sched/signal.h>
>  
>  #include "i915_drv.h"
> +#include "i915_reset.h"
>  
>  static const char *i915_fence_get_driver_name(struct dma_fence *fence)
>  {
> diff --git a/drivers/gpu/drm/i915/i915_reset.c b/drivers/gpu/drm/i915/i915_reset.c
> new file mode 100644
> index 000000000000..edf29da15a99
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/i915_reset.c
> @@ -0,0 +1,1271 @@
> +/*
> + * SPDX-License-Identifier: MIT
> + *
> + * Copyright © 2008-2018 Intel Corporation
> + */
> +
> +#include "i915_drv.h"
> +#include "i915_gpu_error.h"
> +#include "i915_reset.h"
> +
> +#include "intel_guc.h"
> +
> +static void engine_skip_context(struct i915_request *rq)
> +{
> +	struct intel_engine_cs *engine = rq->engine;
> +	struct i915_gem_context *hung_ctx = rq->gem_context;
> +	struct i915_timeline *timeline = rq->timeline;
> +	unsigned long flags;
> +
> +	GEM_BUG_ON(timeline == &engine->timeline);
> +
> +	spin_lock_irqsave(&engine->timeline.lock, flags);
> +	spin_lock(&timeline->lock);
> +
> +	list_for_each_entry_continue(rq, &engine->timeline.requests, link)
> +		if (rq->gem_context == hung_ctx)
> +			i915_request_skip(rq, -EIO);
> +
> +	list_for_each_entry(rq, &timeline->requests, link)
> +		i915_request_skip(rq, -EIO);
> +
> +	spin_unlock(&timeline->lock);
> +	spin_unlock_irqrestore(&engine->timeline.lock, flags);
> +}
> +
> +static void client_mark_guilty(struct drm_i915_file_private *file_priv,
> +			       const struct i915_gem_context *ctx)
> +{
> +	unsigned int score;
> +	unsigned long prev_hang;
> +
> +	if (i915_gem_context_is_banned(ctx))
> +		score = I915_CLIENT_SCORE_CONTEXT_BAN;
> +	else
> +		score = 0;
> +
> +	prev_hang = xchg(&file_priv->hang_timestamp, jiffies);
> +	if (time_before(jiffies, prev_hang + I915_CLIENT_FAST_HANG_JIFFIES))
> +		score += I915_CLIENT_SCORE_HANG_FAST;
> +
> +	if (score) {
> +		atomic_add(score, &file_priv->ban_score);
> +
> +		DRM_DEBUG_DRIVER("client %s: gained %u ban score, now %u\n",
> +				 ctx->name, score,
> +				 atomic_read(&file_priv->ban_score));
> +	}
> +}
> +
> +static void context_mark_guilty(struct i915_gem_context *ctx)
> +{
> +	unsigned int score;
> +	bool banned, bannable;
> +
> +	atomic_inc(&ctx->guilty_count);
> +
> +	bannable = i915_gem_context_is_bannable(ctx);
> +	score = atomic_add_return(CONTEXT_SCORE_GUILTY, &ctx->ban_score);
> +	banned = score >= CONTEXT_SCORE_BAN_THRESHOLD;
> +
> +	/* Cool contexts don't accumulate client ban score */
> +	if (!bannable)
> +		return;
> +
> +	if (banned) {
> +		DRM_DEBUG_DRIVER("context %s: guilty %d, score %u, banned\n",
> +				 ctx->name, atomic_read(&ctx->guilty_count),
> +				 score);
> +		i915_gem_context_set_banned(ctx);
> +	}
> +
> +	if (!IS_ERR_OR_NULL(ctx->file_priv))
> +		client_mark_guilty(ctx->file_priv, ctx);
> +}
> +
> +static void context_mark_innocent(struct i915_gem_context *ctx)
> +{
> +	atomic_inc(&ctx->active_count);
> +}
> +
> +static void gen3_stop_engine(struct intel_engine_cs *engine)
> +{
> +	struct drm_i915_private *dev_priv = engine->i915;
> +	const u32 base = engine->mmio_base;
> +
> +	if (intel_engine_stop_cs(engine))
> +		DRM_DEBUG_DRIVER("%s: timed out on STOP_RING\n", engine->name);
> +
> +	I915_WRITE_FW(RING_HEAD(base), I915_READ_FW(RING_TAIL(base)));
> +	POSTING_READ_FW(RING_HEAD(base)); /* paranoia */
> +
> +	I915_WRITE_FW(RING_HEAD(base), 0);
> +	I915_WRITE_FW(RING_TAIL(base), 0);
> +	POSTING_READ_FW(RING_TAIL(base));
> +
> +	/* The ring must be empty before it is disabled */
> +	I915_WRITE_FW(RING_CTL(base), 0);
> +
> +	/* Check acts as a post */
> +	if (I915_READ_FW(RING_HEAD(base)) != 0)
> +		DRM_DEBUG_DRIVER("%s: ring head not parked\n",
> +				 engine->name);
> +}
> +
> +static void i915_stop_engines(struct drm_i915_private *i915,
> +			      unsigned int engine_mask)
> +{
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +
> +	if (INTEL_GEN(i915) < 3)
> +		return;
> +
> +	for_each_engine_masked(engine, i915, engine_mask, id)
> +		gen3_stop_engine(engine);
> +}
> +
> +static bool i915_in_reset(struct pci_dev *pdev)
> +{
> +	u8 gdrst;
> +
> +	pci_read_config_byte(pdev, I915_GDRST, &gdrst);
> +	return gdrst & GRDOM_RESET_STATUS;
> +}
> +
> +static int i915_do_reset(struct drm_i915_private *i915,
> +			 unsigned int engine_mask)
> +{
> +	struct pci_dev *pdev = i915->drm.pdev;
> +	int err;
> +
> +	/* Assert reset for at least 20 usec, and wait for acknowledgement. */
> +	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
> +	usleep_range(50, 200);
> +	err = wait_for(i915_in_reset(pdev), 500);
> +
> +	/* Clear the reset request. */
> +	pci_write_config_byte(pdev, I915_GDRST, 0);
> +	usleep_range(50, 200);
> +	if (!err)
> +		err = wait_for(!i915_in_reset(pdev), 500);
> +
> +	return err;
> +}
> +
> +static bool g4x_reset_complete(struct pci_dev *pdev)
> +{
> +	u8 gdrst;
> +
> +	pci_read_config_byte(pdev, I915_GDRST, &gdrst);
> +	return (gdrst & GRDOM_RESET_ENABLE) == 0;
> +}
> +
> +static int g33_do_reset(struct drm_i915_private *i915, unsigned int engine_mask)
> +{
> +	struct pci_dev *pdev = i915->drm.pdev;
> +
> +	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
> +	return wait_for(g4x_reset_complete(pdev), 500);
> +}
> +
> +static int g4x_do_reset(struct drm_i915_private *dev_priv,
> +			unsigned int engine_mask)
> +{
> +	struct pci_dev *pdev = dev_priv->drm.pdev;
> +	int ret;
> +
> +	/* WaVcpClkGateDisableForMediaReset:ctg,elk */
> +	I915_WRITE(VDECCLK_GATE_D,
> +		   I915_READ(VDECCLK_GATE_D) | VCP_UNIT_CLOCK_GATE_DISABLE);
> +	POSTING_READ(VDECCLK_GATE_D);
> +
> +	pci_write_config_byte(pdev, I915_GDRST,
> +			      GRDOM_MEDIA | GRDOM_RESET_ENABLE);
> +	ret =  wait_for(g4x_reset_complete(pdev), 500);
> +	if (ret) {
> +		DRM_DEBUG_DRIVER("Wait for media reset failed\n");
> +		goto out;
> +	}
> +
> +	pci_write_config_byte(pdev, I915_GDRST,
> +			      GRDOM_RENDER | GRDOM_RESET_ENABLE);
> +	ret =  wait_for(g4x_reset_complete(pdev), 500);
> +	if (ret) {
> +		DRM_DEBUG_DRIVER("Wait for render reset failed\n");
> +		goto out;
> +	}
> +
> +out:
> +	pci_write_config_byte(pdev, I915_GDRST, 0);
> +
> +	I915_WRITE(VDECCLK_GATE_D,
> +		   I915_READ(VDECCLK_GATE_D) & ~VCP_UNIT_CLOCK_GATE_DISABLE);
> +	POSTING_READ(VDECCLK_GATE_D);
> +
> +	return ret;
> +}
> +
> +static int ironlake_do_reset(struct drm_i915_private *dev_priv,
> +			     unsigned int engine_mask)
> +{
> +	int ret;
> +
> +	I915_WRITE(ILK_GDSR, ILK_GRDOM_RENDER | ILK_GRDOM_RESET_ENABLE);
> +	ret = intel_wait_for_register(dev_priv,
> +				      ILK_GDSR, ILK_GRDOM_RESET_ENABLE, 0,
> +				      500);
> +	if (ret) {
> +		DRM_DEBUG_DRIVER("Wait for render reset failed\n");
> +		goto out;
> +	}
> +
> +	I915_WRITE(ILK_GDSR, ILK_GRDOM_MEDIA | ILK_GRDOM_RESET_ENABLE);
> +	ret = intel_wait_for_register(dev_priv,
> +				      ILK_GDSR, ILK_GRDOM_RESET_ENABLE, 0,
> +				      500);
> +	if (ret) {
> +		DRM_DEBUG_DRIVER("Wait for media reset failed\n");
> +		goto out;
> +	}
> +
> +out:
> +	I915_WRITE(ILK_GDSR, 0);
> +	POSTING_READ(ILK_GDSR);
> +	return ret;
> +}
> +
> +/* Reset the hardware domains (GENX_GRDOM_*) specified by mask */
> +static int gen6_hw_domain_reset(struct drm_i915_private *dev_priv,
> +				u32 hw_domain_mask)
> +{
> +	int err;
> +
> +	/*
> +	 * GEN6_GDRST is not in the gt power well, no need to check
> +	 * for fifo space for the write or forcewake the chip for
> +	 * the read
> +	 */
> +	I915_WRITE_FW(GEN6_GDRST, hw_domain_mask);
> +
> +	/* Wait for the device to ack the reset requests */
> +	err = __intel_wait_for_register_fw(dev_priv,
> +					   GEN6_GDRST, hw_domain_mask, 0,
> +					   500, 0,
> +					   NULL);
> +	if (err)
> +		DRM_DEBUG_DRIVER("Wait for 0x%08x engines reset failed\n",
> +				 hw_domain_mask);
> +
> +	return err;
> +}
> +
> +static int gen6_reset_engines(struct drm_i915_private *i915,
> +			      unsigned int engine_mask)
> +{
> +	struct intel_engine_cs *engine;
> +	const u32 hw_engine_mask[I915_NUM_ENGINES] = {
> +		[RCS] = GEN6_GRDOM_RENDER,
> +		[BCS] = GEN6_GRDOM_BLT,
> +		[VCS] = GEN6_GRDOM_MEDIA,
> +		[VCS2] = GEN8_GRDOM_MEDIA2,
> +		[VECS] = GEN6_GRDOM_VECS,
> +	};
> +	u32 hw_mask;
> +
> +	if (engine_mask == ALL_ENGINES) {
> +		hw_mask = GEN6_GRDOM_FULL;
> +	} else {
> +		unsigned int tmp;
> +
> +		hw_mask = 0;
> +		for_each_engine_masked(engine, i915, engine_mask, tmp)
> +			hw_mask |= hw_engine_mask[engine->id];
> +	}
> +
> +	return gen6_hw_domain_reset(i915, hw_mask);
> +}
> +
> +static int gen11_reset_engines(struct drm_i915_private *i915,
> +			       unsigned int engine_mask)
> +{
> +	struct intel_engine_cs *engine;
> +	const u32 hw_engine_mask[I915_NUM_ENGINES] = {
> +		[RCS] = GEN11_GRDOM_RENDER,
> +		[BCS] = GEN11_GRDOM_BLT,
> +		[VCS] = GEN11_GRDOM_MEDIA,
> +		[VCS2] = GEN11_GRDOM_MEDIA2,
> +		[VCS3] = GEN11_GRDOM_MEDIA3,
> +		[VCS4] = GEN11_GRDOM_MEDIA4,
> +		[VECS] = GEN11_GRDOM_VECS,
> +		[VECS2] = GEN11_GRDOM_VECS2,
> +	};
> +	u32 hw_mask;
> +
> +	BUILD_BUG_ON(VECS2 + 1 != I915_NUM_ENGINES);
> +
> +	if (engine_mask == ALL_ENGINES) {
> +		hw_mask = GEN11_GRDOM_FULL;
> +	} else {
> +		unsigned int tmp;
> +
> +		hw_mask = 0;
> +		for_each_engine_masked(engine, i915, engine_mask, tmp)
> +			hw_mask |= hw_engine_mask[engine->id];
> +	}
> +
> +	return gen6_hw_domain_reset(i915, hw_mask);
> +}
> +
> +static int gen8_reset_engine_start(struct intel_engine_cs *engine)
> +{
> +	struct drm_i915_private *dev_priv = engine->i915;
> +	int ret;
> +
> +	I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
> +		      _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
> +
> +	ret = __intel_wait_for_register_fw(dev_priv,
> +					   RING_RESET_CTL(engine->mmio_base),
> +					   RESET_CTL_READY_TO_RESET,
> +					   RESET_CTL_READY_TO_RESET,
> +					   700, 0,
> +					   NULL);
> +	if (ret)
> +		DRM_ERROR("%s: reset request timeout\n", engine->name);
> +
> +	return ret;
> +}
> +
> +static void gen8_reset_engine_cancel(struct intel_engine_cs *engine)
> +{
> +	struct drm_i915_private *dev_priv = engine->i915;
> +
> +	I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
> +		      _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET));
> +}
> +
> +static int gen8_reset_engines(struct drm_i915_private *i915,
> +			      unsigned int engine_mask)
> +{
> +	struct intel_engine_cs *engine;
> +	unsigned int tmp;
> +	int ret;
> +
> +	for_each_engine_masked(engine, i915, engine_mask, tmp) {
> +		if (gen8_reset_engine_start(engine)) {
> +			ret = -EIO;
> +			goto not_ready;
> +		}
> +	}
> +
> +	if (INTEL_GEN(i915) >= 11)
> +		ret = gen11_reset_engines(i915, engine_mask);
> +	else
> +		ret = gen6_reset_engines(i915, engine_mask);
> +
> +not_ready:
> +	for_each_engine_masked(engine, i915, engine_mask, tmp)
> +		gen8_reset_engine_cancel(engine);
> +
> +	return ret;
> +}
> +
> +typedef int (*reset_func)(struct drm_i915_private *, unsigned int engine_mask);
> +
> +static reset_func intel_get_gpu_reset(struct drm_i915_private *i915)
> +{
> +	if (!i915_modparams.reset)
> +		return NULL;
> +
> +	if (INTEL_GEN(i915) >= 8)
> +		return gen8_reset_engines;
> +	else if (INTEL_GEN(i915) >= 6)
> +		return gen6_reset_engines;
> +	else if (IS_GEN5(i915))
> +		return ironlake_do_reset;
> +	else if (IS_G4X(i915))
> +		return g4x_do_reset;
> +	else if (IS_G33(i915) || IS_PINEVIEW(i915))
> +		return g33_do_reset;
> +	else if (INTEL_GEN(i915) >= 3)
> +		return i915_do_reset;
> +	else
> +		return NULL;
> +}
> +
> +int intel_gpu_reset(struct drm_i915_private *i915, unsigned int engine_mask)
> +{
> +	reset_func reset = intel_get_gpu_reset(i915);
> +	int retry;
> +	int ret;
> +
> +	/*
> +	 * We want to perform per-engine reset from atomic context (e.g.
> +	 * softirq), which imposes the constraint that we cannot sleep.
> +	 * However, experience suggests that spending a bit of time waiting
> +	 * for a reset helps in various cases, so for a full-device reset
> +	 * we apply the opposite rule and wait if we want to. As we should
> +	 * always follow up a failed per-engine reset with a full device reset,
> +	 * being a little faster, stricter and more error prone for the
> +	 * atomic case seems an acceptable compromise.
> +	 *
> +	 * Unfortunately this leads to a bimodal routine, when the goal was
> +	 * to have a single reset function that worked for resetting any
> +	 * number of engines simultaneously.
> +	 */
> +	might_sleep_if(engine_mask == ALL_ENGINES);
> +
> +	/*
> +	 * If the power well sleeps during the reset, the reset
> +	 * request may be dropped and never completes (causing -EIO).
> +	 */
> +	intel_uncore_forcewake_get(i915, FORCEWAKE_ALL);
> +	for (retry = 0; retry < 3; retry++) {
> +		/*
> +		 * We stop engines, otherwise we might get failed reset and a
> +		 * dead gpu (on elk). Also as modern gpu as kbl can suffer
> +		 * from system hang if batchbuffer is progressing when
> +		 * the reset is issued, regardless of READY_TO_RESET ack.
> +		 * Thus assume it is best to stop engines on all gens
> +		 * where we have a gpu reset.
> +		 *
> +		 * WaKBLVECSSemaphoreWaitPoll:kbl (on ALL_ENGINES)
> +		 *
> +		 * WaMediaResetMainRingCleanup:ctg,elk (presumably)
> +		 *
> +		 * FIXME: Wa for more modern gens needs to be validated
> +		 */
> +		i915_stop_engines(i915, engine_mask);
> +
> +		ret = -ENODEV;
> +		if (reset) {
> +			GEM_TRACE("engine_mask=%x\n", engine_mask);
> +			ret = reset(i915, engine_mask);
> +		}
> +		if (ret != -ETIMEDOUT || engine_mask != ALL_ENGINES)
> +			break;
> +
> +		cond_resched();
> +	}
> +	intel_uncore_forcewake_put(i915, FORCEWAKE_ALL);
> +
> +	return ret;
> +}
> +
> +bool intel_has_gpu_reset(struct drm_i915_private *i915)
> +{
> +	return intel_get_gpu_reset(i915);
> +}
> +
> +bool intel_has_reset_engine(struct drm_i915_private *i915)
> +{
> +	return i915->info.has_reset_engine && i915_modparams.reset >= 2;
> +}
> +
> +int intel_reset_guc(struct drm_i915_private *i915)
> +{
> +	u32 guc_domain =
> +		INTEL_GEN(i915) >= 11 ? GEN11_GRDOM_GUC : GEN9_GRDOM_GUC;
> +	int ret;
> +
> +	GEM_BUG_ON(!HAS_GUC(i915));
> +
> +	intel_uncore_forcewake_get(i915, FORCEWAKE_ALL);
> +	ret = gen6_hw_domain_reset(i915, guc_domain);
> +	intel_uncore_forcewake_put(i915, FORCEWAKE_ALL);
> +
> +	return ret;
> +}
> +
> +/*
> + * Ensure irq handler finishes, and not run again.
> + * Also return the active request so that we only search for it once.
> + */
> +static struct i915_request *
> +reset_prepare_engine(struct intel_engine_cs *engine)
> +{
> +	struct i915_request *rq;
> +
> +	/*
> +	 * During the reset sequence, we must prevent the engine from
> +	 * entering RC6. As the context state is undefined until we restart
> +	 * the engine, if it does enter RC6 during the reset, the state
> +	 * written to the powercontext is undefined and so we may lose
> +	 * GPU state upon resume, i.e. fail to restart after a reset.
> +	 */
> +	intel_uncore_forcewake_get(engine->i915, FORCEWAKE_ALL);
> +
> +	rq = engine->reset.prepare(engine);
> +	if (rq && rq->fence.error == -EIO)
> +		rq = ERR_PTR(-EIO); /* Previous reset failed! */
> +
> +	return rq;
> +}
> +
> +static int reset_prepare(struct drm_i915_private *i915)
> +{
> +	struct intel_engine_cs *engine;
> +	struct i915_request *rq;
> +	enum intel_engine_id id;
> +	int err = 0;
> +
> +	disable_irq(i915->drm.irq);
> +
> +	for_each_engine(engine, i915, id) {
> +		rq = reset_prepare_engine(engine);
> +		if (IS_ERR(rq)) {
> +			err = PTR_ERR(rq);
> +			continue;
> +		}
> +
> +		engine->hangcheck.active_request = rq;
> +	}
> +
> +	i915_gem_revoke_fences(i915);
> +	intel_uc_sanitize(i915);
> +
> +	return err;
> +}
> +
> +/* Returns the request if it was guilty of the hang */
> +static struct i915_request *
> +reset_request(struct intel_engine_cs *engine,
> +	      struct i915_request *rq,
> +	      bool stalled)
> +{
> +	/*
> +	 * The guilty request will get skipped on a hung engine.
> +	 *
> +	 * Users of client default contexts do not rely on logical
> +	 * state preserved between batches so it is safe to execute
> +	 * queued requests following the hang. Non default contexts
> +	 * rely on preserved state, so skipping a batch loses the
> +	 * evolution of the state and it needs to be considered corrupted.
> +	 * Executing more queued batches on top of corrupted state is
> +	 * risky. But we take the risk by trying to advance through
> +	 * the queued requests in order to make the client behaviour
> +	 * more predictable around resets, by not throwing away random
> +	 * amount of batches it has prepared for execution. Sophisticated
> +	 * clients can use gem_reset_stats_ioctl and dma fence status
> +	 * (exported via sync_file info ioctl on explicit fences) to observe
> +	 * when it loses the context state and should rebuild accordingly.
> +	 *
> +	 * The context ban, and ultimately the client ban, mechanism are safety
> +	 * valves if client submission ends up resulting in nothing more than
> +	 * subsequent hangs.
> +	 */
> +
> +	if (i915_request_completed(rq)) {
> +		GEM_TRACE("%s pardoned global=%d (fence %llx:%d), current %d\n",
> +			  engine->name, rq->global_seqno,
> +			  rq->fence.context, rq->fence.seqno,
> +			  intel_engine_get_seqno(engine));
> +		stalled = false;
> +	}
> +
> +	if (stalled) {
> +		context_mark_guilty(rq->gem_context);
> +		i915_request_skip(rq, -EIO);
> +
> +		/* If this context is now banned, skip all pending requests. */
> +		if (i915_gem_context_is_banned(rq->gem_context))
> +			engine_skip_context(rq);
> +	} else {
> +		/*
> +		 * Since this is not the hung engine, it may have advanced
> +		 * since the hang declaration. Double check by refinding
> +		 * the active request at the time of the reset.
> +		 */
> +		rq = i915_gem_find_active_request(engine);
> +		if (rq) {
> +			unsigned long flags;
> +
> +			context_mark_innocent(rq->gem_context);
> +			dma_fence_set_error(&rq->fence, -EAGAIN);
> +
> +			/* Rewind the engine to replay the incomplete rq */
> +			spin_lock_irqsave(&engine->timeline.lock, flags);
> +			rq = list_prev_entry(rq, link);
> +			if (&rq->link == &engine->timeline.requests)
> +				rq = NULL;
> +			spin_unlock_irqrestore(&engine->timeline.lock, flags);
> +		}
> +	}
> +
> +	return rq;
> +}
> +
> +static void reset_engine(struct intel_engine_cs *engine,
> +			 struct i915_request *rq,
> +			 bool stalled)
> +{
> +	/*
> +	 * Make sure this write is visible before we re-enable the interrupt
> +	 * handlers on another CPU, as tasklet_enable() resolves to just
> +	 * a compiler barrier which is insufficient for our purpose here.
> +	 */
> +	smp_store_mb(engine->irq_posted, 0);
> +
> +	if (rq)
> +		rq = reset_request(engine, rq, stalled);
> +
> +	/* Setup the CS to resume from the breadcrumb of the hung request */
> +	engine->reset.reset(engine, rq);
> +}
> +
> +static void gt_reset(struct drm_i915_private *i915, unsigned int stalled_mask)
> +{
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +
> +	lockdep_assert_held(&i915->drm.struct_mutex);
> +
> +	i915_retire_requests(i915);
> +
> +	for_each_engine(engine, i915, id) {
> +		struct intel_context *ce;
> +
> +		reset_engine(engine,
> +			     engine->hangcheck.active_request,
> +			     stalled_mask & ENGINE_MASK(id));
> +		ce = fetch_and_zero(&engine->last_retired_context);
> +		if (ce)
> +			intel_context_unpin(ce);
> +
> +		/*
> +		 * Ostensibily, we always want a context loaded for powersaving,
> +		 * so if the engine is idle after the reset, send a request
> +		 * to load our scratch kernel_context.
> +		 *
> +		 * More mysteriously, if we leave the engine idle after a reset,
> +		 * the next userspace batch may hang, with what appears to be
> +		 * an incoherent read by the CS (presumably stale TLB). An
> +		 * empty request appears sufficient to paper over the glitch.
> +		 */
> +		if (intel_engine_is_idle(engine)) {
> +			struct i915_request *rq;
> +
> +			rq = i915_request_alloc(engine, i915->kernel_context);
> +			if (!IS_ERR(rq))
> +				i915_request_add(rq);
> +		}
> +	}
> +
> +	i915_gem_restore_fences(i915);
> +}
> +
> +static void reset_finish_engine(struct intel_engine_cs *engine)
> +{
> +	engine->reset.finish(engine);
> +
> +	intel_uncore_forcewake_put(engine->i915, FORCEWAKE_ALL);
> +}
> +
> +static void reset_finish(struct drm_i915_private *i915)
> +{
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +
> +	lockdep_assert_held(&i915->drm.struct_mutex);
> +
> +	for_each_engine(engine, i915, id) {
> +		engine->hangcheck.active_request = NULL;
> +		reset_finish_engine(engine);
> +	}
> +
> +	enable_irq(i915->drm.irq);
> +}
> +
> +static void nop_submit_request(struct i915_request *rq)
> +{
> +	GEM_TRACE("%s fence %llx:%d -> -EIO\n",
> +		  rq->engine->name, rq->fence.context, rq->fence.seqno);
> +	dma_fence_set_error(&rq->fence, -EIO);
> +
> +	i915_request_submit(rq);
> +}
> +
> +static void nop_complete_submit_request(struct i915_request *rq)
> +{
> +	unsigned long flags;
> +
> +	GEM_TRACE("%s fence %llx:%d -> -EIO\n",
> +		  rq->engine->name,
> +		  rq->fence.context, rq->fence.seqno);
> +	dma_fence_set_error(&rq->fence, -EIO);
> +
> +	spin_lock_irqsave(&rq->engine->timeline.lock, flags);
> +	__i915_request_submit(rq);
> +	intel_engine_init_global_seqno(rq->engine, rq->global_seqno);
> +	spin_unlock_irqrestore(&rq->engine->timeline.lock, flags);
> +}
> +
> +void i915_gem_set_wedged(struct drm_i915_private *i915)
> +{
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +
> +	GEM_TRACE("start\n");
> +
> +	if (GEM_SHOW_DEBUG()) {
> +		struct drm_printer p = drm_debug_printer(__func__);
> +
> +		for_each_engine(engine, i915, id)
> +			intel_engine_dump(engine, &p, "%s\n", engine->name);
> +	}
> +
> +	set_bit(I915_WEDGED, &i915->gpu_error.flags);
> +	smp_mb__after_atomic();
> +
> +	/*
> +	 * First, stop submission to hw, but do not yet complete requests by
> +	 * rolling the global seqno forward (since this would complete requests
> +	 * for which we haven't set the fence error to EIO yet).
> +	 */
> +	for_each_engine(engine, i915, id) {
> +		reset_prepare_engine(engine);
> +
> +		engine->submit_request = nop_submit_request;
> +		engine->schedule = NULL;
> +	}
> +	i915->caps.scheduler = 0;
> +
> +	/* Even if the GPU reset fails, it should still stop the engines */
> +	intel_gpu_reset(i915, ALL_ENGINES);
> +
> +	/*
> +	 * Make sure no one is running the old callback before we proceed with
> +	 * cancelling requests and resetting the completion tracking. Otherwise
> +	 * we might submit a request to the hardware which never completes.
> +	 */
> +	synchronize_rcu();
> +
> +	for_each_engine(engine, i915, id) {
> +		/* Mark all executing requests as skipped */
> +		engine->cancel_requests(engine);
> +
> +		/*
> +		 * Only once we've force-cancelled all in-flight requests can we
> +		 * start to complete all requests.
> +		 */
> +		engine->submit_request = nop_complete_submit_request;
> +	}
> +
> +	/*
> +	 * Make sure no request can slip through without getting completed by
> +	 * either this call here to intel_engine_init_global_seqno, or the one
> +	 * in nop_complete_submit_request.
> +	 */
> +	synchronize_rcu();
> +
> +	for_each_engine(engine, i915, id) {
> +		unsigned long flags;
> +
> +		/*
> +		 * Mark all pending requests as complete so that any concurrent
> +		 * (lockless) lookup doesn't try and wait upon the request as we
> +		 * reset it.
> +		 */
> +		spin_lock_irqsave(&engine->timeline.lock, flags);
> +		intel_engine_init_global_seqno(engine,
> +					       intel_engine_last_submit(engine));
> +		spin_unlock_irqrestore(&engine->timeline.lock, flags);
> +
> +		reset_finish_engine(engine);
> +	}
> +
> +	GEM_TRACE("end\n");
> +
> +	wake_up_all(&i915->gpu_error.reset_queue);
> +}
> +
> +bool i915_gem_unset_wedged(struct drm_i915_private *i915)
> +{
> +	struct i915_timeline *tl;
> +
> +	lockdep_assert_held(&i915->drm.struct_mutex);
> +	if (!test_bit(I915_WEDGED, &i915->gpu_error.flags))
> +		return true;
> +
> +	GEM_TRACE("start\n");
> +
> +	/*
> +	 * Before unwedging, make sure that all pending operations
> +	 * are flushed and errored out - we may have requests waiting upon
> +	 * third party fences. We marked all inflight requests as EIO, and
> +	 * every execbuf since returned EIO, for consistency we want all
> +	 * the currently pending requests to also be marked as EIO, which
> +	 * is done inside our nop_submit_request - and so we must wait.
> +	 *
> +	 * No more can be submitted until we reset the wedged bit.
> +	 */
> +	list_for_each_entry(tl, &i915->gt.timelines, link) {
> +		struct i915_request *rq;
> +
> +		rq = i915_gem_active_peek(&tl->last_request,
> +					  &i915->drm.struct_mutex);
> +		if (!rq)
> +			continue;
> +
> +		/*
> +		 * We can't use our normal waiter as we want to
> +		 * avoid recursively trying to handle the current
> +		 * reset. The basic dma_fence_default_wait() installs
> +		 * a callback for dma_fence_signal(), which is
> +		 * triggered by our nop handler (indirectly, the
> +		 * callback enables the signaler thread which is
> +		 * woken by the nop_submit_request() advancing the seqno
> +		 * and when the seqno passes the fence, the signaler
> +		 * then signals the fence waking us up).
> +		 */
> +		if (dma_fence_default_wait(&rq->fence, true,
> +					   MAX_SCHEDULE_TIMEOUT) < 0)
> +			return false;
> +	}
> +	i915_retire_requests(i915);
> +	GEM_BUG_ON(i915->gt.active_requests);
> +
> +	/*
> +	 * Undo nop_submit_request. We prevent all new i915 requests from
> +	 * being queued (by disallowing execbuf whilst wedged) so having
> +	 * waited for all active requests above, we know the system is idle
> +	 * and do not have to worry about a thread being inside
> +	 * engine->submit_request() as we swap over. So unlike installing
> +	 * the nop_submit_request on reset, we can do this from normal
> +	 * context and do not require stop_machine().
> +	 */
> +	intel_engines_reset_default_submission(i915);
> +	i915_gem_contexts_lost(i915);
> +
> +	GEM_TRACE("end\n");
> +
> +	smp_mb__before_atomic(); /* complete takeover before enabling execbuf */
> +	clear_bit(I915_WEDGED, &i915->gpu_error.flags);
> +
> +	return true;
> +}
> +
> +/**
> + * i915_reset - reset chip after a hang
> + * @i915: #drm_i915_private to reset
> + * @stalled_mask: mask of the stalled engines with the guilty requests
> + * @reason: user error message for why we are resetting
> + *
> + * Reset the chip.  Useful if a hang is detected. Marks the device as wedged
> + * on failure.
> + *
> + * Caller must hold the struct_mutex.
> + *
> + * Procedure is fairly simple:
> + *   - reset the chip using the reset reg
> + *   - re-init context state
> + *   - re-init hardware status page
> + *   - re-init ring buffer
> + *   - re-init interrupt state
> + *   - re-init display
> + */
> +void i915_reset(struct drm_i915_private *i915,
> +		unsigned int stalled_mask,
> +		const char *reason)
> +{
> +	struct i915_gpu_error *error = &i915->gpu_error;
> +	int ret;
> +	int i;
> +
> +	GEM_TRACE("flags=%lx\n", error->flags);
> +
> +	might_sleep();
> +	lockdep_assert_held(&i915->drm.struct_mutex);
> +	GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, &error->flags));
> +
> +	if (!test_bit(I915_RESET_HANDOFF, &error->flags))
> +		return;
> +
> +	/* Clear any previous failed attempts at recovery. Time to try again. */
> +	if (!i915_gem_unset_wedged(i915))
> +		goto wakeup;
> +
> +	if (reason)
> +		dev_notice(i915->drm.dev, "Resetting chip for %s\n", reason);
> +	error->reset_count++;
> +
> +	ret = reset_prepare(i915);
> +	if (ret) {
> +		dev_err(i915->drm.dev, "GPU recovery failed\n");
> +		goto taint;
> +	}
> +
> +	if (!intel_has_gpu_reset(i915)) {
> +		if (i915_modparams.reset)
> +			dev_err(i915->drm.dev, "GPU reset not supported\n");
> +		else
> +			DRM_DEBUG_DRIVER("GPU reset disabled\n");
> +		goto error;
> +	}
> +
> +	for (i = 0; i < 3; i++) {
> +		ret = intel_gpu_reset(i915, ALL_ENGINES);
> +		if (ret == 0)
> +			break;
> +
> +		msleep(100);
> +	}
> +	if (ret) {
> +		dev_err(i915->drm.dev, "Failed to reset chip\n");
> +		goto taint;
> +	}
> +
> +	/* Ok, now get things going again... */
> +
> +	/*
> +	 * Everything depends on having the GTT running, so we need to start
> +	 * there.
> +	 */
> +	ret = i915_ggtt_enable_hw(i915);
> +	if (ret) {
> +		DRM_ERROR("Failed to re-enable GGTT following reset (%d)\n",
> +			  ret);
> +		goto error;
> +	}
> +
> +	gt_reset(i915, stalled_mask);
> +	intel_overlay_reset(i915);
> +
> +	/*
> +	 * Next we need to restore the context, but we don't use those
> +	 * yet either...
> +	 *
> +	 * Ring buffer needs to be re-initialized in the KMS case, or if X
> +	 * was running at the time of the reset (i.e. we weren't VT
> +	 * switched away).
> +	 */
> +	ret = i915_gem_init_hw(i915);
> +	if (ret) {
> +		DRM_ERROR("Failed to initialise HW following reset (%d)\n",
> +			  ret);
> +		goto error;
> +	}
> +
> +	i915_queue_hangcheck(i915);
> +
> +finish:
> +	reset_finish(i915);
> +wakeup:
> +	clear_bit(I915_RESET_HANDOFF, &error->flags);
> +	wake_up_bit(&error->flags, I915_RESET_HANDOFF);
> +	return;
> +
> +taint:
> +	/*
> +	 * History tells us that if we cannot reset the GPU now, we
> +	 * never will. This then impacts everything that is run
> +	 * subsequently. On failing the reset, we mark the driver
> +	 * as wedged, preventing further execution on the GPU.
> +	 * We also want to go one step further and add a taint to the
> +	 * kernel so that any subsequent faults can be traced back to
> +	 * this failure. This is important for CI, where if the
> +	 * GPU/driver fails we would like to reboot and restart testing
> +	 * rather than continue on into oblivion. For everyone else,
> +	 * the system should still plod along, but they have been warned!
> +	 */
> +	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
> +error:
> +	i915_gem_set_wedged(i915);
> +	i915_retire_requests(i915);
> +	goto finish;
> +}
> +
> +static inline int intel_gt_reset_engine(struct drm_i915_private *i915,
> +					struct intel_engine_cs *engine)
> +{
> +	return intel_gpu_reset(i915, intel_engine_flag(engine));
> +}
> +
> +/**
> + * i915_reset_engine - reset GPU engine to recover from a hang
> + * @engine: engine to reset
> + * @msg: reason for GPU reset; or NULL for no dev_notice()
> + *
> + * Reset a specific GPU engine. Useful if a hang is detected.
> + * Returns zero on successful reset or otherwise an error code.
> + *
> + * Procedure is:
> + *  - identifies the request that caused the hang and it is dropped
> + *  - reset engine (which will force the engine to idle)
> + *  - re-init/configure engine
> + */
> +int i915_reset_engine(struct intel_engine_cs *engine, const char *msg)
> +{
> +	struct i915_gpu_error *error = &engine->i915->gpu_error;
> +	struct i915_request *active_request;
> +	int ret;
> +
> +	GEM_TRACE("%s flags=%lx\n", engine->name, error->flags);
> +	GEM_BUG_ON(!test_bit(I915_RESET_ENGINE + engine->id, &error->flags));
> +
> +	active_request = reset_prepare_engine(engine);
> +	if (IS_ERR_OR_NULL(active_request)) {
> +		/* Either the previous reset failed, or we pardon the reset. */
> +		ret = PTR_ERR(active_request);
> +		goto out;
> +	}
> +
> +	if (msg)
> +		dev_notice(engine->i915->drm.dev,
> +			   "Resetting %s for %s\n", engine->name, msg);
> +	error->reset_engine_count[engine->id]++;
> +
> +	if (!engine->i915->guc.execbuf_client)
> +		ret = intel_gt_reset_engine(engine->i915, engine);
> +	else
> +		ret = intel_guc_reset_engine(&engine->i915->guc, engine);
> +	if (ret) {
> +		/* If we fail here, we expect to fallback to a global reset */
> +		DRM_DEBUG_DRIVER("%sFailed to reset %s, ret=%d\n",
> +				 engine->i915->guc.execbuf_client ? "GuC " : "",
> +				 engine->name, ret);
> +		goto out;
> +	}
> +
> +	/*
> +	 * The request that caused the hang is stuck on elsp, we know the
> +	 * active request and can drop it, adjust head to skip the offending
> +	 * request to resume executing remaining requests in the queue.
> +	 */
> +	reset_engine(engine, active_request, true);
> +
> +	/*
> +	 * The engine and its registers (and workarounds in case of render)
> +	 * have been reset to their default values. Follow the init_ring
> +	 * process to program RING_MODE, HWSP and re-enable submission.
> +	 */
> +	ret = engine->init_hw(engine);
> +	if (ret)
> +		goto out;
> +
> +out:
> +	reset_finish_engine(engine);
> +	return ret;
> +}
> +
> +struct wedge_me {
> +	struct delayed_work work;
> +	struct drm_i915_private *i915;
> +	const char *name;
> +};
> +
> +static void wedge_me(struct work_struct *work)
> +{
> +	struct wedge_me *w = container_of(work, typeof(*w), work.work);
> +
> +	dev_err(w->i915->drm.dev,
> +		"%s timed out, cancelling all in-flight rendering.\n",
> +		w->name);
> +	i915_gem_set_wedged(w->i915);
> +}
> +
> +static void __init_wedge(struct wedge_me *w,
> +			 struct drm_i915_private *i915,
> +			 long timeout,
> +			 const char *name)
> +{
> +	w->i915 = i915;
> +	w->name = name;
> +
> +	INIT_DELAYED_WORK_ONSTACK(&w->work, wedge_me);
> +	schedule_delayed_work(&w->work, timeout);
> +}
> +
> +static void __fini_wedge(struct wedge_me *w)
> +{
> +	cancel_delayed_work_sync(&w->work);
> +	destroy_delayed_work_on_stack(&w->work);
> +	w->i915 = NULL;
> +}
> +
> +#define i915_wedge_on_timeout(W, DEV, TIMEOUT)				\
> +	for (__init_wedge((W), (DEV), (TIMEOUT), __func__);		\
> +	     (W)->i915;							\
> +	     __fini_wedge((W)))
> +
> +static void i915_reset_device(struct drm_i915_private *i915,
> +			      u32 engine_mask,
> +			      const char *reason)
> +{
> +	struct i915_gpu_error *error = &i915->gpu_error;
> +	struct kobject *kobj = &i915->drm.primary->kdev->kobj;
> +	char *error_event[] = { I915_ERROR_UEVENT "=1", NULL };
> +	char *reset_event[] = { I915_RESET_UEVENT "=1", NULL };
> +	char *reset_done_event[] = { I915_ERROR_UEVENT "=0", NULL };
> +	struct wedge_me w;
> +
> +	kobject_uevent_env(kobj, KOBJ_CHANGE, error_event);
> +
> +	DRM_DEBUG_DRIVER("resetting chip\n");
> +	kobject_uevent_env(kobj, KOBJ_CHANGE, reset_event);
> +
> +	/* Use a watchdog to ensure that our reset completes */
> +	i915_wedge_on_timeout(&w, i915, 5 * HZ) {
> +		intel_prepare_reset(i915);
> +
> +		error->reason = reason;
> +		error->stalled_mask = engine_mask;
> +
> +		/* Signal that locked waiters should reset the GPU */
> +		smp_mb__before_atomic();
> +		set_bit(I915_RESET_HANDOFF, &error->flags);
> +		wake_up_all(&error->wait_queue);
> +
> +		/*
> +		 * Wait for anyone holding the lock to wakeup, without
> +		 * blocking indefinitely on struct_mutex.
> +		 */
> +		do {
> +			if (mutex_trylock(&i915->drm.struct_mutex)) {
> +				i915_reset(i915, engine_mask, reason);
> +				mutex_unlock(&i915->drm.struct_mutex);
> +			}
> +		} while (wait_on_bit_timeout(&error->flags,
> +					     I915_RESET_HANDOFF,
> +					     TASK_UNINTERRUPTIBLE,
> +					     1));
> +
> +		error->stalled_mask = 0;
> +		error->reason = NULL;
> +
> +		intel_finish_reset(i915);
> +	}
> +
> +	if (!test_bit(I915_WEDGED, &error->flags))
> +		kobject_uevent_env(kobj, KOBJ_CHANGE, reset_done_event);
> +}
> +
> +static void i915_clear_error_registers(struct drm_i915_private *dev_priv)
> +{
> +	u32 eir;
> +
> +	if (!IS_GEN2(dev_priv))
> +		I915_WRITE(PGTBL_ER, I915_READ(PGTBL_ER));
> +
> +	if (INTEL_GEN(dev_priv) < 4)
> +		I915_WRITE(IPEIR, I915_READ(IPEIR));
> +	else
> +		I915_WRITE(IPEIR_I965, I915_READ(IPEIR_I965));
> +
> +	I915_WRITE(EIR, I915_READ(EIR));
> +	eir = I915_READ(EIR);
> +	if (eir) {
> +		/*
> +		 * some errors might have become stuck,
> +		 * mask them.
> +		 */
> +		DRM_DEBUG_DRIVER("EIR stuck: 0x%08x, masking\n", eir);
> +		I915_WRITE(EMR, I915_READ(EMR) | eir);
> +		I915_WRITE(IIR, I915_MASTER_ERROR_INTERRUPT);
> +	}
> +}
> +
> +/**
> + * i915_handle_error - handle a gpu error
> + * @i915: i915 device private
> + * @engine_mask: mask representing engines that are hung
> + * @flags: control flags
> + * @fmt: Error message format string
> + *
> + * Do some basic checking of register state at error time and
> + * dump it to the syslog.  Also call i915_capture_error_state() to make
> + * sure we get a record and make it available in debugfs.  Fire a uevent
> + * so userspace knows something bad happened (should trigger collection
> + * of a ring dump etc.).
> + */
> +void i915_handle_error(struct drm_i915_private *i915,
> +		       u32 engine_mask,
> +		       unsigned long flags,
> +		       const char *fmt, ...)
> +{
> +	struct intel_engine_cs *engine;
> +	unsigned int tmp;
> +	char error_msg[80];
> +	char *msg = NULL;
> +
> +	if (fmt) {
> +		va_list args;
> +
> +		va_start(args, fmt);
> +		vscnprintf(error_msg, sizeof(error_msg), fmt, args);
> +		va_end(args);
> +
> +		msg = error_msg;
> +	}
> +
> +	/*
> +	 * In most cases it's guaranteed that we get here with an RPM
> +	 * reference held, for example because there is a pending GPU
> +	 * request that won't finish until the reset is done. This
> +	 * isn't the case at least when we get here by doing a
> +	 * simulated reset via debugfs, so get an RPM reference.
> +	 */
> +	intel_runtime_pm_get(i915);
> +
> +	engine_mask &= INTEL_INFO(i915)->ring_mask;
> +
> +	if (flags & I915_ERROR_CAPTURE) {
> +		i915_capture_error_state(i915, engine_mask, msg);
> +		i915_clear_error_registers(i915);
> +	}
> +
> +	/*
> +	 * Try engine reset when available. We fall back to full reset if
> +	 * single reset fails.
> +	 */
> +	if (intel_has_reset_engine(i915)) {
> +		for_each_engine_masked(engine, i915, engine_mask, tmp) {
> +			BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> +			if (test_and_set_bit(I915_RESET_ENGINE + engine->id,
> +					     &i915->gpu_error.flags))
> +				continue;
> +
> +			if (i915_reset_engine(engine, msg) == 0)
> +				engine_mask &= ~intel_engine_flag(engine);
> +
> +			clear_bit(I915_RESET_ENGINE + engine->id,
> +				  &i915->gpu_error.flags);
> +			wake_up_bit(&i915->gpu_error.flags,
> +				    I915_RESET_ENGINE + engine->id);
> +		}
> +	}
> +
> +	if (!engine_mask)
> +		goto out;
> +
> +	/* Full reset needs the mutex, stop any other user trying to do so. */
> +	if (test_and_set_bit(I915_RESET_BACKOFF, &i915->gpu_error.flags)) {
> +		wait_event(i915->gpu_error.reset_queue,
> +			   !test_bit(I915_RESET_BACKOFF,
> +				     &i915->gpu_error.flags));
> +		goto out;
> +	}
> +
> +	/* Prevent any other reset-engine attempt. */
> +	for_each_engine(engine, i915, tmp) {
> +		while (test_and_set_bit(I915_RESET_ENGINE + engine->id,
> +					&i915->gpu_error.flags))
> +			wait_on_bit(&i915->gpu_error.flags,
> +				    I915_RESET_ENGINE + engine->id,
> +				    TASK_UNINTERRUPTIBLE);
> +	}
> +
> +	i915_reset_device(i915, engine_mask, msg);
> +
> +	for_each_engine(engine, i915, tmp) {
> +		clear_bit(I915_RESET_ENGINE + engine->id,
> +			  &i915->gpu_error.flags);
> +	}
> +
> +	clear_bit(I915_RESET_BACKOFF, &i915->gpu_error.flags);
> +	wake_up_all(&i915->gpu_error.reset_queue);
> +
> +out:
> +	intel_runtime_pm_put(i915);
> +}
> diff --git a/drivers/gpu/drm/i915/i915_reset.h b/drivers/gpu/drm/i915/i915_reset.h
> new file mode 100644
> index 000000000000..09422c4772dd
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/i915_reset.h
> @@ -0,0 +1,37 @@
> +/*
> + * SPDX-License-Identifier: MIT
> + *
> + * Copyright © 2008-2018 Intel Corporation
> + */
> +
> +#ifndef I915_RESET_H
> +#define I915_RESET_H
> +
> +#include <linux/compiler.h>
> +#include <linux/types.h>
> +
> +struct drm_i915_private;
> +struct intel_engine_cs;
> +struct intel_guc;
> +
> +__printf(4, 5)
> +void i915_handle_error(struct drm_i915_private *i915,
> +		       u32 engine_mask,
> +		       unsigned long flags,
> +		       const char *fmt, ...);
> +#define I915_ERROR_CAPTURE BIT(0)
> +
> +void i915_reset(struct drm_i915_private *i915,
> +		unsigned int stalled_mask,
> +		const char *reason);
> +int i915_reset_engine(struct intel_engine_cs *engine,
> +		      const char *reason);
> +
> +bool intel_has_gpu_reset(struct drm_i915_private *i915);
> +bool intel_has_reset_engine(struct drm_i915_private *i915);
> +
> +int intel_gpu_reset(struct drm_i915_private *i915, u32 engine_mask);
> +
> +int intel_reset_guc(struct drm_i915_private *i915);
> +
> +#endif /* I915_RESET_H */
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 7998e70a3174..8a07de5ac740 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -33,13 +33,7 @@
>  #include <linux/vgaarb.h>
>  #include <drm/drm_edid.h>
>  #include <drm/drmP.h>
> -#include "intel_drv.h"
> -#include "intel_frontbuffer.h"
>  #include <drm/i915_drm.h>
> -#include "i915_drv.h"
> -#include "i915_gem_clflush.h"
> -#include "intel_dsi.h"
> -#include "i915_trace.h"
>  #include <drm/drm_atomic.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_dp_helper.h>
> @@ -49,6 +43,15 @@
>  #include <linux/dma_remapping.h>
>  #include <linux/reservation.h>
>  
> +#include "intel_drv.h"
> +#include "intel_dsi.h"
> +#include "intel_frontbuffer.h"
> +
> +#include "i915_drv.h"
> +#include "i915_gem_clflush.h"
> +#include "i915_reset.h"
> +#include "i915_trace.h"
> +
>  /* Primary plane formats for gen <= 3 */
>  static const uint32_t i8xx_primary_formats[] = {
>  	DRM_FORMAT_C8,
> diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
> index 4121928a495e..df1a384c2f92 100644
> --- a/drivers/gpu/drm/i915/intel_guc.h
> +++ b/drivers/gpu/drm/i915/intel_guc.h
> @@ -189,4 +189,7 @@ static inline void intel_guc_disable_msg(struct intel_guc *guc, u32 mask)
>  	spin_unlock_irq(&guc->irq_lock);
>  }
>  
> +int intel_guc_reset_engine(struct intel_guc *guc,
> +			   struct intel_engine_cs *engine);
> +
>  #endif
> diff --git a/drivers/gpu/drm/i915/intel_hangcheck.c b/drivers/gpu/drm/i915/intel_hangcheck.c
> index 2fc7a0dd0df9..5141df342884 100644
> --- a/drivers/gpu/drm/i915/intel_hangcheck.c
> +++ b/drivers/gpu/drm/i915/intel_hangcheck.c
> @@ -23,6 +23,7 @@
>   */
>  
>  #include "i915_drv.h"
> +#include "i915_reset.h"
>  
>  static bool
>  ipehr_is_semaphore_wait(struct intel_engine_cs *engine, u32 ipehr)
> diff --git a/drivers/gpu/drm/i915/intel_uc.c b/drivers/gpu/drm/i915/intel_uc.c
> index 7c95697e1a35..88352ff7164a 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -26,6 +26,7 @@
>  #include "intel_guc_submission.h"
>  #include "intel_guc.h"
>  #include "i915_drv.h"
> +#include "i915_reset.h"
>  
>  static void guc_free_load_err_log(struct intel_guc *guc);
>  
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index b892ca8396e8..1abd342e9cce 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -1698,258 +1698,6 @@ int i915_reg_read_ioctl(struct drm_device *dev,
>  	return ret;
>  }
>  
> -static void gen3_stop_engine(struct intel_engine_cs *engine)
> -{
> -	struct drm_i915_private *dev_priv = engine->i915;
> -	const u32 base = engine->mmio_base;
> -
> -	if (intel_engine_stop_cs(engine))
> -		DRM_DEBUG_DRIVER("%s: timed out on STOP_RING\n", engine->name);
> -
> -	I915_WRITE_FW(RING_HEAD(base), I915_READ_FW(RING_TAIL(base)));
> -	POSTING_READ_FW(RING_HEAD(base)); /* paranoia */
> -
> -	I915_WRITE_FW(RING_HEAD(base), 0);
> -	I915_WRITE_FW(RING_TAIL(base), 0);
> -	POSTING_READ_FW(RING_TAIL(base));
> -
> -	/* The ring must be empty before it is disabled */
> -	I915_WRITE_FW(RING_CTL(base), 0);
> -
> -	/* Check acts as a post */
> -	if (I915_READ_FW(RING_HEAD(base)) != 0)
> -		DRM_DEBUG_DRIVER("%s: ring head not parked\n",
> -				 engine->name);
> -}
> -
> -static void i915_stop_engines(struct drm_i915_private *dev_priv,
> -			      unsigned engine_mask)
> -{
> -	struct intel_engine_cs *engine;
> -	enum intel_engine_id id;
> -
> -	if (INTEL_GEN(dev_priv) < 3)
> -		return;
> -
> -	for_each_engine_masked(engine, dev_priv, engine_mask, id)
> -		gen3_stop_engine(engine);
> -}
> -
> -static bool i915_in_reset(struct pci_dev *pdev)
> -{
> -	u8 gdrst;
> -
> -	pci_read_config_byte(pdev, I915_GDRST, &gdrst);
> -	return gdrst & GRDOM_RESET_STATUS;
> -}
> -
> -static int i915_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> -{
> -	struct pci_dev *pdev = dev_priv->drm.pdev;
> -	int err;
> -
> -	/* Assert reset for at least 20 usec, and wait for acknowledgement. */
> -	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
> -	usleep_range(50, 200);
> -	err = wait_for(i915_in_reset(pdev), 500);
> -
> -	/* Clear the reset request. */
> -	pci_write_config_byte(pdev, I915_GDRST, 0);
> -	usleep_range(50, 200);
> -	if (!err)
> -		err = wait_for(!i915_in_reset(pdev), 500);
> -
> -	return err;
> -}
> -
> -static bool g4x_reset_complete(struct pci_dev *pdev)
> -{
> -	u8 gdrst;
> -
> -	pci_read_config_byte(pdev, I915_GDRST, &gdrst);
> -	return (gdrst & GRDOM_RESET_ENABLE) == 0;
> -}
> -
> -static int g33_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> -{
> -	struct pci_dev *pdev = dev_priv->drm.pdev;
> -
> -	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
> -	return wait_for(g4x_reset_complete(pdev), 500);
> -}
> -
> -static int g4x_do_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> -{
> -	struct pci_dev *pdev = dev_priv->drm.pdev;
> -	int ret;
> -
> -	/* WaVcpClkGateDisableForMediaReset:ctg,elk */
> -	I915_WRITE(VDECCLK_GATE_D,
> -		   I915_READ(VDECCLK_GATE_D) | VCP_UNIT_CLOCK_GATE_DISABLE);
> -	POSTING_READ(VDECCLK_GATE_D);
> -
> -	pci_write_config_byte(pdev, I915_GDRST,
> -			      GRDOM_MEDIA | GRDOM_RESET_ENABLE);
> -	ret =  wait_for(g4x_reset_complete(pdev), 500);
> -	if (ret) {
> -		DRM_DEBUG_DRIVER("Wait for media reset failed\n");
> -		goto out;
> -	}
> -
> -	pci_write_config_byte(pdev, I915_GDRST,
> -			      GRDOM_RENDER | GRDOM_RESET_ENABLE);
> -	ret =  wait_for(g4x_reset_complete(pdev), 500);
> -	if (ret) {
> -		DRM_DEBUG_DRIVER("Wait for render reset failed\n");
> -		goto out;
> -	}
> -
> -out:
> -	pci_write_config_byte(pdev, I915_GDRST, 0);
> -
> -	I915_WRITE(VDECCLK_GATE_D,
> -		   I915_READ(VDECCLK_GATE_D) & ~VCP_UNIT_CLOCK_GATE_DISABLE);
> -	POSTING_READ(VDECCLK_GATE_D);
> -
> -	return ret;
> -}
> -
> -static int ironlake_do_reset(struct drm_i915_private *dev_priv,
> -			     unsigned engine_mask)
> -{
> -	int ret;
> -
> -	I915_WRITE(ILK_GDSR, ILK_GRDOM_RENDER | ILK_GRDOM_RESET_ENABLE);
> -	ret = intel_wait_for_register(dev_priv,
> -				      ILK_GDSR, ILK_GRDOM_RESET_ENABLE, 0,
> -				      500);
> -	if (ret) {
> -		DRM_DEBUG_DRIVER("Wait for render reset failed\n");
> -		goto out;
> -	}
> -
> -	I915_WRITE(ILK_GDSR, ILK_GRDOM_MEDIA | ILK_GRDOM_RESET_ENABLE);
> -	ret = intel_wait_for_register(dev_priv,
> -				      ILK_GDSR, ILK_GRDOM_RESET_ENABLE, 0,
> -				      500);
> -	if (ret) {
> -		DRM_DEBUG_DRIVER("Wait for media reset failed\n");
> -		goto out;
> -	}
> -
> -out:
> -	I915_WRITE(ILK_GDSR, 0);
> -	POSTING_READ(ILK_GDSR);
> -	return ret;
> -}
> -
> -/* Reset the hardware domains (GENX_GRDOM_*) specified by mask */
> -static int gen6_hw_domain_reset(struct drm_i915_private *dev_priv,
> -				u32 hw_domain_mask)
> -{
> -	int err;
> -
> -	/* GEN6_GDRST is not in the gt power well, no need to check
> -	 * for fifo space for the write or forcewake the chip for
> -	 * the read
> -	 */
> -	__raw_i915_write32(dev_priv, GEN6_GDRST, hw_domain_mask);
> -
> -	/* Wait for the device to ack the reset requests */
> -	err = __intel_wait_for_register_fw(dev_priv,
> -					   GEN6_GDRST, hw_domain_mask, 0,
> -					   500, 0,
> -					   NULL);
> -	if (err)
> -		DRM_DEBUG_DRIVER("Wait for 0x%08x engines reset failed\n",
> -				 hw_domain_mask);
> -
> -	return err;
> -}
> -
> -/**
> - * gen6_reset_engines - reset individual engines
> - * @dev_priv: i915 device
> - * @engine_mask: mask of intel_ring_flag() engines or ALL_ENGINES for full reset
> - *
> - * This function will reset the individual engines that are set in engine_mask.
> - * If you provide ALL_ENGINES as mask, full global domain reset will be issued.
> - *
> - * Note: It is responsibility of the caller to handle the difference between
> - * asking full domain reset versus reset for all available individual engines.
> - *
> - * Returns 0 on success, nonzero on error.
> - */
> -static int gen6_reset_engines(struct drm_i915_private *dev_priv,
> -			      unsigned engine_mask)
> -{
> -	struct intel_engine_cs *engine;
> -	const u32 hw_engine_mask[I915_NUM_ENGINES] = {
> -		[RCS] = GEN6_GRDOM_RENDER,
> -		[BCS] = GEN6_GRDOM_BLT,
> -		[VCS] = GEN6_GRDOM_MEDIA,
> -		[VCS2] = GEN8_GRDOM_MEDIA2,
> -		[VECS] = GEN6_GRDOM_VECS,
> -	};
> -	u32 hw_mask;
> -
> -	if (engine_mask == ALL_ENGINES) {
> -		hw_mask = GEN6_GRDOM_FULL;
> -	} else {
> -		unsigned int tmp;
> -
> -		hw_mask = 0;
> -		for_each_engine_masked(engine, dev_priv, engine_mask, tmp)
> -			hw_mask |= hw_engine_mask[engine->id];
> -	}
> -
> -	return gen6_hw_domain_reset(dev_priv, hw_mask);
> -}
> -
> -/**
> - * gen11_reset_engines - reset individual engines
> - * @dev_priv: i915 device
> - * @engine_mask: mask of intel_ring_flag() engines or ALL_ENGINES for full reset
> - *
> - * This function will reset the individual engines that are set in engine_mask.
> - * If you provide ALL_ENGINES as mask, full global domain reset will be issued.
> - *
> - * Note: It is responsibility of the caller to handle the difference between
> - * asking full domain reset versus reset for all available individual engines.
> - *
> - * Returns 0 on success, nonzero on error.
> - */
> -static int gen11_reset_engines(struct drm_i915_private *dev_priv,
> -			       unsigned engine_mask)
> -{
> -	struct intel_engine_cs *engine;
> -	const u32 hw_engine_mask[I915_NUM_ENGINES] = {
> -		[RCS] = GEN11_GRDOM_RENDER,
> -		[BCS] = GEN11_GRDOM_BLT,
> -		[VCS] = GEN11_GRDOM_MEDIA,
> -		[VCS2] = GEN11_GRDOM_MEDIA2,
> -		[VCS3] = GEN11_GRDOM_MEDIA3,
> -		[VCS4] = GEN11_GRDOM_MEDIA4,
> -		[VECS] = GEN11_GRDOM_VECS,
> -		[VECS2] = GEN11_GRDOM_VECS2,
> -	};
> -	u32 hw_mask;
> -
> -	BUILD_BUG_ON(VECS2 + 1 != I915_NUM_ENGINES);
> -
> -	if (engine_mask == ALL_ENGINES) {
> -		hw_mask = GEN11_GRDOM_FULL;
> -	} else {
> -		unsigned int tmp;
> -
> -		hw_mask = 0;
> -		for_each_engine_masked(engine, dev_priv, engine_mask, tmp)
> -			hw_mask |= hw_engine_mask[engine->id];
> -	}
> -
> -	return gen6_hw_domain_reset(dev_priv, hw_mask);
> -}
> -
>  /**
>   * __intel_wait_for_register_fw - wait until register matches expected state
>   * @dev_priv: the i915 device
> @@ -2060,169 +1808,6 @@ int __intel_wait_for_register(struct drm_i915_private *dev_priv,
>  	return ret;
>  }
>  
> -static int gen8_reset_engine_start(struct intel_engine_cs *engine)
> -{
> -	struct drm_i915_private *dev_priv = engine->i915;
> -	int ret;
> -
> -	I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
> -		      _MASKED_BIT_ENABLE(RESET_CTL_REQUEST_RESET));
> -
> -	ret = __intel_wait_for_register_fw(dev_priv,
> -					   RING_RESET_CTL(engine->mmio_base),
> -					   RESET_CTL_READY_TO_RESET,
> -					   RESET_CTL_READY_TO_RESET,
> -					   700, 0,
> -					   NULL);
> -	if (ret)
> -		DRM_ERROR("%s: reset request timeout\n", engine->name);
> -
> -	return ret;
> -}
> -
> -static void gen8_reset_engine_cancel(struct intel_engine_cs *engine)
> -{
> -	struct drm_i915_private *dev_priv = engine->i915;
> -
> -	I915_WRITE_FW(RING_RESET_CTL(engine->mmio_base),
> -		      _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET));
> -}
> -
> -static int gen8_reset_engines(struct drm_i915_private *dev_priv,
> -			      unsigned engine_mask)
> -{
> -	struct intel_engine_cs *engine;
> -	unsigned int tmp;
> -	int ret;
> -
> -	for_each_engine_masked(engine, dev_priv, engine_mask, tmp) {
> -		if (gen8_reset_engine_start(engine)) {
> -			ret = -EIO;
> -			goto not_ready;
> -		}
> -	}
> -
> -	if (INTEL_GEN(dev_priv) >= 11)
> -		ret = gen11_reset_engines(dev_priv, engine_mask);
> -	else
> -		ret = gen6_reset_engines(dev_priv, engine_mask);
> -
> -not_ready:
> -	for_each_engine_masked(engine, dev_priv, engine_mask, tmp)
> -		gen8_reset_engine_cancel(engine);
> -
> -	return ret;
> -}
> -
> -typedef int (*reset_func)(struct drm_i915_private *, unsigned engine_mask);
> -
> -static reset_func intel_get_gpu_reset(struct drm_i915_private *dev_priv)
> -{
> -	if (!i915_modparams.reset)
> -		return NULL;
> -
> -	if (INTEL_GEN(dev_priv) >= 8)
> -		return gen8_reset_engines;
> -	else if (INTEL_GEN(dev_priv) >= 6)
> -		return gen6_reset_engines;
> -	else if (IS_GEN5(dev_priv))
> -		return ironlake_do_reset;
> -	else if (IS_G4X(dev_priv))
> -		return g4x_do_reset;
> -	else if (IS_G33(dev_priv) || IS_PINEVIEW(dev_priv))
> -		return g33_do_reset;
> -	else if (INTEL_GEN(dev_priv) >= 3)
> -		return i915_do_reset;
> -	else
> -		return NULL;
> -}
> -
> -int intel_gpu_reset(struct drm_i915_private *dev_priv, unsigned engine_mask)
> -{
> -	reset_func reset = intel_get_gpu_reset(dev_priv);
> -	int retry;
> -	int ret;
> -
> -	/*
> -	 * We want to perform per-engine reset from atomic context (e.g.
> -	 * softirq), which imposes the constraint that we cannot sleep.
> -	 * However, experience suggests that spending a bit of time waiting
> -	 * for a reset helps in various cases, so for a full-device reset
> -	 * we apply the opposite rule and wait if we want to. As we should
> -	 * always follow up a failed per-engine reset with a full device reset,
> -	 * being a little faster, stricter and more error prone for the
> -	 * atomic case seems an acceptable compromise.
> -	 *
> -	 * Unfortunately this leads to a bimodal routine, when the goal was
> -	 * to have a single reset function that worked for resetting any
> -	 * number of engines simultaneously.
> -	 */
> -	might_sleep_if(engine_mask == ALL_ENGINES);
> -
> -	/*
> -	 * If the power well sleeps during the reset, the reset
> -	 * request may be dropped and never completes (causing -EIO).
> -	 */
> -	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
> -	for (retry = 0; retry < 3; retry++) {
> -
> -		/*
> -		 * We stop engines, otherwise we might get failed reset and a
> -		 * dead gpu (on elk). Also as modern gpu as kbl can suffer
> -		 * from system hang if batchbuffer is progressing when
> -		 * the reset is issued, regardless of READY_TO_RESET ack.
> -		 * Thus assume it is best to stop engines on all gens
> -		 * where we have a gpu reset.
> -		 *
> -		 * WaKBLVECSSemaphoreWaitPoll:kbl (on ALL_ENGINES)
> -		 *
> -		 * WaMediaResetMainRingCleanup:ctg,elk (presumably)
> -		 *
> -		 * FIXME: Wa for more modern gens needs to be validated
> -		 */
> -		i915_stop_engines(dev_priv, engine_mask);
> -
> -		ret = -ENODEV;
> -		if (reset) {
> -			GEM_TRACE("engine_mask=%x\n", engine_mask);
> -			ret = reset(dev_priv, engine_mask);
> -		}
> -		if (ret != -ETIMEDOUT || engine_mask != ALL_ENGINES)
> -			break;
> -
> -		cond_resched();
> -	}
> -	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
> -
> -	return ret;
> -}
> -
> -bool intel_has_gpu_reset(struct drm_i915_private *dev_priv)
> -{
> -	return intel_get_gpu_reset(dev_priv) != NULL;
> -}
> -
> -bool intel_has_reset_engine(struct drm_i915_private *dev_priv)
> -{
> -	return (dev_priv->info.has_reset_engine &&
> -		i915_modparams.reset >= 2);
> -}
> -
> -int intel_reset_guc(struct drm_i915_private *dev_priv)
> -{
> -	u32 guc_domain = INTEL_GEN(dev_priv) >= 11 ? GEN11_GRDOM_GUC :
> -						     GEN9_GRDOM_GUC;
> -	int ret;
> -
> -	GEM_BUG_ON(!HAS_GUC(dev_priv));
> -
> -	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
> -	ret = gen6_hw_domain_reset(dev_priv, guc_domain);
> -	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
> -
> -	return ret;
> -}
> -
>  bool intel_uncore_unclaimed_mmio(struct drm_i915_private *dev_priv)
>  {
>  	return check_for_unclaimed_mmio(dev_priv);
> diff --git a/drivers/gpu/drm/i915/selftests/intel_workarounds.c b/drivers/gpu/drm/i915/selftests/intel_workarounds.c
> index fafdec3fe83e..7f842dbbea1f 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_workarounds.c
> @@ -5,6 +5,7 @@
>   */
>  
>  #include "../i915_selftest.h"
> +#include "../i915_reset.h"
>  
>  #include "mock_context.h"
>  
> -- 
> 2.18.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch


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