drm/i915/gvt: Pin the per-engine GVT shadow contexts

Our eventual goal is to rid request construction of struct_mutex, with
the short term step of lifting the struct_mutex requirements into the
higher levels (i.e. the caller must ensure that the context is already
pinned into the GTT). In this patch, we pin GVT's shadow context upon
allocation and so keep them pinned into the GGTT for as long as the
virtual machine is alive, and so we can use the simpler request
construction path safe in the knowledge that the hard work is already
done.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190426163336.15906-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gvt/gvt.h

@@ -149,9 +149,9 @@ struct intel_vgpu_submission_ops {
 struct intel_vgpu_submission {
 	struct intel_vgpu_execlist execlist[I915_NUM_ENGINES];
 	struct list_head workload_q_head[I915_NUM_ENGINES];
+	struct intel_context *shadow[I915_NUM_ENGINES];
 	struct kmem_cache *workloads;
 	atomic_t running_workload_num;
-	struct i915_gem_context *shadow_ctx;
 	union {
 		u64 i915_context_pml4;
 		u64 i915_context_pdps[GEN8_3LVL_PDPES];

drivers/gpu/drm/i915/gvt/kvmgt.c

@@ -1576,7 +1576,7 @@ hw_id_show(struct device *dev, struct device_attribute *attr,
 		struct intel_vgpu *vgpu = (struct intel_vgpu *)
 			mdev_get_drvdata(mdev);
 		return sprintf(buf, "%u\n",
-			       vgpu->submission.shadow_ctx->hw_id);
+			       vgpu->submission.shadow[0]->gem_context->hw_id);
 	}
 	return sprintf(buf, "\n");
 }

drivers/gpu/drm/i915/gvt/mmio_context.c

@@ -495,8 +495,7 @@ static void switch_mmio(struct intel_vgpu *pre,
 			 * itself.
 			 */
 			if (mmio->in_context &&
-			    !is_inhibit_context(intel_context_lookup(s->shadow_ctx,
-								     dev_priv->engine[ring_id])))
+			    !is_inhibit_context(s->shadow[ring_id]))
 				continue;
 
 			if (mmio->mask)

drivers/gpu/drm/i915/gvt/scheduler.c

@@ -36,6 +36,7 @@
 #include <linux/kthread.h>
 
 #include "i915_drv.h"
+#include "i915_gem_pm.h"
 #include "gvt.h"
 
 #define RING_CTX_OFF(x) \
@@ -277,18 +278,23 @@ static int shadow_context_status_change(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
-static void shadow_context_descriptor_update(struct intel_context *ce)
+static void
+shadow_context_descriptor_update(struct intel_context *ce,
+				 struct intel_vgpu_workload *workload)
 {
-	u64 desc = 0;
+	u64 desc = ce->lrc_desc;
 
-	desc = ce->lrc_desc;
-
-	/* Update bits 0-11 of the context descriptor which includes flags
+	/*
+	 * Update bits 0-11 of the context descriptor which includes flags
 	 * like GEN8_CTX_* cached in desc_template
 	 */
 	desc &= U64_MAX << 12;
 	desc |= ce->gem_context->desc_template & ((1ULL << 12) - 1);
 
+	desc &= ~(0x3 << GEN8_CTX_ADDRESSING_MODE_SHIFT);
+	desc |= workload->ctx_desc.addressing_mode <<
+		GEN8_CTX_ADDRESSING_MODE_SHIFT;
+
 	ce->lrc_desc = desc;
 }
 
@@ -365,26 +371,22 @@ intel_gvt_workload_req_alloc(struct intel_vgpu_workload *workload)
 {
 	struct intel_vgpu *vgpu = workload->vgpu;
 	struct intel_vgpu_submission *s = &vgpu->submission;
-	struct i915_gem_context *shadow_ctx = s->shadow_ctx;
 	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
-	struct intel_engine_cs *engine = dev_priv->engine[workload->ring_id];
 	struct i915_request *rq;
-	int ret = 0;
 
 	lockdep_assert_held(&dev_priv->drm.struct_mutex);
 
 	if (workload->req)
-		goto out;
+		return 0;
 
-	rq = i915_request_alloc(engine, shadow_ctx);
+	rq = i915_request_create(s->shadow[workload->ring_id]);
 	if (IS_ERR(rq)) {
 		gvt_vgpu_err("fail to allocate gem request\n");
-		ret = PTR_ERR(rq);
-		goto out;
+		return PTR_ERR(rq);
 	}
+
 	workload->req = i915_request_get(rq);
-out:
-	return ret;
+	return 0;
 }
 
 /**
@@ -399,10 +401,7 @@ int intel_gvt_scan_and_shadow_workload(struct intel_vgpu_workload *workload)
 {
 	struct intel_vgpu *vgpu = workload->vgpu;
 	struct intel_vgpu_submission *s = &vgpu->submission;
-	struct i915_gem_context *shadow_ctx = s->shadow_ctx;
 	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
-	struct intel_engine_cs *engine = dev_priv->engine[workload->ring_id];
-	struct intel_context *ce;
 	int ret;
 
 	lockdep_assert_held(&dev_priv->drm.struct_mutex);
@@ -410,29 +409,13 @@ int intel_gvt_scan_and_shadow_workload(struct intel_vgpu_workload *workload)
 	if (workload->shadow)
 		return 0;
 
-	/* pin shadow context by gvt even the shadow context will be pinned
-	 * when i915 alloc request. That is because gvt will update the guest
-	 * context from shadow context when workload is completed, and at that
-	 * moment, i915 may already unpined the shadow context to make the
-	 * shadow_ctx pages invalid. So gvt need to pin itself. After update
-	 * the guest context, gvt can unpin the shadow_ctx safely.
-	 */
-	ce = intel_context_pin(shadow_ctx, engine);
-	if (IS_ERR(ce)) {
-		gvt_vgpu_err("fail to pin shadow context\n");
-		return PTR_ERR(ce);
-	}
-
-	shadow_ctx->desc_template &= ~(0x3 << GEN8_CTX_ADDRESSING_MODE_SHIFT);
-	shadow_ctx->desc_template |= workload->ctx_desc.addressing_mode <<
-				    GEN8_CTX_ADDRESSING_MODE_SHIFT;
-
 	if (!test_and_set_bit(workload->ring_id, s->shadow_ctx_desc_updated))
-		shadow_context_descriptor_update(ce);
+		shadow_context_descriptor_update(s->shadow[workload->ring_id],
+						 workload);
 
 	ret = intel_gvt_scan_and_shadow_ringbuffer(workload);
 	if (ret)
-		goto err_unpin;
+		return ret;
 
 	if (workload->ring_id == RCS0 && workload->wa_ctx.indirect_ctx.size) {
 		ret = intel_gvt_scan_and_shadow_wa_ctx(&workload->wa_ctx);
@@ -444,8 +427,6 @@ int intel_gvt_scan_and_shadow_workload(struct intel_vgpu_workload *workload)
 	return 0;
 err_shadow:
 	release_shadow_wa_ctx(&workload->wa_ctx);
-err_unpin:
-	intel_context_unpin(ce);
 	return ret;
 }
 
@@ -672,7 +653,6 @@ static int dispatch_workload(struct intel_vgpu_workload *workload)
 	struct intel_vgpu *vgpu = workload->vgpu;
 	struct drm_i915_private *dev_priv = vgpu->gvt->dev_priv;
 	struct intel_vgpu_submission *s = &vgpu->submission;
-	struct i915_gem_context *shadow_ctx = s->shadow_ctx;
 	struct i915_request *rq;
 	int ring_id = workload->ring_id;
 	int ret;
@@ -683,7 +663,8 @@ static int dispatch_workload(struct intel_vgpu_workload *workload)
 	mutex_lock(&vgpu->vgpu_lock);
 	mutex_lock(&dev_priv->drm.struct_mutex);
 
-	ret = set_context_ppgtt_from_shadow(workload, shadow_ctx);
+	ret = set_context_ppgtt_from_shadow(workload,
+					    s->shadow[ring_id]->gem_context);
 	if (ret < 0) {
 		gvt_vgpu_err("workload shadow ppgtt isn't ready\n");
 		goto err_req;
@@ -911,11 +892,6 @@ static void complete_current_workload(struct intel_gvt *gvt, int ring_id)
 				intel_vgpu_trigger_virtual_event(vgpu, event);
 		}
 
-		/* unpin shadow ctx as the shadow_ctx update is done */
-		mutex_lock(&rq->i915->drm.struct_mutex);
-		intel_context_unpin(rq->hw_context);
-		mutex_unlock(&rq->i915->drm.struct_mutex);
-
 		i915_request_put(fetch_and_zero(&workload->req));
 	}
 
@@ -994,8 +970,6 @@ static int workload_thread(void *priv)
 				workload->ring_id, workload,
 				workload->vgpu->id);
 
-		intel_runtime_pm_get(gvt->dev_priv);
-
 		gvt_dbg_sched("ring id %d will dispatch workload %p\n",
 				workload->ring_id, workload);
 
@@ -1025,7 +999,6 @@ complete:
 			intel_uncore_forcewake_put(&gvt->dev_priv->uncore,
 					FORCEWAKE_ALL);
 
-		intel_runtime_pm_put_unchecked(gvt->dev_priv);
 		if (ret && (vgpu_is_vm_unhealthy(ret)))
 			enter_failsafe_mode(vgpu, GVT_FAILSAFE_GUEST_ERR);
 	}
@@ -1108,17 +1081,17 @@ err:
 }
 
 static void
-i915_context_ppgtt_root_restore(struct intel_vgpu_submission *s)
+i915_context_ppgtt_root_restore(struct intel_vgpu_submission *s,
+				struct i915_hw_ppgtt *ppgtt)
 {
-	struct i915_hw_ppgtt *i915_ppgtt = s->shadow_ctx->ppgtt;
 	int i;
 
-	if (i915_vm_is_4lvl(&i915_ppgtt->vm)) {
-		px_dma(&i915_ppgtt->pml4) = s->i915_context_pml4;
+	if (i915_vm_is_4lvl(&ppgtt->vm)) {
+		px_dma(&ppgtt->pml4) = s->i915_context_pml4;
 	} else {
 		for (i = 0; i < GEN8_3LVL_PDPES; i++)
-			px_dma(i915_ppgtt->pdp.page_directory[i]) =
-						s->i915_context_pdps[i];
+			px_dma(ppgtt->pdp.page_directory[i]) =
+				s->i915_context_pdps[i];
 	}
 }
 
@@ -1132,10 +1105,15 @@ i915_context_ppgtt_root_restore(struct intel_vgpu_submission *s)
 void intel_vgpu_clean_submission(struct intel_vgpu *vgpu)
 {
 	struct intel_vgpu_submission *s = &vgpu->submission;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
 
 	intel_vgpu_select_submission_ops(vgpu, ALL_ENGINES, 0);
-	i915_context_ppgtt_root_restore(s);
-	i915_gem_context_put(s->shadow_ctx);
+
+	i915_context_ppgtt_root_restore(s, s->shadow[0]->gem_context->ppgtt);
+	for_each_engine(engine, vgpu->gvt->dev_priv, id)
+		intel_context_unpin(s->shadow[id]);
+
 	kmem_cache_destroy(s->workloads);
 }
 
@@ -1161,17 +1139,17 @@ void intel_vgpu_reset_submission(struct intel_vgpu *vgpu,
 }
 
 static void
-i915_context_ppgtt_root_save(struct intel_vgpu_submission *s)
+i915_context_ppgtt_root_save(struct intel_vgpu_submission *s,
+			     struct i915_hw_ppgtt *ppgtt)
 {
-	struct i915_hw_ppgtt *i915_ppgtt = s->shadow_ctx->ppgtt;
 	int i;
 
-	if (i915_vm_is_4lvl(&i915_ppgtt->vm))
-		s->i915_context_pml4 = px_dma(&i915_ppgtt->pml4);
-	else {
+	if (i915_vm_is_4lvl(&ppgtt->vm)) {
+		s->i915_context_pml4 = px_dma(&ppgtt->pml4);
+	} else {
 		for (i = 0; i < GEN8_3LVL_PDPES; i++)
 			s->i915_context_pdps[i] =
-				px_dma(i915_ppgtt->pdp.page_directory[i]);
+				px_dma(ppgtt->pdp.page_directory[i]);
 	}
 }
 
@@ -1188,16 +1166,31 @@ i915_context_ppgtt_root_save(struct intel_vgpu_submission *s)
 int intel_vgpu_setup_submission(struct intel_vgpu *vgpu)
 {
 	struct intel_vgpu_submission *s = &vgpu->submission;
-	enum intel_engine_id i;
 	struct intel_engine_cs *engine;
+	struct i915_gem_context *ctx;
+	enum intel_engine_id i;
 	int ret;
 
-	s->shadow_ctx = i915_gem_context_create_gvt(
-			&vgpu->gvt->dev_priv->drm);
-	if (IS_ERR(s->shadow_ctx))
-		return PTR_ERR(s->shadow_ctx);
+	ctx = i915_gem_context_create_gvt(&vgpu->gvt->dev_priv->drm);
+	if (IS_ERR(ctx))
+		return PTR_ERR(ctx);
 
-	i915_context_ppgtt_root_save(s);
+	i915_context_ppgtt_root_save(s, ctx->ppgtt);
+
+	for_each_engine(engine, vgpu->gvt->dev_priv, i) {
+		struct intel_context *ce;
+
+		INIT_LIST_HEAD(&s->workload_q_head[i]);
+		s->shadow[i] = ERR_PTR(-EINVAL);
+
+		ce = intel_context_pin(ctx, engine);
+		if (IS_ERR(ce)) {
+			ret = PTR_ERR(ce);
+			goto out_shadow_ctx;
+		}
+
+		s->shadow[i] = ce;
+	}
 
 	bitmap_zero(s->shadow_ctx_desc_updated, I915_NUM_ENGINES);
 
@@ -1213,16 +1206,21 @@ int intel_vgpu_setup_submission(struct intel_vgpu *vgpu)
 		goto out_shadow_ctx;
 	}
 
-	for_each_engine(engine, vgpu->gvt->dev_priv, i)
-		INIT_LIST_HEAD(&s->workload_q_head[i]);
-
 	atomic_set(&s->running_workload_num, 0);
 	bitmap_zero(s->tlb_handle_pending, I915_NUM_ENGINES);
 
+	i915_gem_context_put(ctx);
 	return 0;
 
 out_shadow_ctx:
-	i915_gem_context_put(s->shadow_ctx);
+	i915_context_ppgtt_root_restore(s, ctx->ppgtt);
+	for_each_engine(engine, vgpu->gvt->dev_priv, i) {
+		if (IS_ERR(s->shadow[i]))
+			break;
+
+		intel_context_unpin(s->shadow[i]);
+	}
+	i915_gem_context_put(ctx);
 	return ret;
 }