drm/i915: Move GraphicsTechnology files under gt/

Start partitioning off the code that talks to the hardware (GT) from the
uapi layers and move the device facing code under gt/

One casualty is s/intel_ringbuffer.h/intel_engine.h/ with the plan to
subdivide that header and body further (and split out the submission
code from the ringbuffer and logical context handling). This patch aims
to be simple motion so git can fixup inflight patches with little mess.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190424174839.7141-1-chris@chris-wilson.co.uk

1 files changed, 1471 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
new file mode 100644
index 000000000000..7db498567843
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -0,0 +1,1471 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2008-2018 Intel Corporation
+ */
+
+#include <linux/sched/mm.h>
+#include <linux/stop_machine.h>
+
+#include "i915_drv.h"
+#include "i915_gpu_error.h"
+#include "intel_reset.h"
+
+#include "intel_guc.h"
+
+#define RESET_MAX_RETRIES 3
+
+/* XXX How to handle concurrent GGTT updates using tiling registers? */
+#define RESET_UNDER_STOP_MACHINE 0
+
+static void rmw_set(struct intel_uncore *uncore, i915_reg_t reg, u32 set)
+{
+	intel_uncore_rmw(uncore, reg, 0, set);
+}
+
+static void rmw_clear(struct intel_uncore *uncore, i915_reg_t reg, u32 clr)
+{
+	intel_uncore_rmw(uncore, reg, clr, 0);
+}
+
+static void rmw_set_fw(struct intel_uncore *uncore, i915_reg_t reg, u32 set)
+{
+	intel_uncore_rmw_fw(uncore, reg, 0, set);
+}
+
+static void rmw_clear_fw(struct intel_uncore *uncore, i915_reg_t reg, u32 clr)
+{
+	intel_uncore_rmw_fw(uncore, reg, clr, 0);
+}
+
+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;
+
+	lockdep_assert_held(&engine->timeline.lock);
+
+	if (!i915_request_is_active(rq))
+		return;
+
+	list_for_each_entry_continue(rq, &engine->timeline.requests, link)
+		if (rq->gem_context == hung_ctx)
+			i915_request_skip(rq, -EIO);
+}
+
+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 bool context_mark_guilty(struct i915_gem_context *ctx)
+{
+	unsigned long prev_hang;
+	bool banned;
+	int i;
+
+	atomic_inc(&ctx->guilty_count);
+
+	/* Cool contexts are too cool to be banned! (Used for reset testing.) */
+	if (!i915_gem_context_is_bannable(ctx))
+		return false;
+
+	/* Record the timestamp for the last N hangs */
+	prev_hang = ctx->hang_timestamp[0];
+	for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp) - 1; i++)
+		ctx->hang_timestamp[i] = ctx->hang_timestamp[i + 1];
+	ctx->hang_timestamp[i] = jiffies;
+
+	/* If we have hung N+1 times in rapid succession, we ban the context! */
+	banned = !i915_gem_context_is_recoverable(ctx);
+	if (time_before(jiffies, prev_hang + CONTEXT_FAST_HANG_JIFFIES))
+		banned = true;
+	if (banned) {
+		DRM_DEBUG_DRIVER("context %s: guilty %d, banned\n",
+				 ctx->name, atomic_read(&ctx->guilty_count));
+		i915_gem_context_set_banned(ctx);
+	}
+
+	if (!IS_ERR_OR_NULL(ctx->file_priv))
+		client_mark_guilty(ctx->file_priv, ctx);
+
+	return banned;
+}
+
+static void context_mark_innocent(struct i915_gem_context *ctx)
+{
+	atomic_inc(&ctx->active_count);
+}
+
+void i915_reset_request(struct i915_request *rq, bool guilty)
+{
+	GEM_TRACE("%s rq=%llx:%lld, guilty? %s\n",
+		  rq->engine->name,
+		  rq->fence.context,
+		  rq->fence.seqno,
+		  yesno(guilty));
+
+	lockdep_assert_held(&rq->engine->timeline.lock);
+	GEM_BUG_ON(i915_request_completed(rq));
+
+	if (guilty) {
+		i915_request_skip(rq, -EIO);
+		if (context_mark_guilty(rq->gem_context))
+			engine_skip_context(rq);
+	} else {
+		dma_fence_set_error(&rq->fence, -EAGAIN);
+		context_mark_innocent(rq->gem_context);
+	}
+}
+
+static void gen3_stop_engine(struct intel_engine_cs *engine)
+{
+	struct intel_uncore *uncore = engine->uncore;
+	const u32 base = engine->mmio_base;
+
+	GEM_TRACE("%s\n", engine->name);
+
+	if (intel_engine_stop_cs(engine))
+		GEM_TRACE("%s: timed out on STOP_RING\n", engine->name);
+
+	intel_uncore_write_fw(uncore,
+			      RING_HEAD(base),
+			      intel_uncore_read_fw(uncore, RING_TAIL(base)));
+	intel_uncore_posting_read_fw(uncore, RING_HEAD(base)); /* paranoia */
+
+	intel_uncore_write_fw(uncore, RING_HEAD(base), 0);
+	intel_uncore_write_fw(uncore, RING_TAIL(base), 0);
+	intel_uncore_posting_read_fw(uncore, RING_TAIL(base));
+
+	/* The ring must be empty before it is disabled */
+	intel_uncore_write_fw(uncore, RING_CTL(base), 0);
+
+	/* Check acts as a post */
+	if (intel_uncore_read_fw(uncore, RING_HEAD(base)))
+		GEM_TRACE("%s: ring head [%x] not parked\n",
+			  engine->name,
+			  intel_uncore_read_fw(uncore, RING_HEAD(base)));
+}
+
+static void i915_stop_engines(struct drm_i915_private *i915,
+			      intel_engine_mask_t engine_mask)
+{
+	struct intel_engine_cs *engine;
+	intel_engine_mask_t tmp;
+
+	if (INTEL_GEN(i915) < 3)
+		return;
+
+	for_each_engine_masked(engine, i915, engine_mask, tmp)
+		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,
+			 intel_engine_mask_t engine_mask,
+			 unsigned int retry)
+{
+	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);
+	udelay(50);
+	err = wait_for_atomic(i915_in_reset(pdev), 50);
+
+	/* Clear the reset request. */
+	pci_write_config_byte(pdev, I915_GDRST, 0);
+	udelay(50);
+	if (!err)
+		err = wait_for_atomic(!i915_in_reset(pdev), 50);
+
+	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,
+			intel_engine_mask_t engine_mask,
+			unsigned int retry)
+{
+	struct pci_dev *pdev = i915->drm.pdev;
+
+	pci_write_config_byte(pdev, I915_GDRST, GRDOM_RESET_ENABLE);
+	return wait_for_atomic(g4x_reset_complete(pdev), 50);
+}
+
+static int g4x_do_reset(struct drm_i915_private *i915,
+			intel_engine_mask_t engine_mask,
+			unsigned int retry)
+{
+	struct pci_dev *pdev = i915->drm.pdev;
+	struct intel_uncore *uncore = &i915->uncore;
+	int ret;
+
+	/* WaVcpClkGateDisableForMediaReset:ctg,elk */
+	rmw_set_fw(uncore, VDECCLK_GATE_D, VCP_UNIT_CLOCK_GATE_DISABLE);
+	intel_uncore_posting_read_fw(uncore, VDECCLK_GATE_D);
+
+	pci_write_config_byte(pdev, I915_GDRST,
+			      GRDOM_MEDIA | GRDOM_RESET_ENABLE);
+	ret =  wait_for_atomic(g4x_reset_complete(pdev), 50);
+	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_atomic(g4x_reset_complete(pdev), 50);
+	if (ret) {
+		DRM_DEBUG_DRIVER("Wait for render reset failed\n");
+		goto out;
+	}
+
+out:
+	pci_write_config_byte(pdev, I915_GDRST, 0);
+
+	rmw_clear_fw(uncore, VDECCLK_GATE_D, VCP_UNIT_CLOCK_GATE_DISABLE);
+	intel_uncore_posting_read_fw(uncore, VDECCLK_GATE_D);
+
+	return ret;
+}
+
+static int ironlake_do_reset(struct drm_i915_private *i915,
+			     intel_engine_mask_t engine_mask,
+			     unsigned int retry)
+{
+	struct intel_uncore *uncore = &i915->uncore;
+	int ret;
+
+	intel_uncore_write_fw(uncore, ILK_GDSR,
+			      ILK_GRDOM_RENDER | ILK_GRDOM_RESET_ENABLE);
+	ret = __intel_wait_for_register_fw(uncore, ILK_GDSR,
+					   ILK_GRDOM_RESET_ENABLE, 0,
+					   5000, 0,
+					   NULL);
+	if (ret) {
+		DRM_DEBUG_DRIVER("Wait for render reset failed\n");
+		goto out;
+	}
+
+	intel_uncore_write_fw(uncore, ILK_GDSR,
+			      ILK_GRDOM_MEDIA | ILK_GRDOM_RESET_ENABLE);
+	ret = __intel_wait_for_register_fw(uncore, ILK_GDSR,
+					   ILK_GRDOM_RESET_ENABLE, 0,
+					   5000, 0,
+					   NULL);
+	if (ret) {
+		DRM_DEBUG_DRIVER("Wait for media reset failed\n");
+		goto out;
+	}
+
+out:
+	intel_uncore_write_fw(uncore, ILK_GDSR, 0);
+	intel_uncore_posting_read_fw(uncore, ILK_GDSR);
+	return ret;
+}
+
+/* Reset the hardware domains (GENX_GRDOM_*) specified by mask */
+static int gen6_hw_domain_reset(struct drm_i915_private *i915,
+				u32 hw_domain_mask)
+{
+	struct intel_uncore *uncore = &i915->uncore;
+	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
+	 */
+	intel_uncore_write_fw(uncore, GEN6_GDRST, hw_domain_mask);
+
+	/* Wait for the device to ack the reset requests */
+	err = __intel_wait_for_register_fw(uncore,
+					   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,
+			      intel_engine_mask_t engine_mask,
+			      unsigned int retry)
+{
+	struct intel_engine_cs *engine;
+	const u32 hw_engine_mask[] = {
+		[RCS0]  = GEN6_GRDOM_RENDER,
+		[BCS0]  = GEN6_GRDOM_BLT,
+		[VCS0]  = GEN6_GRDOM_MEDIA,
+		[VCS1]  = GEN8_GRDOM_MEDIA2,
+		[VECS0] = GEN6_GRDOM_VECS,
+	};
+	u32 hw_mask;
+
+	if (engine_mask == ALL_ENGINES) {
+		hw_mask = GEN6_GRDOM_FULL;
+	} else {
+		intel_engine_mask_t tmp;
+
+		hw_mask = 0;
+		for_each_engine_masked(engine, i915, engine_mask, tmp) {
+			GEM_BUG_ON(engine->id >= ARRAY_SIZE(hw_engine_mask));
+			hw_mask |= hw_engine_mask[engine->id];
+		}
+	}
+
+	return gen6_hw_domain_reset(i915, hw_mask);
+}
+
+static u32 gen11_lock_sfc(struct intel_engine_cs *engine)
+{
+	struct intel_uncore *uncore = engine->uncore;
+	u8 vdbox_sfc_access = RUNTIME_INFO(engine->i915)->vdbox_sfc_access;
+	i915_reg_t sfc_forced_lock, sfc_forced_lock_ack;
+	u32 sfc_forced_lock_bit, sfc_forced_lock_ack_bit;
+	i915_reg_t sfc_usage;
+	u32 sfc_usage_bit;
+	u32 sfc_reset_bit;
+
+	switch (engine->class) {
+	case VIDEO_DECODE_CLASS:
+		if ((BIT(engine->instance) & vdbox_sfc_access) == 0)
+			return 0;
+
+		sfc_forced_lock = GEN11_VCS_SFC_FORCED_LOCK(engine);
+		sfc_forced_lock_bit = GEN11_VCS_SFC_FORCED_LOCK_BIT;
+
+		sfc_forced_lock_ack = GEN11_VCS_SFC_LOCK_STATUS(engine);
+		sfc_forced_lock_ack_bit  = GEN11_VCS_SFC_LOCK_ACK_BIT;
+
+		sfc_usage = GEN11_VCS_SFC_LOCK_STATUS(engine);
+		sfc_usage_bit = GEN11_VCS_SFC_USAGE_BIT;
+		sfc_reset_bit = GEN11_VCS_SFC_RESET_BIT(engine->instance);
+		break;
+
+	case VIDEO_ENHANCEMENT_CLASS:
+		sfc_forced_lock = GEN11_VECS_SFC_FORCED_LOCK(engine);
+		sfc_forced_lock_bit = GEN11_VECS_SFC_FORCED_LOCK_BIT;
+
+		sfc_forced_lock_ack = GEN11_VECS_SFC_LOCK_ACK(engine);
+		sfc_forced_lock_ack_bit  = GEN11_VECS_SFC_LOCK_ACK_BIT;
+
+		sfc_usage = GEN11_VECS_SFC_USAGE(engine);
+		sfc_usage_bit = GEN11_VECS_SFC_USAGE_BIT;
+		sfc_reset_bit = GEN11_VECS_SFC_RESET_BIT(engine->instance);
+		break;
+
+	default:
+		return 0;
+	}
+
+	/*
+	 * Tell the engine that a software reset is going to happen. The engine
+	 * will then try to force lock the SFC (if currently locked, it will
+	 * remain so until we tell the engine it is safe to unlock; if currently
+	 * unlocked, it will ignore this and all new lock requests). If SFC
+	 * ends up being locked to the engine we want to reset, we have to reset
+	 * it as well (we will unlock it once the reset sequence is completed).
+	 */
+	rmw_set_fw(uncore, sfc_forced_lock, sfc_forced_lock_bit);
+
+	if (__intel_wait_for_register_fw(uncore,
+					 sfc_forced_lock_ack,
+					 sfc_forced_lock_ack_bit,
+					 sfc_forced_lock_ack_bit,
+					 1000, 0, NULL)) {
+		DRM_DEBUG_DRIVER("Wait for SFC forced lock ack failed\n");
+		return 0;
+	}
+
+	if (intel_uncore_read_fw(uncore, sfc_usage) & sfc_usage_bit)
+		return sfc_reset_bit;
+
+	return 0;
+}
+
+static void gen11_unlock_sfc(struct intel_engine_cs *engine)
+{
+	struct intel_uncore *uncore = engine->uncore;
+	u8 vdbox_sfc_access = RUNTIME_INFO(engine->i915)->vdbox_sfc_access;
+	i915_reg_t sfc_forced_lock;
+	u32 sfc_forced_lock_bit;
+
+	switch (engine->class) {
+	case VIDEO_DECODE_CLASS:
+		if ((BIT(engine->instance) & vdbox_sfc_access) == 0)
+			return;
+
+		sfc_forced_lock = GEN11_VCS_SFC_FORCED_LOCK(engine);
+		sfc_forced_lock_bit = GEN11_VCS_SFC_FORCED_LOCK_BIT;
+		break;
+
+	case VIDEO_ENHANCEMENT_CLASS:
+		sfc_forced_lock = GEN11_VECS_SFC_FORCED_LOCK(engine);
+		sfc_forced_lock_bit = GEN11_VECS_SFC_FORCED_LOCK_BIT;
+		break;
+
+	default:
+		return;
+	}
+
+	rmw_clear_fw(uncore, sfc_forced_lock, sfc_forced_lock_bit);
+}
+
+static int gen11_reset_engines(struct drm_i915_private *i915,
+			       intel_engine_mask_t engine_mask,
+			       unsigned int retry)
+{
+	const u32 hw_engine_mask[] = {
+		[RCS0]  = GEN11_GRDOM_RENDER,
+		[BCS0]  = GEN11_GRDOM_BLT,
+		[VCS0]  = GEN11_GRDOM_MEDIA,
+		[VCS1]  = GEN11_GRDOM_MEDIA2,
+		[VCS2]  = GEN11_GRDOM_MEDIA3,
+		[VCS3]  = GEN11_GRDOM_MEDIA4,
+		[VECS0] = GEN11_GRDOM_VECS,
+		[VECS1] = GEN11_GRDOM_VECS2,
+	};
+	struct intel_engine_cs *engine;
+	intel_engine_mask_t tmp;
+	u32 hw_mask;
+	int ret;
+
+	if (engine_mask == ALL_ENGINES) {
+		hw_mask = GEN11_GRDOM_FULL;
+	} else {
+		hw_mask = 0;
+		for_each_engine_masked(engine, i915, engine_mask, tmp) {
+			GEM_BUG_ON(engine->id >= ARRAY_SIZE(hw_engine_mask));
+			hw_mask |= hw_engine_mask[engine->id];
+			hw_mask |= gen11_lock_sfc(engine);
+		}
+	}
+
+	ret = gen6_hw_domain_reset(i915, hw_mask);
+
+	if (engine_mask != ALL_ENGINES)
+		for_each_engine_masked(engine, i915, engine_mask, tmp)
+			gen11_unlock_sfc(engine);
+
+	return ret;
+}
+
+static int gen8_engine_reset_prepare(struct intel_engine_cs *engine)
+{
+	struct intel_uncore *uncore = engine->uncore;
+	const i915_reg_t reg = RING_RESET_CTL(engine->mmio_base);
+	u32 request, mask, ack;
+	int ret;
+
+	ack = intel_uncore_read_fw(uncore, reg);
+	if (ack & RESET_CTL_CAT_ERROR) {
+		/*
+		 * For catastrophic errors, ready-for-reset sequence
+		 * needs to be bypassed: HAS#396813
+		 */
+		request = RESET_CTL_CAT_ERROR;
+		mask = RESET_CTL_CAT_ERROR;
+
+		/* Catastrophic errors need to be cleared by HW */
+		ack = 0;
+	} else if (!(ack & RESET_CTL_READY_TO_RESET)) {
+		request = RESET_CTL_REQUEST_RESET;
+		mask = RESET_CTL_READY_TO_RESET;
+		ack = RESET_CTL_READY_TO_RESET;
+	} else {
+		return 0;
+	}
+
+	intel_uncore_write_fw(uncore, reg, _MASKED_BIT_ENABLE(request));
+	ret = __intel_wait_for_register_fw(uncore, reg, mask, ack,
+					   700, 0, NULL);
+	if (ret)
+		DRM_ERROR("%s reset request timed out: {request: %08x, RESET_CTL: %08x}\n",
+			  engine->name, request,
+			  intel_uncore_read_fw(uncore, reg));
+
+	return ret;
+}
+
+static void gen8_engine_reset_cancel(struct intel_engine_cs *engine)
+{
+	intel_uncore_write_fw(engine->uncore,
+			      RING_RESET_CTL(engine->mmio_base),
+			      _MASKED_BIT_DISABLE(RESET_CTL_REQUEST_RESET));
+}
+
+static int gen8_reset_engines(struct drm_i915_private *i915,
+			      intel_engine_mask_t engine_mask,
+			      unsigned int retry)
+{
+	struct intel_engine_cs *engine;
+	const bool reset_non_ready = retry >= 1;
+	intel_engine_mask_t tmp;
+	int ret;
+
+	for_each_engine_masked(engine, i915, engine_mask, tmp) {
+		ret = gen8_engine_reset_prepare(engine);
+		if (ret && !reset_non_ready)
+			goto skip_reset;
+
+		/*
+		 * If this is not the first failed attempt to prepare,
+		 * we decide to proceed anyway.
+		 *
+		 * By doing so we risk context corruption and with
+		 * some gens (kbl), possible system hang if reset
+		 * happens during active bb execution.
+		 *
+		 * We rather take context corruption instead of
+		 * failed reset with a wedged driver/gpu. And
+		 * active bb execution case should be covered by
+		 * i915_stop_engines we have before the reset.
+		 */
+	}
+
+	if (INTEL_GEN(i915) >= 11)
+		ret = gen11_reset_engines(i915, engine_mask, retry);
+	else
+		ret = gen6_reset_engines(i915, engine_mask, retry);
+
+skip_reset:
+	for_each_engine_masked(engine, i915, engine_mask, tmp)
+		gen8_engine_reset_cancel(engine);
+
+	return ret;
+}
+
+typedef int (*reset_func)(struct drm_i915_private *,
+			  intel_engine_mask_t engine_mask,
+			  unsigned int retry);
+
+static reset_func intel_get_gpu_reset(struct drm_i915_private *i915)
+{
+	if (INTEL_GEN(i915) >= 8)
+		return gen8_reset_engines;
+	else if (INTEL_GEN(i915) >= 6)
+		return gen6_reset_engines;
+	else if (INTEL_GEN(i915) >= 5)
+		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,
+		    intel_engine_mask_t engine_mask)
+{
+	const int retries = engine_mask == ALL_ENGINES ? RESET_MAX_RETRIES : 1;
+	reset_func reset;
+	int ret = -ETIMEDOUT;
+	int retry;
+
+	reset = intel_get_gpu_reset(i915);
+	if (!reset)
+		return -ENODEV;
+
+	/*
+	 * If the power well sleeps during the reset, the reset
+	 * request may be dropped and never completes (causing -EIO).
+	 */
+	intel_uncore_forcewake_get(&i915->uncore, FORCEWAKE_ALL);
+	for (retry = 0; ret == -ETIMEDOUT && retry < retries; 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
+		 */
+		if (retry)
+			i915_stop_engines(i915, engine_mask);
+
+		GEM_TRACE("engine_mask=%x\n", engine_mask);
+		preempt_disable();
+		ret = reset(i915, engine_mask, retry);
+		preempt_enable();
+	}
+	intel_uncore_forcewake_put(&i915->uncore, FORCEWAKE_ALL);
+
+	return ret;
+}
+
+bool intel_has_gpu_reset(struct drm_i915_private *i915)
+{
+	if (!i915_modparams.reset)
+		return NULL;
+
+	return intel_get_gpu_reset(i915);
+}
+
+bool intel_has_reset_engine(struct drm_i915_private *i915)
+{
+	return INTEL_INFO(i915)->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->uncore, FORCEWAKE_ALL);
+	ret = gen6_hw_domain_reset(i915, guc_domain);
+	intel_uncore_forcewake_put(&i915->uncore, 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 void reset_prepare_engine(struct intel_engine_cs *engine)
+{
+	/*
+	 * 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->uncore, FORCEWAKE_ALL);
+	engine->reset.prepare(engine);
+}
+
+static void revoke_mmaps(struct drm_i915_private *i915)
+{
+	int i;
+
+	for (i = 0; i < i915->num_fence_regs; i++) {
+		struct drm_vma_offset_node *node;
+		struct i915_vma *vma;
+		u64 vma_offset;
+
+		vma = READ_ONCE(i915->fence_regs[i].vma);
+		if (!vma)
+			continue;
+
+		if (!i915_vma_has_userfault(vma))
+			continue;
+
+		GEM_BUG_ON(vma->fence != &i915->fence_regs[i]);
+		node = &vma->obj->base.vma_node;
+		vma_offset = vma->ggtt_view.partial.offset << PAGE_SHIFT;
+		unmap_mapping_range(i915->drm.anon_inode->i_mapping,
+				    drm_vma_node_offset_addr(node) + vma_offset,
+				    vma->size,
+				    1);
+	}
+}
+
+static void reset_prepare(struct drm_i915_private *i915)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	for_each_engine(engine, i915, id)
+		reset_prepare_engine(engine);
+
+	intel_uc_reset_prepare(i915);
+}
+
+static void gt_revoke(struct drm_i915_private *i915)
+{
+	revoke_mmaps(i915);
+}
+
+static int gt_reset(struct drm_i915_private *i915,
+		    intel_engine_mask_t stalled_mask)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	int err;
+
+	/*
+	 * Everything depends on having the GTT running, so we need to start
+	 * there.
+	 */
+	err = i915_ggtt_enable_hw(i915);
+	if (err)
+		return err;
+
+	for_each_engine(engine, i915, id)
+		intel_engine_reset(engine, stalled_mask & engine->mask);
+
+	i915_gem_restore_fences(i915);
+
+	return err;
+}
+
+static void reset_finish_engine(struct intel_engine_cs *engine)
+{
+	engine->reset.finish(engine);
+	intel_uncore_forcewake_put(engine->uncore, FORCEWAKE_ALL);
+}
+
+struct i915_gpu_restart {
+	struct work_struct work;
+	struct drm_i915_private *i915;
+};
+
+static void restart_work(struct work_struct *work)
+{
+	struct i915_gpu_restart *arg = container_of(work, typeof(*arg), work);
+	struct drm_i915_private *i915 = arg->i915;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	intel_wakeref_t wakeref;
+
+	wakeref = intel_runtime_pm_get(i915);
+	mutex_lock(&i915->drm.struct_mutex);
+	WRITE_ONCE(i915->gpu_error.restart, NULL);
+
+	for_each_engine(engine, i915, id) {
+		struct i915_request *rq;
+
+		/*
+		 * 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.
+		 */
+		if (!intel_engine_is_idle(engine))
+			continue;
+
+		rq = i915_request_alloc(engine, i915->kernel_context);
+		if (!IS_ERR(rq))
+			i915_request_add(rq);
+	}
+
+	mutex_unlock(&i915->drm.struct_mutex);
+	intel_runtime_pm_put(i915, wakeref);
+
+	kfree(arg);
+}
+
+static void reset_finish(struct drm_i915_private *i915)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	for_each_engine(engine, i915, id) {
+		reset_finish_engine(engine);
+		intel_engine_signal_breadcrumbs(engine);
+	}
+}
+
+static void reset_restart(struct drm_i915_private *i915)
+{
+	struct i915_gpu_restart *arg;
+
+	/*
+	 * Following the reset, ensure that we always reload context for
+	 * powersaving, and to correct engine->last_retired_context. Since
+	 * this requires us to submit a request, queue a worker to do that
+	 * task for us to evade any locking here.
+	 */
+	if (READ_ONCE(i915->gpu_error.restart))
+		return;
+
+	arg = kmalloc(sizeof(*arg), GFP_KERNEL);
+	if (arg) {
+		arg->i915 = i915;
+		INIT_WORK(&arg->work, restart_work);
+
+		WRITE_ONCE(i915->gpu_error.restart, arg);
+		queue_work(i915->wq, &arg->work);
+	}
+}
+
+static void nop_submit_request(struct i915_request *request)
+{
+	struct intel_engine_cs *engine = request->engine;
+	unsigned long flags;
+
+	GEM_TRACE("%s fence %llx:%lld -> -EIO\n",
+		  engine->name, request->fence.context, request->fence.seqno);
+	dma_fence_set_error(&request->fence, -EIO);
+
+	spin_lock_irqsave(&engine->timeline.lock, flags);
+	__i915_request_submit(request);
+	i915_request_mark_complete(request);
+	spin_unlock_irqrestore(&engine->timeline.lock, flags);
+
+	intel_engine_queue_breadcrumbs(engine);
+}
+
+static void __i915_gem_set_wedged(struct drm_i915_private *i915)
+{
+	struct i915_gpu_error *error = &i915->gpu_error;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	if (test_bit(I915_WEDGED, &error->flags))
+		return;
+
+	if (GEM_SHOW_DEBUG() && !intel_engines_are_idle(i915)) {
+		struct drm_printer p = drm_debug_printer(__func__);
+
+		for_each_engine(engine, i915, id)
+			intel_engine_dump(engine, &p, "%s\n", engine->name);
+	}
+
+	GEM_TRACE("start\n");
+
+	/*
+	 * 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).
+	 */
+	reset_prepare(i915);
+
+	/* Even if the GPU reset fails, it should still stop the engines */
+	if (!INTEL_INFO(i915)->gpu_reset_clobbers_display)
+		intel_gpu_reset(i915, ALL_ENGINES);
+
+	for_each_engine(engine, i915, id) {
+		engine->submit_request = nop_submit_request;
+		engine->schedule = NULL;
+	}
+	i915->caps.scheduler = 0;
+
+	/*
+	 * Make sure no request can slip through without getting completed by
+	 * either this call here to intel_engine_write_global_seqno, or the one
+	 * in nop_submit_request.
+	 */
+	synchronize_rcu_expedited();
+
+	/* Mark all executing requests as skipped */
+	for_each_engine(engine, i915, id)
+		engine->cancel_requests(engine);
+
+	reset_finish(i915);
+
+	smp_mb__before_atomic();
+	set_bit(I915_WEDGED, &error->flags);
+
+	GEM_TRACE("end\n");
+}
+
+void i915_gem_set_wedged(struct drm_i915_private *i915)
+{
+	struct i915_gpu_error *error = &i915->gpu_error;
+	intel_wakeref_t wakeref;
+
+	mutex_lock(&error->wedge_mutex);
+	with_intel_runtime_pm(i915, wakeref)
+		__i915_gem_set_wedged(i915);
+	mutex_unlock(&error->wedge_mutex);
+}
+
+static bool __i915_gem_unset_wedged(struct drm_i915_private *i915)
+{
+	struct i915_gpu_error *error = &i915->gpu_error;
+	struct i915_timeline *tl;
+
+	if (!test_bit(I915_WEDGED, &error->flags))
+		return true;
+
+	if (!i915->gt.scratch) /* Never full initialised, recovery impossible */
+		return false;
+
+	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.
+	 */
+	mutex_lock(&i915->gt.timelines.mutex);
+	list_for_each_entry(tl, &i915->gt.timelines.active_list, link) {
+		struct i915_request *rq;
+
+		rq = i915_active_request_get_unlocked(&tl->last_request);
+		if (!rq)
+			continue;
+
+		/*
+		 * All internal dependencies (i915_requests) will have
+		 * been flushed by the set-wedge, but we may be stuck waiting
+		 * for external fences. These should all be capped to 10s
+		 * (I915_FENCE_TIMEOUT) so this wait should not be unbounded
+		 * in the worst case.
+		 */
+		dma_fence_default_wait(&rq->fence, false, MAX_SCHEDULE_TIMEOUT);
+		i915_request_put(rq);
+	}
+	mutex_unlock(&i915->gt.timelines.mutex);
+
+	intel_engines_sanitize(i915, false);
+
+	/*
+	 * 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);
+
+	GEM_TRACE("end\n");
+
+	smp_mb__before_atomic(); /* complete takeover before enabling execbuf */
+	clear_bit(I915_WEDGED, &i915->gpu_error.flags);
+
+	return true;
+}
+
+bool i915_gem_unset_wedged(struct drm_i915_private *i915)
+{
+	struct i915_gpu_error *error = &i915->gpu_error;
+	bool result;
+
+	mutex_lock(&error->wedge_mutex);
+	result = __i915_gem_unset_wedged(i915);
+	mutex_unlock(&error->wedge_mutex);
+
+	return result;
+}
+
+static int do_reset(struct drm_i915_private *i915,
+		    intel_engine_mask_t stalled_mask)
+{
+	int err, i;
+
+	gt_revoke(i915);
+
+	err = intel_gpu_reset(i915, ALL_ENGINES);
+	for (i = 0; err && i < RESET_MAX_RETRIES; i++) {
+		msleep(10 * (i + 1));
+		err = intel_gpu_reset(i915, ALL_ENGINES);
+	}
+	if (err)
+		return err;
+
+	return gt_reset(i915, stalled_mask);
+}
+
+/**
+ * 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.
+ *
+ * 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,
+		intel_engine_mask_t stalled_mask,
+		const char *reason)
+{
+	struct i915_gpu_error *error = &i915->gpu_error;
+	int ret;
+
+	GEM_TRACE("flags=%lx\n", error->flags);
+
+	might_sleep();
+	assert_rpm_wakelock_held(i915);
+	GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, &error->flags));
+
+	/* Clear any previous failed attempts at recovery. Time to try again. */
+	if (!__i915_gem_unset_wedged(i915))
+		return;
+
+	if (reason)
+		dev_notice(i915->drm.dev, "Resetting chip for %s\n", reason);
+	error->reset_count++;
+
+	reset_prepare(i915);
+
+	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;
+	}
+
+	if (INTEL_INFO(i915)->gpu_reset_clobbers_display)
+		intel_runtime_pm_disable_interrupts(i915);
+
+	if (do_reset(i915, stalled_mask)) {
+		dev_err(i915->drm.dev, "Failed to reset chip\n");
+		goto taint;
+	}
+
+	if (INTEL_INFO(i915)->gpu_reset_clobbers_display)
+		intel_runtime_pm_enable_interrupts(i915);
+
+	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);
+	if (!__i915_wedged(error))
+		reset_restart(i915);
+	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);
+	goto finish;
+}
+
+static inline int intel_gt_reset_engine(struct drm_i915_private *i915,
+					struct intel_engine_cs *engine)
+{
+	return intel_gpu_reset(i915, engine->mask);
+}
+
+/**
+ * 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;
+	int ret;
+
+	GEM_TRACE("%s flags=%lx\n", engine->name, error->flags);
+	GEM_B