Re: [igt-dev] [PATCH v12 5/7] lib/i915: add gem_engine_topology library

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

On 18/03/2019 23:28, Andi Shyti wrote:
> The gem_engine_topology library is a set of functions that
> interface with the query and getparam/setparam ioctls.
> 
> The library's access point is the 'intel_init_engine_list()'
> function that, everytime is called, generates the list of active
> engines and returns them in a 'struct intel_engine_data'. The
> structure contains only the engines that are actively present in
> the GPU.
> 
> The function can work in both the cases that the query and
> getparam ioctls are implemented or not by the running kernel. In
> case they are implemented, a query is made to the driver to fetch
> the list of active engines. In case they are not implemented, the
> list is taken from the 'intel_execution_engines2' array and
> stored only after checking their presence.
> 
> The library provides three helper functions:
> 
> 1. gem_topology_has_engine(): checks if the engine is present by
>     querying the driver in a way that the caller function wouldn't
>     know if the above ioctls are implemented.
> 
> 2. gem_set_eb_flags(): sets the execution buffer flag depending
>     whether it refers to context-engine mapping or not.
> 
> 3. gem_context_execbuf(): is a wrapper that executes the buffer
>     in a way that the calling function doesn't know about the
>     ioctls in the driver.
> 
> Signed-off-by: Andi Shyti <andi.shyti@intel.com>
> ---
>   lib/Makefile.sources           |   2 +
>   lib/i915/gem_engine_topology.c | 210 +++++++++++++++++++++++++++++++++
>   lib/i915/gem_engine_topology.h |  52 ++++++++
>   lib/meson.build                |   1 +
>   4 files changed, 265 insertions(+)
>   create mode 100644 lib/i915/gem_engine_topology.c
>   create mode 100644 lib/i915/gem_engine_topology.h
> 
> diff --git a/lib/Makefile.sources b/lib/Makefile.sources
> index cf2720981707..757bd7a17ebe 100644
> --- a/lib/Makefile.sources
> +++ b/lib/Makefile.sources
> @@ -13,6 +13,8 @@ lib_source_list =	 	\
>   	i915/gem_ring.c	\
>   	i915/gem_mman.c	\
>   	i915/gem_mman.h	\
> +	i915/gem_engine_topology.c	\
> +	i915/gem_engine_topology.h	\
>   	i915_3d.h		\
>   	i915_reg.h		\
>   	i915_pciids.h		\
> diff --git a/lib/i915/gem_engine_topology.c b/lib/i915/gem_engine_topology.c
> new file mode 100644
> index 000000000000..e836b3745e04
> --- /dev/null
> +++ b/lib/i915/gem_engine_topology.c
> @@ -0,0 +1,210 @@
> +/*
> + * Copyright © 2019 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include "drmtest.h"
> +#include "ioctl_wrappers.h"
> +
> +#include "i915/gem_engine_topology.h"
> +
> +#define SIZEOF_CTX_PARAM	offsetof(struct i915_context_param_engines, \
> +					class_instance[I915_EXEC_RING_MASK + 1])
> +#define SIZEOF_QUERY		offsetof(struct drm_i915_query_engine_info, \
> +					engines[I915_EXEC_RING_MASK + 1])
> +
> +static int __gem_query(int fd, struct drm_i915_query *q)
> +{
> +	int err = 0;
> +
> +	if (igt_ioctl(fd, DRM_IOCTL_I915_QUERY, q))
> +		err = -errno;
> +
> +	errno = 0;
> +	return err;
> +}
> +
> +static void gem_query(int fd, struct drm_i915_query *q)
> +{
> +	igt_assert_eq(__gem_query(fd, q), 0);
> +}
> +
> +static void query_engines(int fd,
> +			  struct drm_i915_query_engine_info *query_engines)
> +{
> +	struct drm_i915_query_item item = { };
> +	struct drm_i915_query query = { };
> +
> +	item.query_id = DRM_I915_QUERY_ENGINE_INFO;
> +	query.items_ptr = to_user_pointer(&item);
> +	query.num_items = 1;
> +	item.length = SIZEOF_QUERY;
> +
> +	item.data_ptr = to_user_pointer(query_engines);
> +
> +	gem_query(fd, &query);
> +}
> +
> +static void set_ctx_param_engines(struct intel_engine_data *ed)
> +{
> +	struct i915_context_param_engines *ctx_engine;
> +	struct drm_i915_gem_context_param ctx_param;
> +	uint8_t buff[SIZEOF_CTX_PARAM] = { };
> +	int i;
> +
> +	ctx_engine = (struct i915_context_param_engines *) buff;

Tiny detail - you could move assignment to declaration of you reorder them.

> +
> +	ctx_engine->extensions = 0;

No need since cleared when declared.

> +	for (i = 0; i < ed->nengines; i++) {
> +		ctx_engine->class_instance[i].engine_class =
> +							ed->engines[i].class;
> +		ctx_engine->class_instance[i].engine_instance =
> +							ed->engines[i].instance;

Could make the assignments more readable by having a pointer p = 
&ctx_engine->class_instance[0] and p++ in the for loop.

> +	}
> +
> +	ctx_param.size   = offsetof(typeof(*ctx_engine), class_instance[i + 1]);
> +	ctx_param.value  = to_user_pointer(ctx_engine);
> +	ctx_param.ctx_id = ed->ctx;
> +	ctx_param.param  = I915_CONTEXT_PARAM_ENGINES;
> +
> +	gem_context_set_param(ed->fd, &ctx_param);
> +}
> +
> +static void init_engine_list(struct intel_engine_data *ed)
> +{
> +	const char *class_names[] = { "rcs", "bcs", "vcs", "vecs" };
> +	struct drm_i915_query_engine_info *query_engine;
> +	unsigned char query_buffer[SIZEOF_QUERY] = { };

You used uint8_t above. I don't mind which one as long as it is consistent.

> +	int i;
> +
> +	query_engine = (struct drm_i915_query_engine_info *) query_buffer;

Could also assign in the declaration.

> +	query_engines(ed->fd, query_engine);
> +
> +	for (i = 0; i < query_engine->num_engines; i++) {
> +		char *name;
> +		__u16 class = query_engine->engines[i].engine_class;
> +		__u16 instance = query_engine->engines[i].engine_instance;
> +
> +		ed->engines[i].class = class;
> +		ed->engines[i].instance = instance;
> +
> +		/* if we don't recognise the class, then we mark it as "unk" */
> +		if (class >= ARRAY_SIZE(class_names))
> +			igt_assert(asprintf(&name, "unk-%d:%d",
> +					    class, instance) > 0);
> +		else
> +			igt_assert(asprintf(&name, "%s%d",
> +					    class_names[class], instance) > 0);

Names leak per iterator I think. Bummer, apart from using a big static 
table of all possible names, and borrowing those pointers here, I don't 
have any better ideas at the moment. Might actually be okay.

> +
> +		ed->engines[i].name = name;
> +	}
> +
> +	ed->nengines = query_engine->num_engines;
> +}
> +
> +struct intel_engine_data intel_init_engine_list(int fd, uint32_t ctx_id)
> +{
> +	struct drm_i915_gem_context_param ctx_param = {
> +		.param = I915_CONTEXT_PARAM_ENGINES,
> +		.ctx_id = ctx_id,
> +	};
> +	struct intel_engine_data engine_data = {
> +		.n = 0,

No need.

> +		.fd = fd,
> +		.ctx = ctx_id,
> +	};
> +
> +	if (__gem_context_get_param(fd, &ctx_param)) {
> +		const struct intel_execution_engine2 *e2;
> +
> +		igt_debug("using pre-allocated engine list\n");
> +
> +		__for_each_engine_class_instance(e2) {
> +			if (!gem_has_engine(fd, e2->class, e2->instance))
> +				continue;
> +
> +			engine_data.engines[engine_data.nengines].name =
> +								e2->name;
> +			engine_data.engines[engine_data.nengines].instance =
> +								e2->instance;
> +			engine_data.engines[engine_data.nengines].class =
> +								e2->class;

Also could keep a pointer to engine_data.engines[<current>] for more 
readable assignments.

> +			engine_data.nengines++;
> +		}
> +
> +		return engine_data;
> +	}
> +
> +	init_engine_list(&engine_data);

As far as I can see you missed the use case where we want to iterate 
over engines already defined in the context engine map.

So I think if the above __gem_context_get_param succeeds with non-zero 
size returned, you need to build engine_data based on those engines.

> +
> +	if (ctx_param.size == sizeof(struct i915_context_param_engines))
> +		set_ctx_param_engines(&engine_data);
> +

So this would change to something like:

if (ret == 0 && ctx_param.size == 0)
	init_engine_list(&engine_data);
	set_map = true;
else if (ret == 0)
	init_engine_list_from_ctx_engine_map(&engine_data, ctx_param);
else
	init_engine_list_from_static_tables(..);
	set_map = true;

if (set_map)
	set_ctx_param(...);

> +	return engine_data;
> +}
> +
> +bool gem_topology_has_engine(int fd, struct intel_execution_engine2 *e,
> +			     uint8_t i, uint32_t ctx)
> +{

Why do we need this helper?

> +	struct drm_i915_gem_context_param ctx_param = {
> +		.param = I915_CONTEXT_PARAM_ENGINES,
> +	};
> +
> +	if (!e)
> +		return false;
> +
> +	if (__gem_context_get_param(fd, &ctx_param))
> +		return gem_has_engine(fd, e->class, e->instance);
> +
> +	return gem_context_has_engine(fd, i, ctx);
> +}
> +
> +void gem_set_eb_flags(int fd, struct drm_i915_gem_execbuffer2 *eb,
> +		      struct intel_execution_engine2 e2,
> +		      uint8_t engine, uint32_t ctx)
> +{
> +	struct drm_i915_gem_context_param ctx_param = {
> +		.param = I915_CONTEXT_PARAM_ENGINES,
> +	};
> +
> +	if (__gem_context_get_param(fd, &ctx_param)) {
> +		eb->flags |= (I915_EXEC_RING_MASK & engine);
> +		eb->rsvd1 = ctx;
> +	} else {
> +		eb->flags |= gem_class_instance_to_eb_flags(fd, e2.class,
> +							    e2.instance);
> +	}
> +}

Store flags in struct intel_execution_engine2 while building the list 
and then just eb->flags |= e2->eb_flags in tests?

> +
> +int __gem_context_execbuf(int fd, struct drm_i915_gem_execbuffer2 *eb,
> +			  struct intel_execution_engine2 e2,
> +			  uint8_t engine, uint32_t ctx)
> +{
> +	gem_set_eb_flags(fd, eb, e2, engine, ctx);
> +	return __gem_execbuf(fd, eb);
> +}
> +
> +void gem_context_execbuf(int fd, struct drm_i915_gem_execbuffer2 *eb,
> +			 struct intel_execution_engine2 e2,
> +			 uint8_t index_map, uint32_t ctx)
> +{
> +	igt_assert_eq(__gem_context_execbuf(fd, eb, e2, index_map, ctx), 0);
> +}

Probably not want these two either.

> diff --git a/lib/i915/gem_engine_topology.h b/lib/i915/gem_engine_topology.h
> new file mode 100644
> index 000000000000..657b9397a181
> --- /dev/null
> +++ b/lib/i915/gem_engine_topology.h
> @@ -0,0 +1,52 @@
> +/*
> + * Copyright © 2019 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#ifndef GEM_ENGINE_TOPOLOGY_H
> +#define GEM_ENGINE_TOPOLOGY_H
> +
> +#include "igt_gt.h"
> +
> +struct intel_engine_data {
> +	int fd;
> +	uint32_t ctx;
> +
> +	uint32_t nengines;
> +	uint32_t n;

This is the current engine index? Could it come handy to also have a 
pointer to current engine in the iterator? Will see in later patches..

> +	struct intel_execution_engine2 engines[I915_EXEC_RING_MASK + 1];
> +};
> +
> +struct intel_engine_data intel_init_engine_list(int fd, uint32_t ctx_id);
> +bool gem_topology_has_engine(int fd, struct intel_execution_engine2 *e,
> +			     uint8_t i, uint32_t ctx);
> +
> +void gem_set_eb_flags(int fd, struct drm_i915_gem_execbuffer2 *eb,
> +		      struct intel_execution_engine2 e2,
> +		      uint8_t engine, uint32_t ctx);
> +int __gem_context_execbuf(int fd, struct drm_i915_gem_execbuffer2 *eb,
> +			  struct intel_execution_engine2 e2,
> +			  uint8_t engine, uint32_t ctx);
> +void gem_context_execbuf(int fd, struct drm_i915_gem_execbuffer2 *eb,
> +			 struct intel_execution_engine2 e2,
> +			 uint8_t index_map, uint32_t ctx);
> +
> +#endif /* GEM_ENGINE_TOPOLOGY_H */
> diff --git a/lib/meson.build b/lib/meson.build
> index 0eb5585d72b9..3cc52f97c8bf 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -5,6 +5,7 @@ lib_sources = [
>   	'i915/gem_submission.c',
>   	'i915/gem_ring.c',
>   	'i915/gem_mman.c',
> +	'i915/gem_engine_topology.c',
>   	'igt_color_encoding.c',
>   	'igt_debugfs.c',
>   	'igt_device.c',
> 

Regards,

Tvrtko
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