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Commit 5d1808ec authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Assign every HW context a unique ID 



The hardware tracks contexts and expects all live contexts (those active
on the hardware) to have a unique identifier. This is used by the
hardware to assign pagefaults and the like to a particular context.

v2: Reorder to make sure ctx->link is not left dangling if the
assignment of a hw_id fails (Mika).

v3: We have 21bits of context space, not 20.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461833819-3991-17-git-send-email-chris@chris-wilson.co.uk
parent ef87bba8

drivers/gpu/drm/i915/i915_debugfs.c

+1 −1
Original line number Diff line number Diff line
@@ -2001,7 +2001,7 @@ static int i915_context_status(struct seq_file *m, void *unused) 
		    ctx->legacy_hw_ctx.rcs_state == NULL)

			continue;



		seq_puts(m, "HW context ");

		seq_printf(m, "HW context %u ", ctx->hw_id);

		describe_ctx(m, ctx);

		if (ctx == dev_priv->kernel_context)

			seq_printf(m, "(kernel context) ");

drivers/gpu/drm/i915/i915_drv.h

+10 −0
Original line number Diff line number Diff line
@@ -851,6 +851,9 @@ struct intel_context { 
	struct i915_ctx_hang_stats hang_stats;

	struct i915_hw_ppgtt *ppgtt;



	/* Unique identifier for this context, used by the hw for tracking */

	unsigned hw_id;



	/* Legacy ring buffer submission */

	struct {

		struct drm_i915_gem_object *rcs_state;
@@ -1838,6 +1841,13 @@ struct drm_i915_private { 
	DECLARE_HASHTABLE(mm_structs, 7);

	struct mutex mm_lock;



	/* The hw wants to have a stable context identifier for the lifetime

	 * of the context (for OA, PASID, faults, etc). This is limited

	 * in execlists to 21 bits.

	 */

	struct ida context_hw_ida;

#define MAX_CONTEXT_HW_ID (1<<21) /* exclusive */



	/* Kernel Modesetting */



	struct drm_crtc *plane_to_crtc_mapping[I915_MAX_PIPES];

drivers/gpu/drm/i915/i915_gem_context.c

+36 −0
Original line number Diff line number Diff line
@@ -171,6 +171,8 @@ void i915_gem_context_free(struct kref *ctx_ref) 
	if (ctx->legacy_hw_ctx.rcs_state)

		drm_gem_object_unreference(&ctx->legacy_hw_ctx.rcs_state->base);

	list_del(&ctx->link);



	ida_simple_remove(&ctx->i915->context_hw_ida, ctx->hw_id);

	kfree(ctx);

}
@@ -211,6 +213,28 @@ i915_gem_alloc_context_obj(struct drm_device *dev, size_t size) 
	return obj;

}



static int assign_hw_id(struct drm_i915_private *dev_priv, unsigned *out)

{

	int ret;



	ret = ida_simple_get(&dev_priv->context_hw_ida,

			     0, MAX_CONTEXT_HW_ID, GFP_KERNEL);

	if (ret < 0) {

		/* Contexts are only released when no longer active.

		 * Flush any pending retires to hopefully release some

		 * stale contexts and try again.

		 */

		i915_gem_retire_requests(dev_priv->dev);

		ret = ida_simple_get(&dev_priv->context_hw_ida,

				     0, MAX_CONTEXT_HW_ID, GFP_KERNEL);

		if (ret < 0)

			return ret;

	}



	*out = ret;

	return 0;

}



static struct intel_context *

__create_hw_context(struct drm_device *dev,

		    struct drm_i915_file_private *file_priv)
@@ -223,6 +247,12 @@ __create_hw_context(struct drm_device *dev, 
	if (ctx == NULL)

		return ERR_PTR(-ENOMEM);



	ret = assign_hw_id(dev_priv, &ctx->hw_id);

	if (ret) {

		kfree(ctx);

		return ERR_PTR(ret);

	}



	kref_init(&ctx->ref);

	list_add_tail(&ctx->link, &dev_priv->context_list);

	ctx->i915 = dev_priv;
@@ -366,6 +396,10 @@ int i915_gem_context_init(struct drm_device *dev) 
		}

	}



	/* Using the simple ida interface, the max is limited by sizeof(int) */

	BUILD_BUG_ON(MAX_CONTEXT_HW_ID > INT_MAX);

	ida_init(&dev_priv->context_hw_ida);



	if (i915.enable_execlists) {

		/* NB: intentionally left blank. We will allocate our own

		 * backing objects as we need them, thank you very much */
@@ -429,6 +463,8 @@ void i915_gem_context_fini(struct drm_device *dev) 


	i915_gem_context_unreference(dctx);

	dev_priv->kernel_context = NULL;



	ida_destroy(&dev_priv->context_hw_ida);

}



static int context_idr_cleanup(int id, void *p, void *data)