Re: [PATCH 7/9] drm/i915: Introduce execlist context status change notification

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

Hi,

On 17/05/16 09:19, 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. So GVT-g
> has to know the status of the execlist context.
>
> This function is configurable in the context creation service. Currently,
> Only GVT-g will create the "status-change-notification" enabled GEM
> context.
>
> v5:
>
> - Only compile this feature when CONFIG_DRM_I915_GVT is enabled.(Tvrtko)
>
> Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_drv.h  |  6 ++++++
>   drivers/gpu/drm/i915/intel_lrc.c | 30 ++++++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/intel_lrc.h |  7 +++++++
>   3 files changed, 43 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 91f69e5..9688006 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -882,9 +882,15 @@ struct intel_context {
>   		u64 lrc_desc;
>   		uint32_t *lrc_reg_state;
>   		bool initialised;
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +		struct atomic_notifier_head status_notifier_head;
> +#endif
>   	} engine[I915_NUM_ENGINES];
>   	u32 ring_buffer_size;
>   	bool use_48bit_addressing_mode;
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +	bool enable_status_change_notification;
> +#endif
>
>   	struct list_head link;
>   };
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index d97623f..9069836 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -415,6 +415,20 @@ static void execlists_submit_requests(struct drm_i915_gem_request *rq0,
>   	spin_unlock_irq(&dev_priv->uncore.lock);
>   }
>
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +static inline void execlists_context_status_change(
> +		struct drm_i915_gem_request *req,
> +		unsigned long status)
> +{
> +	if (!req->ctx->enable_status_change_notification)
> +		return;
> +
> +	atomic_notifier_call_chain(
> +			&req->ctx->engine[req->engine->id].status_notifier_head,
> +			status, req);
> +}

I recommend the usual:

#else
static inline void execlists_context_status_change(
		struct drm_i915_gem_request *req,
  		unsigned long status)
{
}

And then you don't have to have many #ifdefs scattered around.

> +#endif
> +
>   static void execlists_context_unqueue(struct intel_engine_cs *engine)
>   {
>   	struct drm_i915_gem_request *req0 = NULL, *req1 = NULL;
> @@ -450,6 +464,13 @@ static void execlists_context_unqueue(struct intel_engine_cs *engine)
>   	if (unlikely(!req0))
>   		return;
>
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +	execlists_context_status_change(req0, CONTEXT_SCHEDULE_IN);
> +
> +	if (req1)
> +		execlists_context_status_change(req1, CONTEXT_SCHEDULE_IN);
> +#endif
> +
>   	if (req0->elsp_submitted & engine->idle_lite_restore_wa) {
>   		/*
>   		 * WaIdleLiteRestore: make sure we never cause a lite restore
> @@ -488,6 +509,10 @@ execlists_check_remove_request(struct intel_engine_cs *engine, u32 ctx_id)
>   	if (--head_req->elsp_submitted > 0)
>   		return 0;
>
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +	execlists_context_status_change(head_req, CONTEXT_SCHEDULE_OUT);
> +#endif
> +
>   	list_del(&head_req->execlist_link);
>   	i915_gem_request_unreference(head_req);
>
> @@ -2534,6 +2559,11 @@ static int execlists_context_deferred_alloc(struct intel_context *ctx,
>   	ctx->engine[engine->id].state = ctx_obj;
>   	ctx->engine[engine->id].initialised = engine->init_context == NULL;
>
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +	if (ctx->enable_status_change_notification)
> +		ATOMIC_INIT_NOTIFIER_HEAD(
> +				&ctx->engine[engine->id].status_notifier_head);
> +#endif
>   	return 0;
>
>   error_ringbuf:
> diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h
> index 1afba03..99f84c9 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/intel_lrc.h
> @@ -57,6 +57,13 @@
>   #define GEN8_CSB_READ_PTR(csb_status) \
>   	(((csb_status) & GEN8_CSB_READ_PTR_MASK) >> 8)
>
> +#if IS_ENABLED(CONFIG_DRM_I915_GVT)
> +enum {
> +	CONTEXT_SCHEDULE_IN = 0,
> +	CONTEXT_SCHEDULE_OUT,
> +};
> +#endif
> +
>   /* 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);
>

Regards,

Tvrtko
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