diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 0f2c22a3bcb6..35871c8a42a6 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -646,7 +646,7 @@ static void init_contexts(struct drm_i915_private *i915)
 
 static bool needs_preempt_context(struct drm_i915_private *i915)
 {
-	return HAS_EXECLISTS(i915);
+	return USES_GUC_SUBMISSION(i915);
 }
 
 int i915_gem_contexts_init(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 08049ee91cee..4c0e211c715d 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -13,6 +13,7 @@
 #include <linux/types.h>
 
 #include "i915_active_types.h"
+#include "i915_utils.h"
 #include "intel_engine_types.h"
 #include "intel_sseu.h"
 
@@ -38,6 +39,10 @@ struct intel_context {
 	struct i915_gem_context *gem_context;
 	struct intel_engine_cs *engine;
 	struct intel_engine_cs *inflight;
+#define intel_context_inflight(ce) ptr_mask_bits((ce)->inflight, 2)
+#define intel_context_inflight_count(ce)  ptr_unmask_bits((ce)->inflight, 2)
+#define intel_context_inflight_inc(ce) ptr_count_inc(&(ce)->inflight)
+#define intel_context_inflight_dec(ce) ptr_count_dec(&(ce)->inflight)
 
 	struct list_head signal_link;
 	struct list_head signals;
diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
index 2f1c6871ee95..9bb6ff76680e 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine.h
@@ -125,71 +125,26 @@ hangcheck_action_to_str(const enum intel_engine_hangcheck_action a)
 
 void intel_engines_set_scheduler_caps(struct drm_i915_private *i915);
 
-static inline void
-execlists_set_active(struct intel_engine_execlists *execlists,
-		     unsigned int bit)
-{
-	__set_bit(bit, (unsigned long *)&execlists->active);
-}
-
-static inline bool
-execlists_set_active_once(struct intel_engine_execlists *execlists,
-			  unsigned int bit)
-{
-	return !__test_and_set_bit(bit, (unsigned long *)&execlists->active);
-}
-
-static inline void
-execlists_clear_active(struct intel_engine_execlists *execlists,
-		       unsigned int bit)
-{
-	__clear_bit(bit, (unsigned long *)&execlists->active);
-}
-
-static inline void
-execlists_clear_all_active(struct intel_engine_execlists *execlists)
-{
-	execlists->active = 0;
-}
-
-static inline bool
-execlists_is_active(const struct intel_engine_execlists *execlists,
-		    unsigned int bit)
-{
-	return test_bit(bit, (unsigned long *)&execlists->active);
-}
-
-void execlists_user_begin(struct intel_engine_execlists *execlists,
-			  const struct execlist_port *port);
-void execlists_user_end(struct intel_engine_execlists *execlists);
-
-void
-execlists_cancel_port_requests(struct intel_engine_execlists * const execlists);
-
-struct i915_request *
-execlists_unwind_incomplete_requests(struct intel_engine_execlists *execlists);
-
 static inline unsigned int
 execlists_num_ports(const struct intel_engine_execlists * const execlists)
 {
 	return execlists->port_mask + 1;
 }
 
-static inline struct execlist_port *
-execlists_port_complete(struct intel_engine_execlists * const execlists,
-			struct execlist_port * const port)
+static inline struct i915_request *
+execlists_active(const struct intel_engine_execlists *execlists)
 {
-	const unsigned int m = execlists->port_mask;
-
-	GEM_BUG_ON(port_index(port, execlists) != 0);
-	GEM_BUG_ON(!execlists_is_active(execlists, EXECLISTS_ACTIVE_USER));
-
-	memmove(port, port + 1, m * sizeof(struct execlist_port));
-	memset(port + m, 0, sizeof(struct execlist_port));
-
-	return port;
+	GEM_BUG_ON(execlists->active - execlists->inflight >
+		   execlists_num_ports(execlists));
+	return READ_ONCE(*execlists->active);
 }
 
+void
+execlists_cancel_port_requests(struct intel_engine_execlists * const execlists);
+
+struct i915_request *
+execlists_unwind_incomplete_requests(struct intel_engine_execlists *execlists);
+
 static inline u32
 intel_read_status_page(const struct intel_engine_cs *engine, int reg)
 {
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
index 7fd33e81c2d9..d45328e254dc 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
@@ -508,6 +508,10 @@ void intel_engine_init_execlists(struct intel_engine_cs *engine)
 	GEM_BUG_ON(!is_power_of_2(execlists_num_ports(execlists)));
 	GEM_BUG_ON(execlists_num_ports(execlists) > EXECLIST_MAX_PORTS);
 
+	memset(execlists->pending, 0, sizeof(execlists->pending));
+	execlists->active =
+		memset(execlists->inflight, 0, sizeof(execlists->inflight));
+
 	execlists->queue_priority_hint = INT_MIN;
 	execlists->queue = RB_ROOT_CACHED;
 }
@@ -1152,7 +1156,7 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
 		return true;
 
 	/* Waiting to drain ELSP? */
-	if (READ_ONCE(engine->execlists.active)) {
+	if (execlists_active(&engine->execlists)) {
 		struct tasklet_struct *t = &engine->execlists.tasklet;
 
 		synchronize_hardirq(engine->i915->drm.irq);
@@ -1169,7 +1173,7 @@ bool intel_engine_is_idle(struct intel_engine_cs *engine)
 		/* Otherwise flush the tasklet if it was on another cpu */
 		tasklet_unlock_wait(t);
 
-		if (READ_ONCE(engine->execlists.active))
+		if (execlists_active(&engine->execlists))
 			return false;
 	}
 
@@ -1367,6 +1371,7 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine,
 	}
 
 	if (HAS_EXECLISTS(dev_priv)) {
+		struct i915_request * const *port, *rq;
 		const u32 *hws =
 			&engine->status_page.addr[I915_HWS_CSB_BUF0_INDEX];
 		const u8 num_entries = execlists->csb_size;
@@ -1399,27 +1404,33 @@ static void intel_engine_print_registers(struct intel_engine_cs *engine,
 		}
 
 		spin_lock_irqsave(&engine->active.lock, flags);
-		for (idx = 0; idx < execlists_num_ports(execlists); idx++) {
-			struct i915_request *rq;
-			unsigned int count;
+		for (port = execlists->active; (rq = *port); port++) {
+			char hdr[80];
+			int len;
+
+			len = snprintf(hdr, sizeof(hdr),
+				       "\t\tActive[%d: ",
+				       (int)(port - execlists->active));
+			if (!i915_request_signaled(rq))
+				len += snprintf(hdr + len, sizeof(hdr) - len,
+						"ring:{start:%08x, hwsp:%08x, seqno:%08x}, ",
+						i915_ggtt_offset(rq->ring->vma),
+						rq->timeline->hwsp_offset,
+						hwsp_seqno(rq));
+			snprintf(hdr + len, sizeof(hdr) - len, "rq: ");
+			print_request(m, rq, hdr);
+		}
+		for (port = execlists->pending; (rq = *port); port++) {
 			char hdr[80];
 
-			rq = port_unpack(&execlists->port[idx], &count);
-			if (!rq) {
-				drm_printf(m, "\t\tELSP[%d] idle\n", idx);
-			} else if (!i915_request_signaled(rq)) {
-				snprintf(hdr, sizeof(hdr),
-					 "\t\tELSP[%d] count=%d, ring:{start:%08x, hwsp:%08x, seqno:%08x}, rq: ",
-					 idx, count,
-					 i915_ggtt_offset(rq->ring->vma),
-					 rq->timeline->hwsp_offset,
-					 hwsp_seqno(rq));
-				print_request(m, rq, hdr);
-			} else {
-				print_request(m, rq, "\t\tELSP[%d] rq: ");
-			}
+			snprintf(hdr, sizeof(hdr),
+				 "\t\tPending[%d] ring:{start:%08x, hwsp:%08x, seqno:%08x}, rq: ",
+				 (int)(port - execlists->pending),
+				 i915_ggtt_offset(rq->ring->vma),
+				 rq->timeline->hwsp_offset,
+				 hwsp_seqno(rq));
+			print_request(m, rq, hdr);
 		}
-		drm_printf(m, "\t\tHW active? 0x%x\n", execlists->active);
 		spin_unlock_irqrestore(&engine->active.lock, flags);
 	} else if (INTEL_GEN(dev_priv) > 6) {
 		drm_printf(m, "\tPP_DIR_BASE: 0x%08x\n",
@@ -1583,15 +1594,19 @@ int intel_enable_engine_stats(struct intel_engine_cs *engine)
 	}
 
 	if (engine->stats.enabled++ == 0) {
-		const struct execlist_port *port = execlists->port;
-		unsigned int num_ports = execlists_num_ports(execlists);
+		struct i915_request * const *port;
+		struct i915_request *rq;
 
 		engine->stats.enabled_at = ktime_get();
 
 		/* XXX submission method oblivious? */
-		while (num_ports-- && port_isset(port)) {
+		for (port = execlists->active; (rq = *port); port++)
 			engine->stats.active++;
-			port++;
+
+		for (port = execlists->pending; (rq = *port); port++) {
+			/* Exclude any contexts already counted in active */
+			if (intel_context_inflight_count(rq->hw_context) == 1)
+				engine->stats.active++;
 		}
 
 		if (engine->stats.active)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_types.h b/drivers/gpu/drm/i915/gt/intel_engine_types.h
index 43e975a26016..b4f7b81a3c3e 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_engine_types.h
@@ -172,51 +172,28 @@ struct intel_engine_execlists {
 	 */
 	u32 __iomem *ctrl_reg;
 
-	/**
-	 * @port: execlist port states
-	 *
-	 * For each hardware ELSP (ExecList Submission Port) we keep
-	 * track of the last request and the number of times we submitted
-	 * that port to hw. We then count the number of times the hw reports
-	 * a context completion or preemption. As only one context can
-	 * be active on hw, we limit resubmission of context to port[0]. This
-	 * is called Lite Restore, of the context.
-	 */
-	struct execlist_port {
-		/**
-		 * @request_count: combined request and submission count
-		 */
-		struct i915_request *request_count;
-#define EXECLIST_COUNT_BITS 2
-#define port_request(p) ptr_mask_bits((p)->request_count, EXECLIST_COUNT_BITS)
-#define port_count(p) ptr_unmask_bits((p)->request_count, EXECLIST_COUNT_BITS)
-#define port_pack(rq, count) ptr_pack_bits(rq, count, EXECLIST_COUNT_BITS)
-#define port_unpack(p, count) ptr_unpack_bits((p)->request_count, count, EXECLIST_COUNT_BITS)
-#define port_set(p, packed) ((p)->request_count = (packed))
-#define port_isset(p) ((p)->request_count)
-#define port_index(p, execlists) ((p) - (execlists)->port)
-
-		/**
-		 * @context_id: context ID for port
-		 */
-		GEM_DEBUG_DECL(u32 context_id);
-
 #define EXECLIST_MAX_PORTS 2
-	} port[EXECLIST_MAX_PORTS];
-
 	/**
-	 * @active: is the HW active? We consider the HW as active after
-	 * submitting any context for execution and until we have seen the
-	 * last context completion event. After that, we do not expect any
-	 * more events until we submit, and so can park the HW.
-	 *
-	 * As we have a small number of different sources from which we feed
-	 * the HW, we track the state of each inside a single bitfield.
+	 * @active: the currently known context executing on HW
 	 */
-	unsigned int active;
-#define EXECLISTS_ACTIVE_USER 0
-#define EXECLISTS_ACTIVE_PREEMPT 1
-#define EXECLISTS_ACTIVE_HWACK 2
+	struct i915_request * const *active;
+	/**
+	 * @inflight: the set of contexts submitted and acknowleged by HW
+	 *
+	 * The set of inflight contexts is managed by reading CS events
+	 * from the HW. On a context-switch event (not preemption), we
+	 * know the HW has transitioned from port0 to port1, and we
+	 * advance our inflight/active tracking accordingly.
+	 */
+	struct i915_request *inflight[EXECLIST_MAX_PORTS + 1 /* sentinel */];
+	/**
+	 * @pending: the next set of contexts submitted to ELSP
+	 *
+	 * We store the array of contexts that we submit to HW (via ELSP) and
+	 * promote them to the inflight array once HW has signaled the
+	 * preemption or idle-to-active event.
+	 */
+	struct i915_request *pending[EXECLIST_MAX_PORTS + 1];
 
 	/**
 	 * @port_mask: number of execlist ports - 1
@@ -257,11 +234,6 @@ struct intel_engine_execlists {
 	 */
 	u32 *csb_status;
 
-	/**
-	 * @preempt_complete_status: expected CSB upon completing preemption
-	 */
-	u32 preempt_complete_status;
-
 	/**
 	 * @csb_size: context status buffer FIFO size
 	 */
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 82b7ace62d97..cb9d285bd00a 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -161,6 +161,8 @@
 #define GEN8_CTX_STATUS_COMPLETED_MASK \
 	 (GEN8_CTX_STATUS_COMPLETE | GEN8_CTX_STATUS_PREEMPTED)
 
+#define CTX_DESC_FORCE_RESTORE BIT_ULL(2)
+
 /* Typical size of the average request (2 pipecontrols and a MI_BB) */
 #define EXECLISTS_REQUEST_SIZE 64 /* bytes */
 #define WA_TAIL_DWORDS 2
@@ -221,6 +223,25 @@ static void execlists_init_reg_state(u32 *reg_state,
 				     struct intel_engine_cs *engine,
 				     struct intel_ring *ring);
 
+static inline u32 intel_hws_preempt_address(struct intel_engine_cs *engine)
+{
+	return (i915_ggtt_offset(engine->status_page.vma) +
+		I915_GEM_HWS_PREEMPT_ADDR);
+}
+
+static inline void
+ring_set_paused(const struct intel_engine_cs *engine, int state)
+{
+	/*
+	 * We inspect HWS_PREEMPT with a semaphore inside
+	 * engine->emit_fini_breadcrumb. If the dword is true,
+	 * the ring is paused as the semaphore will busywait
+	 * until the dword is false.
+	 */
+	engine->status_page.addr[I915_GEM_HWS_PREEMPT] = state;
+	wmb();
+}
+
 static inline struct i915_priolist *to_priolist(struct rb_node *rb)
 {
 	return rb_entry(rb, struct i915_priolist, node);
@@ -271,12 +292,6 @@ static inline bool need_preempt(const struct intel_engine_cs *engine,
 {
 	int last_prio;
 
-	if (!engine->preempt_context)
-		return false;
-
-	if (i915_request_completed(rq))
-		return false;
-
 	/*
 	 * Check if the current priority hint merits a preemption attempt.
 	 *
@@ -338,9 +353,6 @@ __maybe_unused static inline bool
 assert_priority_queue(const struct i915_request *prev,
 		      const struct i915_request *next)
 {
-	const struct intel_engine_execlists *execlists =
-		&prev->engine->execlists;
-
 	/*
 	 * Without preemption, the prev may refer to the still active element
 	 * which we refuse to let go.
@@ -348,7 +360,7 @@ assert_priority_queue(const struct i915_request *prev,
 	 * Even with preemption, there are times when we think it is better not
 	 * to preempt and leave an ostensibly lower priority request in flight.
 	 */
-	if (port_request(execlists->port) == prev)
+	if (i915_request_is_active(prev))
 		return true;
 
 	return rq_prio(prev) >= rq_prio(next);
@@ -442,13 +454,11 @@ __unwind_incomplete_requests(struct intel_engine_cs *engine)
 		struct intel_engine_cs *owner;
 
 		if (i915_request_completed(rq))
-			break;
+			continue; /* XXX */
 
 		__i915_request_unsubmit(rq);
 		unwind_wa_tail(rq);
 
-		GEM_BUG_ON(rq->hw_context->inflight);
-
 		/*
 		 * Push the request back into the queue for later resubmission.
 		 * If this request is not native to this physical engine (i.e.
@@ -500,32 +510,32 @@ execlists_context_status_change(struct i915_request *rq, unsigned long status)
 				   status, rq);
 }
 
-inline void
-execlists_user_begin(struct intel_engine_execlists *execlists,
-		     const struct execlist_port *port)
+static inline struct i915_request *
+execlists_schedule_in(struct i915_request *rq, int idx)
 {
-	execlists_set_active_once(execlists, EXECLISTS_ACTIVE_USER);
+	struct intel_context *ce = rq->hw_context;
+	int count;
+
+	trace_i915_request_in(rq, idx);
+
+	count = intel_context_inflight_count(ce);
+	if (!count) {
+		intel_context_get(ce);
+		ce->inflight = rq->engine;
+
+		execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_IN);
+		intel_engine_context_in(ce->inflight);
+	}
+
+	intel_context_inflight_inc(ce);
+	GEM_BUG_ON(intel_context_inflight(ce) != rq->engine);
+
+	return i915_request_get(rq);
 }
 
-inline void
-execlists_user_end(struct intel_engine_execlists *execlists)
+static void kick_siblings(struct i915_request *rq, struct intel_context *ce)
 {
-	execlists_clear_active(execlists, EXECLISTS_ACTIVE_USER);
-}
-
-static inline void
-execlists_context_schedule_in(struct i915_request *rq)
-{
-	GEM_BUG_ON(rq->hw_context->inflight);
-
-	execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_IN);
-	intel_engine_context_in(rq->engine);
-	rq->hw_context->inflight = rq->engine;
-}
-
-static void kick_siblings(struct i915_request *rq)
-{
-	struct virtual_engine *ve = to_virtual_engine(rq->hw_context->engine);
+	struct virtual_engine *ve = container_of(ce, typeof(*ve), context);
 	struct i915_request *next = READ_ONCE(ve->request);
 
 	if (next && next->execution_mask & ~rq->execution_mask)
@@ -533,30 +543,43 @@ static void kick_siblings(struct i915_request *rq)
 }
 
 static inline void
-execlists_context_schedule_out(struct i915_request *rq, unsigned long status)
-{
-	rq->hw_context->inflight = NULL;
-	intel_engine_context_out(rq->engine);
-	execlists_context_status_change(rq, status);
-	trace_i915_request_out(rq);
-
-	/*
-	 * If this is part of a virtual engine, its next request may have
-	 * been blocked waiting for access to the active context. We have
-	 * to kick all the siblings again in case we need to switch (e.g.
-	 * the next request is not runnable on this engine). Hopefully,
-	 * we will already have submitted the next request before the
-	 * tasklet runs and do not need to rebuild each virtual tree
-	 * and kick everyone again.
-	 */
-	if (rq->engine != rq->hw_context->engine)
-		kick_siblings(rq);
-}
-
-static u64 execlists_update_context(struct i915_request *rq)
+execlists_schedule_out(struct i915_request *rq)
 {
 	struct intel_context *ce = rq->hw_context;
 
+	GEM_BUG_ON(!intel_context_inflight_count(ce));
+
+	trace_i915_request_out(rq);
+
+	intel_context_inflight_dec(ce);
+	if (!intel_context_inflight_count(ce)) {
+		intel_engine_context_out(ce->inflight);
+		execlists_context_status_change(rq, INTEL_CONTEXT_SCHEDULE_OUT);
+
+		ce->inflight = NULL;
+		intel_context_put(ce);
+
+		/*
+		 * If this is part of a virtual engine, its next request may
+		 * have been blocked waiting for access to the active context.
+		 * We have to kick all the siblings again in case we need to
+		 * switch (e.g. the next request is not runnable on this
+		 * engine). Hopefully, we will already have submitted the next
+		 * request before the tasklet runs and do not need to rebuild
+		 * each virtual tree and kick everyone again.
+		 */
+		if (rq->engine != ce->engine)
+			kick_siblings(rq, ce);
+	}
+
+	i915_request_put(rq);
+}
+
+static u64 execlists_update_context(const struct i915_request *rq)
+{
+	struct intel_context *ce = rq->hw_context;
+	u64 desc;
+
 	ce->lrc_reg_state[CTX_RING_TAIL + 1] =
 		intel_ring_set_tail(rq->ring, rq->tail);
 
@@ -576,7 +599,11 @@ static u64 execlists_update_context(struct i915_request *rq)
 	 * wmb).
 	 */
 	mb();
-	return ce->lrc_desc;
+
+	desc = ce->lrc_desc;
+	ce->lrc_desc &= ~CTX_DESC_FORCE_RESTORE;
+
+	return desc;
 }
 
 static inline void write_desc(struct intel_engine_execlists *execlists, u64 desc, u32 port)
@@ -590,12 +617,62 @@ static inline void write_desc(struct intel_engine_execlists *execlists, u64 desc
 	}
 }
 
+static __maybe_unused void
+trace_ports(const struct intel_engine_execlists *execlists,
+	    const char *msg,
+	    struct i915_request * const *ports)
+{
+	const struct intel_engine_cs *engine =
+		container_of(execlists, typeof(*engine), execlists);
+
+	GEM_TRACE("%s: %s { %llx:%lld%s, %llx:%lld }\n",
+		  engine->name, msg,
+		  ports[0]->fence.context,
+		  ports[0]->fence.seqno,
+		  i915_request_completed(ports[0]) ? "!" :
+		  i915_request_started(ports[0]) ? "*" :
+		  "",
+		  ports[1] ? ports[1]->fence.context : 0,
+		  ports[1] ? ports[1]->fence.seqno : 0);
+}
+
+static __maybe_unused bool
+assert_pending_valid(const struct intel_engine_execlists *execlists,
+		     const char *msg)
+{
+	struct i915_request * const *port, *rq;
+	struct intel_context *ce = NULL;
+
+	trace_ports(execlists, msg, execlists->pending);
+
+	if (execlists->pending[execlists_num_ports(execlists)])
+		return false;
+
+	for (port = execlists->pending; (rq = *port); port++) {
+		if (ce == rq->hw_context)
+			return false;
+
+		ce = rq->hw_context;
+		if (i915_request_completed(rq))
+			continue;
+
+		if (i915_active_is_idle(&ce->active))
+			return false;
+
+		if (!i915_vma_is_pinned(ce->state))
+			return false;
+	}
+
+	return ce;
+}
+
 static void execlists_submit_ports(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists *execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
 	unsigned int n;
 
+	GEM_BUG_ON(!assert_pending_valid(execlists, "submit"));
+
 	/*
 	 * We can skip acquiring intel_runtime_pm_get() here as it was taken
 	 * on our behalf by the request (see i915_gem_mark_busy()) and it will
@@ -613,38 +690,16 @@ static void execlists_submit_ports(struct intel_engine_cs *engine)
 	 * of elsq entries, keep this in mind before changing the loop below.
 	 */
 	for (n = execlists_num_ports(execlists); n--; ) {
-		struct i915_request *rq;
-		unsigned int count;
-		u64 desc;
+		struct i915_request *rq = execlists->pending[n];
 
-		rq = port_unpack(&port[n], &count);
-		if (rq) {
-			GEM_BUG_ON(count > !n);
-			if (!count++)
-				execlists_context_schedule_in(rq);
-			port_set(&port[n], port_pack(rq, count));
-			desc = execlists_update_context(rq);
-			GEM_DEBUG_EXEC(port[n].context_id = upper_32_bits(desc));
-
-			GEM_TRACE("%s in[%d]:  ctx=%d.%d, fence %llx:%lld (current %d), prio=%d\n",
-				  engine->name, n,
-				  port[n].context_id, count,
-				  rq->fence.context, rq->fence.seqno,
-				  hwsp_seqno(rq),
-				  rq_prio(rq));
-		} else {
-			GEM_BUG_ON(!n);
-			desc = 0;
-		}
-
-		write_desc(execlists, desc, n);
+		write_desc(execlists,
+			   rq ? execlists_update_context(rq) : 0,
+			   n);
 	}
 
 	/* we need to manually load the submit queue */
 	if (execlists->ctrl_reg)
 		writel(EL_CTRL_LOAD, execlists->ctrl_reg);
-
-	execlists_clear_active(execlists, EXECLISTS_ACTIVE_HWACK);
 }
 
 static bool ctx_single_port_submission(const struct intel_context *ce)
@@ -668,6 +723,7 @@ static bool can_merge_ctx(const struct intel_context *prev,
 static bool can_merge_rq(const struct i915_request *prev,
 			 const struct i915_request *next)
 {
+	GEM_BUG_ON(prev == next);
 	GEM_BUG_ON(!assert_priority_queue(prev, next));
 
 	if (!can_merge_ctx(prev->hw_context, next->hw_context))
@@ -676,58 +732,6 @@ static bool can_merge_rq(const struct i915_request *prev,
 	return true;
 }
 
-static void port_assign(struct execlist_port *port, struct i915_request *rq)
-{
-	GEM_BUG_ON(rq == port_request(port));
-
-	if (port_isset(port))
-		i915_request_put(port_request(port));
-
-	port_set(port, port_pack(i915_request_get(rq), port_count(port)));
-}
-
-static void inject_preempt_context(struct intel_engine_cs *engine)
-{
-	struct intel_engine_execlists *execlists = &engine->execlists;
-	struct intel_context *ce = engine->preempt_context;
-	unsigned int n;
-
-	GEM_BUG_ON(execlists->preempt_complete_status !=
-		   upper_32_bits(ce->lrc_desc));
-
-	/*
-	 * Switch to our empty preempt context so
-	 * the state of the GPU is known (idle).
-	 */
-	GEM_TRACE("%s\n", engine->name);
-	for (n = execlists_num_ports(execlists); --n; )
-		write_desc(execlists, 0, n);
-
-	write_desc(execlists, ce->lrc_desc, n);
-
-	/* we need to manually load the submit queue */
-	if (execlists->ctrl_reg)
-		writel(EL_CTRL_LOAD, execlists->ctrl_reg);
-
-	execlists_clear_active(execlists, EXECLISTS_ACTIVE_HWACK);
-	execlists_set_active(execlists, EXECLISTS_ACTIVE_PREEMPT);
-
-	(void)I915_SELFTEST_ONLY(execlists->preempt_hang.count++);
-}
-
-static void complete_preempt_context(struct intel_engine_execlists *execlists)
-{
-	GEM_BUG_ON(!execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT));
-
-	if (inject_preempt_hang(execlists))
-		return;
-
-	execlists_cancel_port_requests(execlists);
-	__unwind_incomplete_requests(container_of(execlists,
-						  struct intel_engine_cs,
-						  execlists));
-}
-
 static void virtual_update_register_offsets(u32 *regs,
 					    struct intel_engine_cs *engine)
 {
@@ -792,7 +796,7 @@ static bool virtual_matches(const struct virtual_engine *ve,
 	 * we reuse the register offsets). This is a very small
 	 * hystersis on the greedy seelction algorithm.
 	 */
-	inflight = READ_ONCE(ve->context.inflight);
+	inflight = intel_context_inflight(&ve->context);
 	if (inflight && inflight != engine)
 		return false;
 
@@ -815,13 +819,23 @@ static void virtual_xfer_breadcrumbs(struct virtual_engine *ve,
 	spin_unlock(&old->breadcrumbs.irq_lock);
 }
 
+static struct i915_request *
+last_active(const struct intel_engine_execlists *execlists)
+{
+	struct i915_request * const *last = execlists->active;
+
+	while (*last && i915_request_completed(*last))
+		last++;
+
+	return *last;
+}
+
 static void execlists_dequeue(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
-	const struct execlist_port * const last_port =
-		&execlists->port[execlists->port_mask];
-	struct i915_request *last = port_request(port);
+	struct i915_request **port = execlists->pending;
+	struct i915_request ** const last_port = port + execlists->port_mask;
+	struct i915_request *last;
 	struct rb_node *rb;
 	bool submit = false;
 
@@ -867,65 +881,72 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 		break;
 	}
 
+	/*
+	 * If the queue is higher priority than the last
+	 * request in the currently active context, submit afresh.
+	 * We will resubmit again afterwards in case we need to split
+	 * the active context to interject the preemption request,
+	 * i.e. we will retrigger preemption following the ack in case
+	 * of trouble.
+	 */
+	last = last_active(execlists);
 	if (last) {
-		/*
-		 * Don't resubmit or switch until all outstanding
-		 * preemptions (lite-restore) are seen. Then we
-		 * know the next preemption status we see corresponds
-		 * to this ELSP update.
-		 */
-		GEM_BUG_ON(!execlists_is_active(execlists,
-						EXECLISTS_ACTIVE_USER));
-		GEM_BUG_ON(!port_count(&port[0]));
-
-		/*
-		 * If we write to ELSP a second time before the HW has had
-		 * a chance to respond to the previous write, we can confuse
-		 * the HW and hit "undefined behaviour". After writing to ELSP,
-		 * we must then wait until we see a context-switch event from
-		 * the HW to indicate that it has had a chance to respond.
-		 */
-		if (!execlists_is_active(execlists, EXECLISTS_ACTIVE_HWACK))
-			return;
-
 		if (need_preempt(engine, last, rb)) {
-			inject_preempt_context(engine);
-			return;
+			GEM_TRACE("%s: preempting last=%llx:%lld, prio=%d, hint=%d\n",
+				  engine->name,
+				  last->fence.context,
+				  last->fence.seqno,
+				  last->sched.attr.priority,
+				  execlists->queue_priority_hint);
+			/*
+			 * Don't let the RING_HEAD advance past the breadcrumb
+			 * as we unwind (and until we resubmit) so that we do
+			 * not accidentally tell it to go backwards.
+			 */
+			ring_set_paused(engine, 1);
+
+			/*
+			 * Note that we have not stopped the GPU at this point,
+			 * so we are unwinding the incomplete requests as they
+			 * remain inflight and so by the time we do complete
+			 * the preemption, some of the unwound requests may
+			 * complete!
+			 */
+			__unwind_incomplete_requests(engine);
+
+			/*
+			 * If we need to return to the preempted context, we
+			 * need to skip the lite-restore and force it to
+			 * reload the RING_TAIL. Otherwise, the HW has a
+			 * tendency to ignore us rewinding the TAIL to the
+			 * end of an earlier request.
+			 */
+			last->hw_context->lrc_desc |= CTX_DESC_FORCE_RESTORE;
+			last = NULL;
+		} else {
+			/*
+			 * Otherwise if we already have a request pending
+			 * for execution after the current one, we can
+			 * just wait until the next CS event before
+			 * queuing more. In either case we will force a
+			 * lite-restore preemption event, but if we wait
+			 * we hopefully coalesce several updates into a single
+			 * submission.
+			 */
+			if (!list_is_last(&last->sched.link,
+					  &engine->active.requests))
+				return;
+
+			/*
+			 * WaIdleLiteRestore:bdw,skl
+			 * Apply the wa NOOPs to prevent
+			 * ring:HEAD == rq:TAIL as we resubmit the
+			 * request. See gen8_emit_fini_breadcrumb() for
+			 * where we prepare the padding after the
+			 * end of the request.
+			 */
+			last->tail = last->wa_tail;
 		}
-
-		/*
-		 * In theory, we could coalesce more requests onto
-		 * the second port (the first port is active, with
-		 * no preemptions pending). However, that means we
-		 * then have to deal with the possible lite-restore
-		 * of the second port (as we submit the ELSP, there
-		 * may be a context-switch) but also we may complete
-		 * the resubmission before the context-switch. Ergo,
-		 * coalescing onto the second port will cause a
-		 * preemption event, but we cannot predict whether
-		 * that will affect port[0] or port[1].
-		 *
-		 * If the second port is already active, we can wait
-		 * until the next context-switch before contemplating
-		 * new requests. The GPU will be busy and we should be
-		 * able to resubmit the new ELSP before it idles,
-		 * avoiding pipeline bubbles (momentary pauses where
-		 * the driver is unable to keep up the supply of new
-		 * work). However, we have to double check that the
-		 * priorities of the ports haven't been switch.
-		 */
-		if (port_count(&port[1]))
-			return;
-
-		/*
-		 * WaIdleLiteRestore:bdw,skl
-		 * Apply the wa NOOPs to prevent
-		 * ring:HEAD == rq:TAIL as we resubmit the
-		 * request. See gen8_emit_fini_breadcrumb() for
-		 * where we prepare the padding after the
-		 * end of the request.
-		 */
-		last->tail = last->wa_tail;
 	}
 
 	while (rb) { /* XXX virtual is always taking precedence */
@@ -955,9 +976,24 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 				continue;
 			}
 
+			if (i915_request_completed(rq)) {
+				ve->request = NULL;
+				ve->base.execlists.queue_priority_hint = INT_MIN;
+				rb_erase_cached(rb, &execlists->virtual);
+				RB_CLEAR_NODE(rb);
+
+				rq->engine = engine;
+				__i915_request_submit(rq);
+
+				spin_unlock(&ve->base.active.lock);
+
+				rb = rb_first_cached(&execlists->virtual);
+				continue;
+			}
+
 			if (last && !can_merge_rq(last, rq)) {
 				spin_unlock(&ve->base.active.lock);
-				return; /* leave this rq for another engine */
+				return; /* leave this for another */
 			}
 
 			GEM_TRACE("%s: virtual rq=%llx:%lld%s, new engine? %s\n",
@@ -1006,9 +1042,10 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 			}
 
 			__i915_request_submit(rq);
-			trace_i915_request_in(rq, port_index(port, execlists));
-			submit = true;
-			last = rq;
+			if (!i915_request_completed(rq)) {
+				submit = true;
+				last = rq;
+			}
 		}
 
 		spin_unlock(&ve->base.active.lock);
@@ -1021,6 +1058,9 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 		int i;
 
 		priolist_for_each_request_consume(rq, rn, p, i) {
+			if (i915_request_completed(rq))
+				goto skip;
+
 			/*
 			 * Can we combine this request with the current port?
 			 * It has to be the same context/ringbuffer and not
@@ -1060,19 +1100,14 @@ static void execlists_dequeue(struct intel_engine_cs *engine)
 				    ctx_single_port_submission(rq->hw_context))
 					goto done;
 
-
-				if (submit)
-					port_assign(port, last);
+				*port = execlists_schedule_in(last, port - execlists->pending);
 				port++;
-
-				GEM_BUG_ON(port_isset(port));
 			}
 
-			__i915_request_submit(rq);
-			trace_i915_request_in(rq, port_index(port, execlists));
-
 			last = rq;
 			submit = true;
+skip:
+			__i915_request_submit(rq);
 		}
 
 		rb_erase_cached(&p->node, &execlists->queue);
@@ -1097,54 +1132,30 @@ done:
 	 * interrupt for secondary ports).
 	 */
 	execlists->queue_priority_hint = queue_prio(execlists);
+	GEM_TRACE("%s: queue_priority_hint:%d, submit:%s\n",
+		  engine->name, execlists->queue_priority_hint,
+		  yesno(submit));
 
 	if (submit) {
-		port_assign(port, last);
+		*port = execlists_schedule_in(last, port - execlists->pending);
+		memset(port + 1, 0, (last_port - port) * sizeof(*port));
 		execlists_submit_ports(engine);
 	}
-
-	/* We must always keep the beast fed if we have work piled up */
-	GEM_BUG_ON(rb_first_cached(&execlists->queue) &&
-		   !port_isset(execlists->port));
-
-	/* Re-evaluate the executing context setup after each preemptive kick */
-	if (last)
-		execlists_user_begin(execlists, execlists->port);
-
-	/* If the engine is now idle, so should be the flag; and vice versa. */
-	GEM_BUG_ON(execlists_is_active(&engine->execlists,
-				       EXECLISTS_ACTIVE_USER) ==
-		   !port_isset(engine->execlists.port));
 }
 
 void
 execlists_cancel_port_requests(struct intel_engine_execlists * const execlists)
 {
-	struct execlist_port *port = execlists->port;
-	unsigned int num_ports = execlists_num_ports(execlists);
+	struct i915_request * const *port, *rq;
 
-	while (num_ports-- && port_isset(port)) {
-		struct i915_request *rq = port_request(port);
+	for (port = execlists->pending; (rq = *port); port++)
+		execlists_schedule_out(rq);
+	memset(execlists->pending, 0, sizeof(execlists->pending));
 
-		GEM_TRACE("%s:port%u fence %llx:%lld, (current %d)\n",
-			  rq->engine->name,
-			  (unsigned int)(port - execlists->port),
-			  rq->fence.context, rq->fence.seqno,
-			  hwsp_seqno(rq));
-
-		GEM_BUG_ON(!execlists->active);
-		execlists_context_schedule_out(rq,
-					       i915_request_completed(rq) ?
-					       INTEL_CONTEXT_SCHEDULE_OUT :
-					       INTEL_CONTEXT_SCHEDULE_PREEMPTED);
-
-		i915_request_put(rq);
-
-		memset(port, 0, sizeof(*port));
-		port++;
-	}
-
-	execlists_clear_all_active(execlists);
+	for (port = execlists->active; (rq = *port); port++)
+		execlists_schedule_out(rq);
+	execlists->active =
+		memset(execlists->inflight, 0, sizeof(execlists->inflight));
 }
 
 static inline void
@@ -1163,7 +1174,6 @@ reset_in_progress(const struct intel_engine_execlists *execlists)
 static void process_csb(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
 	const u32 * const buf = execlists->csb_status;
 	const u8 num_entries = execlists->csb_size;
 	u8 head, tail;
@@ -1198,9 +1208,7 @@ static void process_csb(struct intel_engine_cs *engine)
 	rmb();
 
 	do {
-		struct i915_request *rq;
 		unsigned int status;
-		unsigned int count;
 
 		if (++head == num_entries)
 			head = 0;
@@ -1223,68 +1231,38 @@ static void process_csb(struct intel_engine_cs *engine)
 		 * status notifier.
 		 */
 
-		GEM_TRACE("%s csb[%d]: status=0x%08x:0x%08x, active=0x%x\n",
+		GEM_TRACE("%s csb[%d]: status=0x%08x:0x%08x\n",
 			  engine->name, head,
-			  buf[2 * head + 0], buf[2 * head + 1],
-			  execlists->active);
+			  buf[2 * head + 0], buf[2 * head + 1]);
 
 		status = buf[2 * head];
-		if (status & (GEN8_CTX_STATUS_IDLE_ACTIVE |
-			      GEN8_CTX_STATUS_PREEMPTED))
-			execlists_set_active(execlists,
-					     EXECLISTS_ACTIVE_HWACK);
-		if (status & GEN8_CTX_STATUS_ACTIVE_IDLE)
-			execlists_clear_active(execlists,
-					       EXECLISTS_ACTIVE_HWACK);
+		if (status & GEN8_CTX_STATUS_IDLE_ACTIVE) {
+			GEM_BUG_ON(*execlists->active);
+promote:
+			GEM_BUG_ON(!assert_pending_valid(execlists, "promote"));
+			execlists->active =
+				memcpy(execlists->inflight,
+				       execlists->pending,
+				       execlists_num_ports(execlists) *
+				       sizeof(*execlists->pending));
+			execlists->pending[0] = NULL;
 
-		if (!(status & GEN8_CTX_STATUS_COMPLETED_MASK))
-			continue;
+			if (!inject_preempt_hang(execlists))
+				ring_set_paused(engine, 0);
+		} else if (status & GEN8_CTX_STATUS_PREEMPTED) {
+			struct i915_request * const *port = execlists->active;
 
-		/* We should never get a COMPLETED | IDLE_ACTIVE! */
-		GEM_BUG_ON(status & GEN8_CTX_STATUS_IDLE_ACTIVE);
+			trace_ports(execlists, "preempted", execlists->active);
 
-		if (status & GEN8_CTX_STATUS_COMPLETE &&
-		    buf[2*head + 1] == execlists->preempt_complete_status) {
-			GEM_TRACE("%s preempt-idle\n", engine->name);
-			complete_preempt_context(execlists);
-			continue;
-		}
+			while (*port)
+				execlists_schedule_out(*port++);
 
-		if (status & GEN8_CTX_STATUS_PREEMPTED &&
-		    execlists_is_active(execlists,
-					EXECLISTS_ACTIVE_PREEMPT))
-			continue;
+			goto promote;
+		} else if (*execlists->active) {
+			struct i915_request *rq = *execlists->active++;
 
-		GEM_BUG_ON(!execlists_is_active(execlists,
-						EXECLISTS_ACTIVE_USER));
-
-		rq = port_unpack(port, &count);
-		GEM_TRACE("%s out[0]: ctx=%d.%d, fence %llx:%lld (current %d), prio=%d\n",
-			  engine->name,
-			  port->context_id, count,
-			  rq ? rq->fence.context : 0,
-			  rq ? rq->fence.seqno : 0,
-			  rq ? hwsp_seqno(rq) : 0,
-			  rq ? rq_prio(rq) : 0);
-
-		/* Check the context/desc id for this event matches */
-		GEM_DEBUG_BUG_ON(buf[2 * head + 1] != port->context_id);
-
-		GEM_BUG_ON(count == 0);
-		if (--count == 0) {
-			/*
-			 * On the final event corresponding to the
-			 * submission of this context, we expect either
-			 * an element-switch event or a completion
-			 * event (and on completion, the active-idle
-			 * marker). No more preemptions, lite-restore
-			 * or otherwise.
-			 */
-			GEM_BUG_ON(status & GEN8_CTX_STATUS_PREEMPTED);
-			GEM_BUG_ON(port_isset(&port[1]) &&
-				   !(status & GEN8_CTX_STATUS_ELEMENT_SWITCH));
-			GEM_BUG_ON(!port_isset(&port[1]) &&
-				   !(status & GEN8_CTX_STATUS_ACTIVE_IDLE));
+			trace_ports(execlists, "completed",
+				    execlists->active - 1);
 
 			/*
 			 * We rely on the hardware being strongly
@@ -1293,21 +1271,10 @@ static void process_csb(struct intel_engine_cs *engine)
 			 * user interrupt and CSB is processed.
 			 */
 			GEM_BUG_ON(!i915_request_completed(rq));
+			execlists_schedule_out(rq);
 
-			execlists_context_schedule_out(rq,
-						       INTEL_CONTEXT_SCHEDULE_OUT);
-			i915_request_put(rq);
-
-			GEM_TRACE("%s completed ctx=%d\n",
-				  engine->name, port->context_id);
-
-			port = execlists_port_complete(execlists, port);
-			if (port_isset(port))
-				execlists_user_begin(execlists, port);
-			else
-				execlists_user_end(execlists);
-		} else {
-			port_set(port, port_pack(rq, count));
+			GEM_BUG_ON(execlists->active - execlists->inflight >
+				   execlists_num_ports(execlists));
 		}
 	} while (head != tail);
 
@@ -1332,7 +1299,7 @@ static void __execlists_submission_tasklet(struct intel_engine_cs *const engine)
 	lockdep_assert_held(&engine->active.lock);
 
 	process_csb(engine);
-	if (!execlists_is_active(&engine->execlists, EXECLISTS_ACTIVE_PREEMPT))
+	if (!engine->execlists.pending[0])
 		execlists_dequeue(engine);
 }
 
@@ -1345,11 +1312,6 @@ static void execlists_submission_tasklet(unsigned long data)
 	struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
 	unsigned long flags;
 
-	GEM_TRACE("%s awake?=%d, active=%x\n",
-		  engine->name,
-		  !!intel_wakeref_active(&engine->wakeref),
-		  engine->execlists.active);
-
 	spin_lock_irqsave(&engine->active.lock, flags);
 	__execlists_submission_tasklet(engine);
 	spin_unlock_irqrestore(&engine->active.lock, flags);
@@ -1376,12 +1338,16 @@ static void __submit_queue_imm(struct intel_engine_cs *engine)
 		tasklet_hi_schedule(&execlists->tasklet);
 }
 
-static void submit_queue(struct intel_engine_cs *engine, int prio)
+static void submit_queue(struct intel_engine_cs *engine,
+			 const struct i915_request *rq)
 {
-	if (prio > engine->execlists.queue_priority_hint) {
-		engine->execlists.queue_priority_hint = prio;
-		__submit_queue_imm(engine);
-	}
+	struct intel_engine_execlists *execlists = &engine->execlists;
+
+	if (rq_prio(rq) <= execlists->queue_priority_hint)
+		return;
+
+	execlists->queue_priority_hint = rq_prio(rq);
+	__submit_queue_imm(engine);
 }
 
 static void execlists_submit_request(struct i915_request *request)
@@ -1397,7 +1363,7 @@ static void execlists_submit_request(struct i915_request *request)
 	GEM_BUG_ON(RB_EMPTY_ROOT(&engine->execlists.queue.rb_root));
 	GEM_BUG_ON(list_empty(&request->sched.link));
 
-	submit_queue(engine, rq_prio(request));
+	submit_queue(engine, request);
 
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
@@ -2048,27 +2014,13 @@ static void execlists_reset_prepare(struct intel_engine_cs *engine)
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
 
-static bool lrc_regs_ok(const struct i915_request *rq)
-{
-	const struct intel_ring *ring = rq->ring;
-	const u32 *regs = rq->hw_context->lrc_reg_state;
-
-	/* Quick spot check for the common signs of context corruption */
-
-	if (regs[CTX_RING_BUFFER_CONTROL + 1] !=
-	    (RING_CTL_SIZE(ring->size) | RING_VALID))
-		return false;
-
-	if (regs[CTX_RING_BUFFER_START + 1] != i915_ggtt_offset(ring->vma))
-		return false;
-
-	return true;
-}
-
-static void reset_csb_pointers(struct intel_engine_execlists *execlists)
+static void reset_csb_pointers(struct intel_engine_cs *engine)
 {
+	struct intel_engine_execlists * const execlists = &engine->execlists;
 	const unsigned int reset_value = execlists->csb_size - 1;
 
+	ring_set_paused(engine, 0);
+
 	/*
 	 * After a reset, the HW starts writing into CSB entry [0]. We
 	 * therefore have to set our HEAD pointer back one entry so that
@@ -2115,18 +2067,21 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	process_csb(engine); /* drain preemption events */
 
 	/* Following the reset, we need to reload the CSB read/write pointers */
-	reset_csb_pointers(&engine->execlists);
+	reset_csb_pointers(engine);
 
 	/*
 	 * Save the currently executing context, even if we completed
 	 * its request, it was still running at the time of the
 	 * reset and will have been clobbered.
 	 */
-	if (!port_isset(execlists->port))
-		goto out_clear;
+	rq = execlists_active(execlists);
+	if (!rq)
+		return;
 
-	rq = port_request(execlists->port);
 	ce = rq->hw_context;
+	GEM_BUG_ON(i915_active_is_idle(&ce->active));
+	GEM_BUG_ON(!i915_vma_is_pinned(ce->state));
+	rq = active_request(rq);
 
 	/*
 	 * Catch up with any missed context-switch interrupts.
@@ -2139,9 +2094,12 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	 */
 	execlists_cancel_port_requests(execlists);
 
-	rq = active_request(rq);
-	if (!rq)
+	if (!rq) {
+		ce->ring->head = ce->ring->tail;
 		goto out_replay;
+	}
+
+	ce->ring->head = intel_ring_wrap(ce->ring, rq->head);
 
 	/*
 	 * If this request hasn't started yet, e.g. it is waiting on a
@@ -2155,7 +2113,7 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	 * Otherwise, if we have not started yet, the request should replay
 	 * perfectly and we do not need to flag the result as being erroneous.
 	 */
-	if (!i915_request_started(rq) && lrc_regs_ok(rq))
+	if (!i915_request_started(rq))
 		goto out_replay;
 
 	/*
@@ -2170,7 +2128,7 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	 * image back to the expected values to skip over the guilty request.
 	 */
 	i915_reset_request(rq, stalled);
-	if (!stalled && lrc_regs_ok(rq))
+	if (!stalled)
 		goto out_replay;
 
 	/*
@@ -2190,17 +2148,13 @@ static void __execlists_reset(struct intel_engine_cs *engine, bool stalled)
 	execlists_init_reg_state(regs, ce, engine, ce->ring);
 
 out_replay:
-	/* Rerun the request; its payload has been neutered (if guilty). */
-	ce->ring->head =
-		rq ? intel_ring_wrap(ce->ring, rq->head) : ce->ring->tail;
+	GEM_TRACE("%s replay {head:%04x, tail:%04x\n",
+		  engine->name, ce->ring->head, ce->ring->tail);
 	intel_ring_update_space(ce->ring);
 	__execlists_update_reg_state(ce, engine);
 
 	/* Push back any incomplete requests for replay after the reset. */
 	__unwind_incomplete_requests(engine);
-
-out_clear:
-	execlists_clear_all_active(execlists);
 }
 
 static void execlists_reset(struct intel_engine_cs *engine, bool stalled)
@@ -2296,7 +2250,6 @@ static void execlists_cancel_requests(struct intel_engine_cs *engine)
 
 	execlists->queue_priority_hint = INT_MIN;
 	execlists->queue = RB_ROOT_CACHED;
-	GEM_BUG_ON(port_isset(execlists->port));
 
 	GEM_BUG_ON(__tasklet_is_enabled(&execlists->tasklet));
 	execlists->tasklet.func = nop_submission_tasklet;
@@ -2514,15 +2467,29 @@ static u32 *gen8_emit_wa_tail(struct i915_request *request, u32 *cs)
 	return cs;
 }
 
+static u32 *emit_preempt_busywait(struct i915_request *request, u32 *cs)
+{
+	*cs++ = MI_SEMAPHORE_WAIT |
+		MI_SEMAPHORE_GLOBAL_GTT |
+		MI_SEMAPHORE_POLL |
+		MI_SEMAPHORE_SAD_EQ_SDD;
+	*cs++ = 0;
+	*cs++ = intel_hws_preempt_address(request->engine);
+	*cs++ = 0;
+
+	return cs;
+}
+
 static u32 *gen8_emit_fini_breadcrumb(struct i915_request *request, u32 *cs)
 {
 	cs = gen8_emit_ggtt_write(cs,
 				  request->fence.seqno,
 				  request->timeline->hwsp_offset,
 				  0);
-
 	*cs++ = MI_USER_INTERRUPT;
+
 	*cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
+	cs = emit_preempt_busywait(request, cs);
 
 	request->tail = intel_ring_offset(request, cs);
 	assert_ring_tail_valid(request->ring, request->tail);
@@ -2543,9 +2510,10 @@ static u32 *gen8_emit_fini_breadcrumb_rcs(struct i915_request *request, u32 *cs)
 				    PIPE_CONTROL_FLUSH_ENABLE |
 				    PIPE_CONTROL_CS_STALL,
 				    0);
-
 	*cs++ = MI_USER_INTERRUPT;
+
 	*cs++ = MI_ARB_ON_OFF | MI_ARB_ENABLE;
+	cs = emit_preempt_busywait(request, cs);
 
 	request->tail = intel_ring_offset(request, cs);
 	assert_ring_tail_valid(request->ring, request->tail);
@@ -2594,8 +2562,7 @@ void intel_execlists_set_default_submission(struct intel_engine_cs *engine)
 	engine->flags |= I915_ENGINE_SUPPORTS_STATS;
 	if (!intel_vgpu_active(engine->i915))
 		engine->flags |= I915_ENGINE_HAS_SEMAPHORES;
-	if (engine->preempt_context &&
-	    HAS_LOGICAL_RING_PREEMPTION(engine->i915))
+	if (HAS_LOGICAL_RING_PREEMPTION(engine->i915))
 		engine->flags |= I915_ENGINE_HAS_PREEMPTION;
 }
 
@@ -2718,11 +2685,6 @@ int intel_execlists_submission_init(struct intel_engine_cs *engine)
 			i915_mmio_reg_offset(RING_ELSP(base));
 	}
 
-	execlists->preempt_complete_status = ~0u;
-	if (engine->preempt_context)
-		execlists->preempt_complete_status =
-			upper_32_bits(engine->preempt_context->lrc_desc);
-
 	execlists->csb_status =
 		&engine->status_page.addr[I915_HWS_CSB_BUF0_INDEX];
 
@@ -2734,7 +2696,7 @@ int intel_execlists_submission_init(struct intel_engine_cs *engine)
 	else
 		execlists->csb_size = GEN11_CSB_ENTRIES;
 
-	reset_csb_pointers(execlists);
+	reset_csb_pointers(engine);
 
 	return 0;
 }
@@ -2917,11 +2879,6 @@ populate_lr_context(struct intel_context *ce,
 	if (!engine->default_state)
 		regs[CTX_CONTEXT_CONTROL + 1] |=
 			_MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT);
-	if (ce->gem_context == engine->i915->preempt_context &&
-	    INTEL_GEN(engine->i915) < 11)
-		regs[CTX_CONTEXT_CONTROL + 1] |=
-			_MASKED_BIT_ENABLE(CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT |
-					   CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT);
 
 	ret = 0;
 err_unpin_ctx:
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index b7e9fddef270..a497cf7acb6a 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1248,10 +1248,10 @@ static void error_record_engine_registers(struct i915_gpu_state *error,
 	}
 }
 
-static void record_request(struct i915_request *request,
+static void record_request(const struct i915_request *request,
 			   struct drm_i915_error_request *erq)
 {
-	struct i915_gem_context *ctx = request->gem_context;
+	const struct i915_gem_context *ctx = request->gem_context;
 
 	erq->flags = request->fence.flags;
 	erq->context = request->fence.context;
@@ -1315,20 +1315,15 @@ static void engine_record_requests(struct intel_engine_cs *engine,
 	ee->num_requests = count;
 }
 
-static void error_record_engine_execlists(struct intel_engine_cs *engine,
+static void error_record_engine_execlists(const struct intel_engine_cs *engine,
 					  struct drm_i915_error_engine *ee)
 {
 	const struct intel_engine_execlists * const execlists = &engine->execlists;
-	unsigned int n;
+	struct i915_request * const *port = execlists->active;
+	unsigned int n = 0;
 
-	for (n = 0; n < execlists_num_ports(execlists); n++) {
-		struct i915_request *rq = port_request(&execlists->port[n]);
-
-		if (!rq)
-			break;
-
-		record_request(rq, &ee->execlist[n]);
-	}
+	while (*port)
+		record_request(*port++, &ee->execlist[n++]);
 
 	ee->num_ports = n;
 }
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 7083e6ab92c5..0c99694faab7 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -276,6 +276,12 @@ static bool i915_request_retire(struct i915_request *rq)
 
 	local_irq_disable();
 
+	/*
+	 * We only loosely track inflight requests across preemption,
+	 * and so we may find ourselves attempting to retire a _completed_
+	 * request that we have removed from the HW and put back on a run
+	 * queue.
+	 */
 	spin_lock(&rq->engine->active.lock);
 	list_del(&rq->sched.link);
 	spin_unlock(&rq->engine->active.lock);
diff --git a/drivers/gpu/drm/i915/i915_request.h b/drivers/gpu/drm/i915/i915_request.h
index edbbdfec24ab..bebc1e9b4a5e 100644
--- a/drivers/gpu/drm/i915/i915_request.h
+++ b/drivers/gpu/drm/i915/i915_request.h
@@ -28,6 +28,7 @@
 #include <linux/dma-fence.h>
 #include <linux/lockdep.h>
 
+#include "gt/intel_context_types.h"
 #include "gt/intel_engine_types.h"
 
 #include "i915_gem.h"
diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
index 2e9b38bdc33c..b1ba3e65cd52 100644
--- a/drivers/gpu/drm/i915/i915_scheduler.c
+++ b/drivers/gpu/drm/i915/i915_scheduler.c
@@ -179,8 +179,7 @@ static inline int rq_prio(const struct i915_request *rq)
 
 static void kick_submission(struct intel_engine_cs *engine, int prio)
 {
-	const struct i915_request *inflight =
-		port_request(engine->execlists.port);
+	const struct i915_request *inflight = *engine->execlists.active;
 
 	/*
 	 * If we are already the currently executing context, don't
diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 2987219a6300..4920ff9aba62 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -131,6 +131,18 @@ __check_struct_size(size_t base, size_t arr, size_t count, size_t *size)
 	((typeof(ptr))((unsigned long)(ptr) | __bits));			\
 })
 
+#define ptr_count_dec(p_ptr) do {					\
+	typeof(p_ptr) __p = (p_ptr);					\
+	unsigned long __v = (unsigned long)(*__p);			\
+	*__p = (typeof(*p_ptr))(--__v);					\
+} while (0)
+
+#define ptr_count_inc(p_ptr) do {					\
+	typeof(p_ptr) __p = (p_ptr);					\
+	unsigned long __v = (unsigned long)(*__p);			\
+	*__p = (typeof(*p_ptr))(++__v);					\
+} while (0)
+
 #define page_mask_bits(ptr) ptr_mask_bits(ptr, PAGE_SHIFT)
 #define page_unmask_bits(ptr) ptr_unmask_bits(ptr, PAGE_SHIFT)
 #define page_pack_bits(ptr, bits) ptr_pack_bits(ptr, bits, PAGE_SHIFT)
diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
index db531ebc7704..12c22359fdac 100644
--- a/drivers/gpu/drm/i915/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/intel_guc_submission.c
@@ -32,7 +32,11 @@
 #include "intel_guc_submission.h"
 #include "i915_drv.h"
 
-#define GUC_PREEMPT_FINISHED		0x1
+enum {
+	GUC_PREEMPT_NONE = 0,
+	GUC_PREEMPT_INPROGRESS,
+	GUC_PREEMPT_FINISHED,
+};
 #define GUC_PREEMPT_BREADCRUMB_DWORDS	0x8
 #define GUC_PREEMPT_BREADCRUMB_BYTES	\
 	(sizeof(u32) * GUC_PREEMPT_BREADCRUMB_DWORDS)
@@ -537,15 +541,11 @@ static void guc_add_request(struct intel_guc *guc, struct i915_request *rq)
 	u32 ctx_desc = lower_32_bits(rq->hw_context->lrc_desc);
 	u32 ring_tail = intel_ring_set_tail(rq->ring, rq->tail) / sizeof(u64);
 
-	spin_lock(&client->wq_lock);
-
 	guc_wq_item_append(client, engine->guc_id, ctx_desc,
 			   ring_tail, rq->fence.seqno);
 	guc_ring_doorbell(client);
 
 	client->submissions[engine->id] += 1;
-
-	spin_unlock(&client->wq_lock);
 }
 
 /*
@@ -631,8 +631,9 @@ static void inject_preempt_context(struct work_struct *work)
 	data[6] = intel_guc_ggtt_offset(guc, guc->shared_data);
 
 	if (WARN_ON(intel_guc_send(guc, data, ARRAY_SIZE(data)))) {
-		execlists_clear_active(&engine->execlists,
-				       EXECLISTS_ACTIVE_PREEMPT);
+		intel_write_status_page(engine,
+					I915_GEM_HWS_PREEMPT,
+					GUC_PREEMPT_NONE);
 		tasklet_schedule(&engine->execlists.tasklet);
 	}
 
@@ -672,8 +673,6 @@ static void complete_preempt_context(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists *execlists = &engine->execlists;
 
-	GEM_BUG_ON(!execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT));
-
 	if (inject_preempt_hang(execlists))
 		return;
 
@@ -681,89 +680,90 @@ static void complete_preempt_context(struct intel_engine_cs *engine)
 	execlists_unwind_incomplete_requests(execlists);
 
 	wait_for_guc_preempt_report(engine);
-	intel_write_status_page(engine, I915_GEM_HWS_PREEMPT, 0);
+	intel_write_status_page(engine, I915_GEM_HWS_PREEMPT, GUC_PREEMPT_NONE);
 }
 
-/**
- * guc_submit() - Submit commands through GuC
- * @engine: engine associated with the commands
- *
- * The only error here arises if the doorbell hardware isn't functioning
- * as expected, which really shouln't happen.
- */
-static void guc_submit(struct intel_engine_cs *engine)
+static void guc_submit(struct intel_engine_cs *engine,
+		       struct i915_request **out,
+		       struct i915_request **end)
 {
 	struct intel_guc *guc = &engine->i915->guc;
-	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
-	unsigned int n;
+	struct intel_guc_client *client = guc->execbuf_client;
 
-	for (n = 0; n < execlists_num_ports(execlists); n++) {
-		struct i915_request *rq;
-		unsigned int count;
+	spin_lock(&client->wq_lock);
 
-		rq = port_unpack(&port[n], &count);
-		if (rq && count == 0) {
-			port_set(&port[n], port_pack(rq, ++count));
+	do {
+		struct i915_request *rq = *out++;
 
-			flush_ggtt_writes(rq->ring->vma);
+		flush_ggtt_writes(rq->ring->vma);
+		guc_add_request(guc, rq);
+	} while (out != end);
 
-			guc_add_request(guc, rq);
-		}
-	}
-}
-
-static void port_assign(struct execlist_port *port, struct i915_request *rq)
-{
-	GEM_BUG_ON(port_isset(port));
-
-	port_set(port, i915_request_get(rq));
+	spin_unlock(&client->wq_lock);
 }
 
 static inline int rq_prio(const struct i915_request *rq)
 {
-	return rq->sched.attr.priority;
+	return rq->sched.attr.priority | __NO_PREEMPTION;
 }
 
-static inline int port_prio(const struct execlist_port *port)
+static struct i915_request *schedule_in(struct i915_request *rq, int idx)
 {
-	return rq_prio(port_request(port)) | __NO_PREEMPTION;
+	trace_i915_request_in(rq, idx);
+
+	if (!rq->hw_context->inflight)
+		rq->hw_context->inflight = rq->engine;
+	intel_context_inflight_inc(rq->hw_context);
+
+	return i915_request_get(rq);
 }
 
-static bool __guc_dequeue(struct intel_engine_cs *engine)
+static void schedule_out(struct i915_request *rq)
+{
+	trace_i915_request_out(rq);
+
+	intel_context_inflight_dec(rq->hw_context);
+	if (!intel_context_inflight_count(rq->hw_context))
+		rq->hw_context->inflight = NULL;
+
+	i915_request_put(rq);
+}
+
+static void __guc_dequeue(struct intel_engine_cs *engine)
 {
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
-	struct i915_request *last = NULL;
-	const struct execlist_port * const last_port =
-		&execlists->port[execlists->port_mask];
+	struct i915_request **first = execlists->inflight;
+	struct i915_request ** const last_port = first + execlists->port_mask;
+	struct i915_request *last = first[0];
+	struct i915_request **port;
 	bool submit = false;
 	struct rb_node *rb;
 
 	lockdep_assert_held(&engine->active.lock);
 
-	if (port_isset(port)) {
+	if (last) {
 		if (intel_engine_has_preemption(engine)) {
 			struct guc_preempt_work *preempt_work =
 				&engine->i915->guc.preempt_work[engine->id];
 			int prio = execlists->queue_priority_hint;
 
-			if (i915_scheduler_need_preempt(prio,
-							port_prio(port))) {
-				execlists_set_active(execlists,
-						     EXECLISTS_ACTIVE_PREEMPT);
+			if (i915_scheduler_need_preempt(prio, rq_prio(last))) {
+				intel_write_status_page(engine,
+							I915_GEM_HWS_PREEMPT,
+							GUC_PREEMPT_INPROGRESS);
 				queue_work(engine->i915->guc.preempt_wq,
 					   &preempt_work->work);
-				return false;
+				return;
 			}
 		}
 
-		port++;
-		if (port_isset(port))
-			return false;
-	}
-	GEM_BUG_ON(port_isset(port));
+		if (*++first)
+			return;
 
+		last = NULL;
+	}
+
+	port = first;
 	while ((rb = rb_first_cached(&execlists->queue))) {
 		struct i915_priolist *p = to_priolist(rb);
 		struct i915_request *rq, *rn;
@@ -774,18 +774,15 @@ static bool __guc_dequeue(struct intel_engine_cs *engine)
 				if (port == last_port)
 					goto done;
 
-				if (submit)
-					port_assign(port, last);
+				*port = schedule_in(last,
+						    port - execlists->inflight);
 				port++;
 			}
 
 			list_del_init(&rq->sched.link);
-
 			__i915_request_submit(rq);
-			trace_i915_request_in(rq, port_index(port, execlists));
-
-			last = rq;
 			submit = true;
+			last = rq;
 		}
 
 		rb_erase_cached(&p->node, &execlists->queue);
@@ -794,58 +791,41 @@ static bool __guc_dequeue(struct intel_engine_cs *engine)
 done:
 	execlists->queue_priority_hint =
 		rb ? to_priolist(rb)->priority : INT_MIN;
-	if (submit)
-		port_assign(port, last);
-	if (last)
-		execlists_user_begin(execlists, execlists->port);
-
-	/* We must always keep the beast fed if we have work piled up */
-	GEM_BUG_ON(port_isset(execlists->port) &&
-		   !execlists_is_active(execlists, EXECLISTS_ACTIVE_USER));
-	GEM_BUG_ON(rb_first_cached(&execlists->queue) &&
-		   !port_isset(execlists->port));
-
-	return submit;
-}
-
-static void guc_dequeue(struct intel_engine_cs *engine)
-{
-	if (__guc_dequeue(engine))
-		guc_submit(engine);
+	if (submit) {
+		*port = schedule_in(last, port - execlists->inflight);
+		*++port = NULL;
+		guc_submit(engine, first, port);
+	}
+	execlists->active = execlists->inflight;
 }
 
 static void guc_submission_tasklet(unsigned long data)
 {
 	struct intel_engine_cs * const engine = (struct intel_engine_cs *)data;
 	struct intel_engine_execlists * const execlists = &engine->execlists;
-	struct execlist_port *port = execlists->port;
-	struct i915_request *rq;
+	struct i915_request **port, *rq;
 	unsigned long flags;
 
 	spin_lock_irqsave(&engine->active.lock, flags);
 
-	rq = port_request(port);
-	while (rq && i915_request_completed(rq)) {
-		trace_i915_request_out(rq);
-		i915_request_put(rq);
+	for (port = execlists->inflight; (rq = *port); port++) {
+		if (!i915_request_completed(rq))
+			break;
 
-		port = execlists_port_complete(execlists, port);
-		if (port_isset(port)) {
-			execlists_user_begin(execlists, port);
-			rq = port_request(port);
-		} else {
-			execlists_user_end(execlists);
-			rq = NULL;
-		}
+		schedule_out(rq);
+	}
+	if (port != execlists->inflight) {
+		int idx = port - execlists->inflight;
+		int rem = ARRAY_SIZE(execlists->inflight) - idx;
+		memmove(execlists->inflight, port, rem * sizeof(*port));
 	}
 
-	if (execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT) &&
-	    intel_read_status_page(engine, I915_GEM_HWS_PREEMPT) ==
+	if (intel_read_status_page(engine, I915_GEM_HWS_PREEMPT) ==
 	    GUC_PREEMPT_FINISHED)
 		complete_preempt_context(engine);
 
-	if (!execlists_is_active(execlists, EXECLISTS_ACTIVE_PREEMPT))
-		guc_dequeue(engine);
+	if (!intel_read_status_page(engine, I915_GEM_HWS_PREEMPT))
+		__guc_dequeue(engine);
 
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
@@ -959,7 +939,6 @@ static void guc_cancel_requests(struct intel_engine_cs *engine)
 
 	execlists->queue_priority_hint = INT_MIN;
 	execlists->queue = RB_ROOT_CACHED;
-	GEM_BUG_ON(port_isset(execlists->port));
 
 	spin_unlock_irqrestore(&engine->active.lock, flags);
 }
@@ -1422,7 +1401,7 @@ int intel_guc_submission_enable(struct intel_guc *guc)
 	 * and it is guaranteed that it will remove the work item from the
 	 * queue before our request is completed.
 	 */
-	BUILD_BUG_ON(ARRAY_SIZE(engine->execlists.port) *
+	BUILD_BUG_ON(ARRAY_SIZE(engine->execlists.inflight) *
 		     sizeof(struct guc_wq_item) *
 		     I915_NUM_ENGINES > GUC_WQ_SIZE);
 
diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
index 298bb7116c51..1a5b9e284ca9 100644
--- a/drivers/gpu/drm/i915/selftests/i915_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_request.c
@@ -366,13 +366,15 @@ static int __igt_breadcrumbs_smoketest(void *arg)
 
 		if (!wait_event_timeout(wait->wait,
 					i915_sw_fence_done(wait),
-					HZ / 2)) {
+					5 * HZ)) {
 			struct i915_request *rq = requests[count - 1];
 
-			pr_err("waiting for %d fences (last %llx:%lld) on %s timed out!\n",
-			       count,
+			pr_err("waiting for %d/%d fences (last %llx:%lld) on %s timed out!\n",
+			       atomic_read(&wait->pending), count,
 			       rq->fence.context, rq->fence.seqno,
 			       t->engine->name);
+			GEM_TRACE_DUMP();
+
 			i915_gem_set_wedged(t->engine->i915);
 			GEM_BUG_ON(!i915_request_completed(rq));
 			i915_sw_fence_wait(wait);