[PATCH 13/21] drm/i915/gem: Add an intermediate proto_context struct

[Jason Ekstrand <jason@jlekstrand.net>]

Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c   | 143 ++++++++++++++----
 .../gpu/drm/i915/gem/i915_gem_context_types.h |  21 +++
 .../gpu/drm/i915/gem/selftests/mock_context.c |  16 +-
 3 files changed, 150 insertions(+), 30 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index e5efd22c89ba2..3e883daab93bf 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -191,6 +191,95 @@ static int validate_priority(struct drm_i915_private *i915,
 	return 0;
 }
 
+static void proto_context_close(struct i915_gem_proto_context *pc)
+{
+	if (pc->vm)
+		i915_vm_put(pc->vm);
+	kfree(pc);
+}
+
+static int proto_context_set_persistence(struct drm_i915_private *i915,
+					 struct i915_gem_proto_context *pc,
+					 bool persist)
+{
+	if (test_bit(UCONTEXT_PERSISTENCE, &pc->user_flags) == persist)
+		return 0;
+
+	if (persist) {
+		/*
+		 * Only contexts that are short-lived [that will expire or be
+		 * reset] are allowed to survive past termination. We require
+		 * hangcheck to ensure that the persistent requests are healthy.
+		 */
+		if (!i915->params.enable_hangcheck)
+			return -EINVAL;
+
+		set_bit(UCONTEXT_PERSISTENCE, &pc->user_flags);
+	} else {
+		/* To cancel a context we use "preempt-to-idle" */
+		if (!(i915->caps.scheduler & I915_SCHEDULER_CAP_PREEMPTION))
+			return -ENODEV;
+
+		/*
+		 * If the cancel fails, we then need to reset, cleanly!
+		 *
+		 * If the per-engine reset fails, all hope is lost! We resort
+		 * to a full GPU reset in that unlikely case, but realistically
+		 * if the engine could not reset, the full reset does not fare
+		 * much better. The damage has been done.
+		 *
+		 * However, if we cannot reset an engine by itself, we cannot
+		 * cleanup a hanging persistent context without causing
+		 * colateral damage, and we should not pretend we can by
+		 * exposing the interface.
+		 */
+		if (!intel_has_reset_engine(&i915->gt))
+			return -ENODEV;
+
+		clear_bit(UCONTEXT_PERSISTENCE, &pc->user_flags);
+	}
+
+	return 0;
+}
+
+static struct i915_gem_proto_context *
+proto_context_create(struct drm_i915_private *i915, unsigned int flags)
+{
+	struct i915_gem_proto_context *pc;
+
+	if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE &&
+	    !HAS_EXECLISTS(i915))
+		return ERR_PTR(-EINVAL);
+
+	pc = kzalloc(sizeof(*pc), GFP_KERNEL);
+	if (!pc)
+		return ERR_PTR(-ENOMEM);
+
+	if (HAS_FULL_PPGTT(i915)) {
+		struct i915_ppgtt *ppgtt;
+
+		ppgtt = i915_ppgtt_create(&i915->gt);
+		if (IS_ERR(ppgtt)) {
+			drm_dbg(&i915->drm, "PPGTT setup failed (%ld)\n",
+				PTR_ERR(ppgtt));
+			proto_context_close(pc);
+			return ERR_CAST(ppgtt);
+		}
+		pc->vm = &ppgtt->vm;
+	}
+
+	pc->user_flags = 0;
+	set_bit(UCONTEXT_BANNABLE, &pc->user_flags);
+	set_bit(UCONTEXT_RECOVERABLE, &pc->user_flags);
+	proto_context_set_persistence(i915, pc, true);
+	pc->sched.priority = I915_PRIORITY_NORMAL;
+
+	if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE)
+		pc->single_timeline = true;
+
+	return pc;
+}
+
 static struct i915_address_space *
 context_get_vm_rcu(struct i915_gem_context *ctx)
 {
@@ -660,7 +749,8 @@ static int __context_set_persistence(struct i915_gem_context *ctx, bool state)
 }
 
 static struct i915_gem_context *
-__create_context(struct drm_i915_private *i915)
+__create_context(struct drm_i915_private *i915,
+		 const struct i915_gem_proto_context *pc)
 {
 	struct i915_gem_context *ctx;
 	struct i915_gem_engines *e;
@@ -673,7 +763,7 @@ __create_context(struct drm_i915_private *i915)
 
 	kref_init(&ctx->ref);
 	ctx->i915 = i915;
-	ctx->sched.priority = I915_PRIORITY_NORMAL;
+	ctx->sched = pc->sched;
 	mutex_init(&ctx->mutex);
 	INIT_LIST_HEAD(&ctx->link);
 
@@ -696,9 +786,7 @@ __create_context(struct drm_i915_private *i915)
 	 * is no remap info, it will be a NOP. */
 	ctx->remap_slice = ALL_L3_SLICES(i915);
 
-	i915_gem_context_set_bannable(ctx);
-	i915_gem_context_set_recoverable(ctx);
-	__context_set_persistence(ctx, true /* cgroup hook? */);
+	ctx->user_flags = pc->user_flags;
 
 	for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++)
 		ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
@@ -786,38 +874,23 @@ static void __assign_ppgtt(struct i915_gem_context *ctx,
 }
 
 static struct i915_gem_context *
-i915_gem_create_context(struct drm_i915_private *i915, unsigned int flags)
+i915_gem_create_context(struct drm_i915_private *i915,
+			const struct i915_gem_proto_context *pc)
 {
 	struct i915_gem_context *ctx;
 	int ret;
 
-	if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE &&
-	    !HAS_EXECLISTS(i915))
-		return ERR_PTR(-EINVAL);
-
-	ctx = __create_context(i915);
+	ctx = __create_context(i915, pc);
 	if (IS_ERR(ctx))
 		return ctx;
 
-	if (HAS_FULL_PPGTT(i915)) {
-		struct i915_ppgtt *ppgtt;
-
-		ppgtt = i915_ppgtt_create(&i915->gt);
-		if (IS_ERR(ppgtt)) {
-			drm_dbg(&i915->drm, "PPGTT setup failed (%ld)\n",
-				PTR_ERR(ppgtt));
-			context_close(ctx);
-			return ERR_CAST(ppgtt);
-		}
-
+	if (pc->vm) {
 		mutex_lock(&ctx->mutex);
-		__assign_ppgtt(ctx, &ppgtt->vm);
+		__assign_ppgtt(ctx, pc->vm);
 		mutex_unlock(&ctx->mutex);
-
-		i915_vm_put(&ppgtt->vm);
 	}
 
-	if (flags & I915_CONTEXT_CREATE_FLAGS_SINGLE_TIMELINE) {
+	if (pc->single_timeline) {
 		ret = drm_syncobj_create(&ctx->syncobj,
 					 DRM_SYNCOBJ_CREATE_SIGNALED,
 					 NULL);
@@ -883,6 +956,7 @@ int i915_gem_context_open(struct drm_i915_private *i915,
 			  struct drm_file *file)
 {
 	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct i915_gem_proto_context *pc;
 	struct i915_gem_context *ctx;
 	int err;
 	u32 id;
@@ -892,7 +966,14 @@ int i915_gem_context_open(struct drm_i915_private *i915,
 	/* 0 reserved for invalid/unassigned ppgtt */
 	xa_init_flags(&file_priv->vm_xa, XA_FLAGS_ALLOC1);
 
-	ctx = i915_gem_create_context(i915, 0);
+	pc = proto_context_create(i915, 0);
+	if (IS_ERR(pc)) {
+		err = PTR_ERR(pc);
+		goto err;
+	}
+
+	ctx = i915_gem_create_context(i915, pc);
+	proto_context_close(pc);
 	if (IS_ERR(ctx)) {
 		err = PTR_ERR(ctx);
 		goto err;
@@ -1884,6 +1965,7 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 {
 	struct drm_i915_private *i915 = to_i915(dev);
 	struct drm_i915_gem_context_create_ext *args = data;
+	struct i915_gem_proto_context *pc;
 	struct create_ext ext_data;
 	int ret;
 	u32 id;
@@ -1906,7 +1988,12 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 		return -EIO;
 	}
 
-	ext_data.ctx = i915_gem_create_context(i915, args->flags);
+	pc = proto_context_create(i915, args->flags);
+	if (IS_ERR(pc))
+		return PTR_ERR(pc);
+
+	ext_data.ctx = i915_gem_create_context(i915, pc);
+	proto_context_close(pc);
 	if (IS_ERR(ext_data.ctx))
 		return PTR_ERR(ext_data.ctx);
 
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
index df76767f0c41b..a42c429f94577 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
@@ -46,6 +46,27 @@ struct i915_gem_engines_iter {
 	const struct i915_gem_engines *engines;
 };
 
+/**
+ * struct i915_gem_proto_context - prototype context
+ *
+ * The struct i915_gem_proto_context represents the creation parameters for
+ * an i915_gem_context.  This is used to gather parameters provided either
+ * through creation flags or via SET_CONTEXT_PARAM so that, when we create
+ * the final i915_gem_context, those parameters can be immutable.
+ */
+struct i915_gem_proto_context {
+	/** @vm: See i915_gem_context::vm */
+	struct i915_address_space *vm;
+
+	/** @user_flags: See i915_gem_context::user_flags */
+	unsigned long user_flags;
+
+	/** @sched: See i915_gem_context::sched */
+	struct i915_sched_attr sched;
+
+	bool single_timeline;
+};
+
 /**
  * struct i915_gem_context - client state
  *
diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
index 51b5a3421b400..e0f512ef7f3c6 100644
--- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
@@ -80,11 +80,17 @@ void mock_init_contexts(struct drm_i915_private *i915)
 struct i915_gem_context *
 live_context(struct drm_i915_private *i915, struct file *file)
 {
+	struct i915_gem_proto_context *pc;
 	struct i915_gem_context *ctx;
 	int err;
 	u32 id;
 
-	ctx = i915_gem_create_context(i915, 0);
+	pc = proto_context_create(i915, 0);
+	if (IS_ERR(pc))
+		return ERR_CAST(pc);
+
+	ctx = i915_gem_create_context(i915, pc);
+	proto_context_close(pc);
 	if (IS_ERR(ctx))
 		return ctx;
 
@@ -142,8 +148,14 @@ struct i915_gem_context *
 kernel_context(struct drm_i915_private *i915)
 {
 	struct i915_gem_context *ctx;
+	struct i915_gem_proto_context *pc;
+
+	pc = proto_context_create(i915, 0);
+	if (IS_ERR(pc))
+		return ERR_CAST(pc);
 
-	ctx = i915_gem_create_context(i915, 0);
+	ctx = i915_gem_create_context(i915, pc);
+	proto_context_close(pc);
 	if (IS_ERR(ctx))
 		return ctx;
 
-- 
2.31.1

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