[Intel-gfx] [PATCH v9 08/10] drm/i915: Introduce execlist context status change notification

[Joonas Lahtinen]

On to, 2016-06-09 at 03:34 -0400, Zhi Wang wrote:
> This patch introduces an approach to track the execlist context status
> change.
> 
> GVT-g uses GVT context as the "shadow context". The content inside GVT
> context will be copied back to guest after the context is idle. And GVT-g
> has to know the status of the execlist context.
> 
> This function is configurable when creating a new GEM context. Currently,
> Only GVT-g will create the "status-change-notification" enabled GEM
> context.
> 
> v8:
> 
> - Remove the boolean flag in struct i915_gem_context. (Joonas)
> 
> v7:
> 
> - Remove per-engine ctx status notifiers. Use one status notifier for all
> engines. (Joonas)
> - Add prefix "INTEL_" for related definitions. (Joonas)
> - Refine the comments in execlists_context_status_change(). (Joonas)
> 
> v6:
> 
> - When !CONFIG_DRM_I915_GVT, make GVT code as dead code then compiler
> could automatically eliminate them for us. (Chris)
> - Always initialize the notifier header, so it could be switched on/off
> at runtime. (Chris)
> 
> v5:
> 
> - Only compile this feature when CONFIG_DRM_I915_GVT is enabled.(Tvrtko)
> 
> Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Signed-off-by: Zhi Wang <zhi.a.wang at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h         |  1 +
>  drivers/gpu/drm/i915/i915_gem_context.c |  1 +
>  drivers/gpu/drm/i915/intel_lrc.c        | 22 ++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_lrc.h        |  5 +++++
>  4 files changed, 29 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index a9e22200..c14eb56 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -880,6 +880,7 @@ struct i915_gem_context {
>  	} engine[I915_NUM_ENGINES];
>  	u32 ring_size;
>  	u32 desc_template;
> +	struct atomic_notifier_head status_notifier;
>  
>  	struct list_head link;
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index e636d85..3c1b83e 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -298,6 +298,7 @@ __create_hw_context(struct drm_device *dev,
>  	ctx->ring_size = 4 * PAGE_SIZE;
>  	ctx->desc_template = GEN8_CTX_ADDRESSING_MODE(dev_priv) <<
>  		GEN8_CTX_ADDRESSING_MODE_SHIFT;
> +	ATOMIC_INIT_NOTIFIER_HEAD(&ctx->status_notifier);
>  
>  	return ctx;
>  
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 2116f86..7f42b15 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -404,6 +404,20 @@ static void execlists_submit_requests(struct drm_i915_gem_request *rq0,
>  	spin_unlock_irq(&dev_priv->uncore.lock);
>  }
>  
> +static inline void execlists_context_status_change(
> +		struct drm_i915_gem_request *rq,
> +		unsigned long status)
> +{
> +	/*
> +	 * Only used when GVT-g is enabled now. When GVT-g is disabled,
> +	 * The compiler should eliminate this function as dead-code.
> +	 */
> +	if (!IS_ENABLED(CONFIG_DRM_I915_GVT))
> +		return;
> +
> +	atomic_notifier_call_chain(&rq->ctx->status_notifier, status, rq);
> +}
> +
>  static void execlists_context_unqueue(struct intel_engine_cs *engine)
>  {
>  	struct drm_i915_gem_request *req0 = NULL, *req1 = NULL;
> @@ -439,6 +453,12 @@ static void execlists_context_unqueue(struct intel_engine_cs *engine)
>  	if (unlikely(!req0))
>  		return;
>  
> +	execlists_context_status_change(req0, INTEL_CONTEXT_SCHEDULE_IN);
> +
> +	if (req1)
> +		execlists_context_status_change(req1,
> +				INTEL_CONTEXT_SCHEDULE_IN);

Indentation is incorrect here. Would it also fit on one line?

> +
>  	if (req0->elsp_submitted & engine->idle_lite_restore_wa) {
>  		/*
>  		 * WaIdleLiteRestore: make sure we never cause a lite restore
> @@ -477,6 +497,8 @@ execlists_check_remove_request(struct intel_engine_cs *engine, u32 ctx_id)
>  	if (--head_req->elsp_submitted > 0)
>  		return 0;
>  
> +	execlists_context_status_change(head_req, INTEL_CONTEXT_SCHEDULE_OUT);
> +
>  	list_del(&head_req->execlist_link);
>  	i915_gem_request_unreference(head_req);
>  
> diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
> index a8db42a..2b8255c 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/intel_lrc.h
> @@ -57,6 +57,11 @@
>  #define GEN8_CSB_READ_PTR(csb_status) \
>  	(((csb_status) & GEN8_CSB_READ_PTR_MASK) >> 8)
>  
> +enum {
> +	INTEL_CONTEXT_SCHEDULE_IN = 0,
> +	INTEL_CONTEXT_SCHEDULE_OUT,
> +};
> +
>  /* Logical Rings */
>  int intel_logical_ring_alloc_request_extras(struct drm_i915_gem_request *request);
>  int intel_logical_ring_reserve_space(struct drm_i915_gem_request *request);
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation