Re: [PATCH v4 04/17] drm/i915/gt: Export the pinned context constructor and destructor

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, May 24, 2021 at 10:47:50PM -0700, Daniele Ceraolo Spurio wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Allow internal clients to create a pinned context.
> 
> v2 (Daniele): export destructor as well, allow optional usage of custom
> vm for maximum flexibility.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_engine.h    | 10 ++++++++
>  drivers/gpu/drm/i915/gt/intel_engine_cs.c | 29 +++++++++++++++--------
>  2 files changed, 29 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine.h b/drivers/gpu/drm/i915/gt/intel_engine.h
> index 47ee8578e511..a64d28aba257 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine.h
> +++ b/drivers/gpu/drm/i915/gt/intel_engine.h
> @@ -18,7 +18,9 @@
>  #include "intel_workarounds.h"
>  
>  struct drm_printer;
> +struct intel_context;
>  struct intel_gt;
> +struct lock_class_key;
>  
>  /* Early gen2 devices have a cacheline of just 32 bytes, using 64 is overkill,
>   * but keeps the logic simple. Indeed, the whole purpose of this macro is just
> @@ -255,6 +257,14 @@ struct i915_request *
>  intel_engine_find_active_request(struct intel_engine_cs *engine);
>  
>  u32 intel_engine_context_size(struct intel_gt *gt, u8 class);
> +struct intel_context *
> +intel_engine_create_pinned_context(struct intel_engine_cs *engine,
> +				   struct i915_address_space *vm,
> +				   unsigned int ring_size,
> +				   unsigned int hwsp,
> +				   struct lock_class_key *key,
> +				   const char *name);
> +void intel_engine_destroy_pinned_context(struct intel_context *ce);
>  
>  void intel_engine_init_active(struct intel_engine_cs *engine,
>  			      unsigned int subclass);
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index eba2da9679a5..8cbf11497e8e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -801,11 +801,13 @@ intel_engine_init_active(struct intel_engine_cs *engine, unsigned int subclass)
>  #endif
>  }
>  
> -static struct intel_context *
> -create_pinned_context(struct intel_engine_cs *engine,
> -		      unsigned int hwsp,
> -		      struct lock_class_key *key,
> -		      const char *name)
> +struct intel_context *
> +intel_engine_create_pinned_context(struct intel_engine_cs *engine,
> +				   struct i915_address_space *vm,
> +				   unsigned int ring_size,
> +				   unsigned int hwsp,
> +				   struct lock_class_key *key,
> +				   const char *name)
>  {
>  	struct intel_context *ce;
>  	int err;
> @@ -816,6 +818,12 @@ create_pinned_context(struct intel_engine_cs *engine,
>  
>  	__set_bit(CONTEXT_BARRIER_BIT, &ce->flags);
>  	ce->timeline = page_pack_bits(NULL, hwsp);
> +	ce->ring = __intel_context_ring_size(ring_size);

why do we need this now and we didn't need before?

> +
> +	if (vm) {
> +		i915_vm_put(ce->vm);
> +		ce->vm = i915_vm_get(vm);
> +	}

same question here...

>  
>  	err = intel_context_pin(ce); /* perma-pin so it is always available */
>  	if (err) {
> @@ -834,7 +842,7 @@ create_pinned_context(struct intel_engine_cs *engine,
>  	return ce;
>  }
>  
> -static void destroy_pinned_context(struct intel_context *ce)
> +void intel_engine_destroy_pinned_context(struct intel_context *ce)
>  {
>  	struct intel_engine_cs *engine = ce->engine;
>  	struct i915_vma *hwsp = engine->status_page.vma;
> @@ -854,8 +862,9 @@ create_kernel_context(struct intel_engine_cs *engine)
>  {
>  	static struct lock_class_key kernel;
>  
> -	return create_pinned_context(engine, I915_GEM_HWS_SEQNO_ADDR,
> -				     &kernel, "kernel_context");
> +	return intel_engine_create_pinned_context(engine, NULL, SZ_4K,
> +						  I915_GEM_HWS_SEQNO_ADDR,
> +						  &kernel, "kernel_context");
>  }
>  
>  /**
> @@ -898,7 +907,7 @@ static int engine_init_common(struct intel_engine_cs *engine)
>  	return 0;
>  
>  err_context:
> -	destroy_pinned_context(ce);
> +	intel_engine_destroy_pinned_context(ce);
>  	return ret;
>  }
>  
> @@ -956,7 +965,7 @@ void intel_engine_cleanup_common(struct intel_engine_cs *engine)
>  		fput(engine->default_state);
>  
>  	if (engine->kernel_context)
> -		destroy_pinned_context(engine->kernel_context);
> +		intel_engine_destroy_pinned_context(engine->kernel_context);
>  
>  	GEM_BUG_ON(!llist_empty(&engine->barrier_tasks));
>  	cleanup_status_page(engine);
> -- 
> 2.29.2
>