[igt-dev] [PATCH i-g-t 08/74] lib: Add an intel_ctx wrapper struct and helpers (v2)

[Jason Ekstrand <jason@jlekstrand.net>]

We're trying to clean up some of our technical debt in the i915 API.  In
particular, context mutability and unnecessary getparam().  There's
quite a bit of the introspection stuff that's not used by any userspace
other than IGT.  Most drivers don't care about fetching the set of
engines, for instance, because they don't forget about what set of
engines they asked for int the first place.

Unfortunately, IGT relies heavily on context introspection for just
about everything when it comes to multi-engine testing.  It also likes
to use ctx0 as temporary storage for whatever the current test config
is.  While effective at keeping IGC simple in some ways, this means
we're making heavy use of context mutability.  Also, passing data around
with in tests isn't really what contexts are for.

This patch adds a new intel_ctx_t struct which wraps a context and
remembers the full context configuration.  This will provide similar
ease-of-use without having use ctx0 as temporary storage.

v2 (Jason Ekstrand):
 - Make all intel_ctx_t's const
---
 lib/intel_ctx.c | 164 ++++++++++++++++++++++++++++++++++++++++++++++++
 lib/intel_ctx.h | 110 ++++++++++++++++++++++++++++++++
 lib/meson.build |   1 +
 3 files changed, 275 insertions(+)
 create mode 100644 lib/intel_ctx.c
 create mode 100644 lib/intel_ctx.h

diff --git a/lib/intel_ctx.c b/lib/intel_ctx.c
new file mode 100644
index 00000000..75c77fbd
--- /dev/null
+++ b/lib/intel_ctx.c
@@ -0,0 +1,164 @@
+/*
+ * Copyright © 2021 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 <stddef.h>
+
+#include "intel_ctx.h"
+#include "ioctl_wrappers.h"
+#include "i915/gem_engine_topology.h"
+
+static void
+add_user_ext(uint64_t *root_ext_u64, struct i915_user_extension *ext)
+{
+	ext->next_extension = *root_ext_u64;
+	*root_ext_u64 = to_user_pointer(ext);
+}
+
+static size_t sizeof_param_engines(int count)
+{
+	return offsetof(struct i915_context_param_engines, engines[count]);
+}
+
+#define SIZEOF_QUERY		offsetof(struct drm_i915_query_engine_info, \
+					 engines[GEM_MAX_ENGINES])
+
+intel_ctx_cfg_t intel_ctx_cfg_all_physical(int fd)
+{
+	uint8_t buff[SIZEOF_QUERY] = { };
+	struct drm_i915_query_engine_info *qei = (void *) buff;
+	intel_ctx_cfg_t cfg = {};
+	int i;
+
+	if (__gem_query_engines(fd, qei, SIZEOF_QUERY) == 0) {
+		cfg.num_engines = qei->num_engines;
+		for (i = 0; i < qei->num_engines; i++)
+			cfg.engines[i] = qei->engines[i].engine;
+	}
+
+	return cfg;
+}
+
+static int
+__context_create_cfg(int fd, const intel_ctx_cfg_t *cfg, uint32_t *ctx_id)
+{
+	uint64_t ext_root = 0;
+	I915_DEFINE_CONTEXT_PARAM_ENGINES(engines, GEM_MAX_ENGINES);
+	struct drm_i915_gem_context_create_ext_setparam engines_param, vm_param;
+	uint32_t i;
+
+	if (cfg->vm) {
+		vm_param = (struct drm_i915_gem_context_create_ext_setparam) {
+			.base = {
+				.name = I915_CONTEXT_CREATE_EXT_SETPARAM,
+			},
+			.param = {
+				.param = I915_CONTEXT_PARAM_VM,
+				.value = cfg->vm,
+			},
+		};
+		add_user_ext(&ext_root, &vm_param.base);
+	}
+
+	if (cfg->num_engines) {
+		memset(&engines, 0, sizeof(engines));
+		for (i = 0; i < cfg->num_engines; i++)
+			engines.engines[i] = cfg->engines[i];
+
+		engines_param = (struct drm_i915_gem_context_create_ext_setparam) {
+			.base = {
+				.name = I915_CONTEXT_CREATE_EXT_SETPARAM,
+			},
+			.param = {
+				.param = I915_CONTEXT_PARAM_ENGINES,
+				.size = sizeof_param_engines(cfg->num_engines),
+				.value = to_user_pointer(&engines),
+			},
+		};
+		add_user_ext(&ext_root, &engines_param.base);
+	}
+
+	return __gem_context_create_ext(fd, cfg->flags, ext_root, ctx_id);
+}
+
+int __intel_ctx_create(int fd, const intel_ctx_cfg_t *cfg,
+		       const intel_ctx_t **out_ctx)
+{
+	uint32_t ctx_id;
+	intel_ctx_t *ctx;
+	int err;
+
+	if (cfg)
+		err = __context_create_cfg(fd, cfg, &ctx_id);
+	else
+		err = __gem_context_create(fd, &ctx_id);
+	if (err)
+		return err;
+
+	ctx = calloc(1, sizeof(*ctx));
+	igt_assert(ctx);
+
+	ctx->id = ctx_id;
+	ctx->cfg = *cfg;
+
+	*out_ctx = ctx;
+	return 0;
+}
+
+const intel_ctx_t *intel_ctx_create(int fd, const intel_ctx_cfg_t *cfg)
+{
+	const intel_ctx_t *ctx;
+	int err;
+
+	err = __intel_ctx_create(fd, cfg, &ctx);
+	igt_assert_eq(err, 0);
+
+	return ctx;
+}
+
+static const intel_ctx_t __intel_ctx_0 = {};
+
+const intel_ctx_t *intel_ctx_0(int fd)
+{
+	(void)fd;
+	return &__intel_ctx_0;
+}
+
+const intel_ctx_t *intel_ctx_create_all_physical(int fd)
+{
+	intel_ctx_cfg_t cfg;
+
+	if (!gem_has_contexts(fd))
+		return intel_ctx_0(fd);
+
+	cfg = intel_ctx_cfg_all_physical(fd);
+	return intel_ctx_create(fd, &cfg);
+}
+
+void intel_ctx_destroy(int fd, const intel_ctx_t *ctx)
+{
+	if (!ctx || ctx->id == 0)
+		return;
+
+	gem_context_destroy(fd, ctx->id);
+	free((void *)ctx);
+}
diff --git a/lib/intel_ctx.h b/lib/intel_ctx.h
new file mode 100644
index 00000000..e61d6c91
--- /dev/null
+++ b/lib/intel_ctx.h
@@ -0,0 +1,110 @@
+/*
+ * Copyright © 2021 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 INTEL_CTX_H
+#define INTEL_CTX_H
+
+#include "igt_core.h"
+
+#include "i915_drm.h"
+
+#define GEM_MAX_ENGINES		I915_EXEC_RING_MASK + 1
+
+/**
+ * intel_ctx_cfg_t:
+ * @flags: Context create flags
+ * @vm: VM to inherit or 0 for using a per-context VM
+ * @num_engines: Number of client-specified engines or 0 for legacy mode
+ * @engines: Client-specified engines
+ *
+ * Represents the full configuration of an intel_ctx.
+ */
+typedef struct intel_ctx_cfg {
+	uint32_t flags;
+	uint32_t vm;
+	unsigned int num_engines;
+	struct i915_engine_class_instance engines[GEM_MAX_ENGINES];
+} intel_ctx_cfg_t;
+
+intel_ctx_cfg_t intel_ctx_cfg_all_physical(int fd);
+
+/**
+ * intel_ctx_t:
+ * @id: the context id/handle
+ * @cfg: the config used to create this context
+ *
+ * Represents the full configuration of an intel_ctx.
+ */
+typedef struct intel_ctx {
+	uint32_t id;
+	intel_ctx_cfg_t cfg;
+} intel_ctx_t;
+
+/**
+ * __intel_ctx_create:
+ * @fd: open i915 drm file descriptor
+ * @cfg: configuration for the created context
+ * @out_ctx: on success, the new intel_ctx_t pointer is written here
+ *
+ * Like intel_ctx_create but returns an error instead of asserting.
+ */
+int __intel_ctx_create(int fd, const intel_ctx_cfg_t *cfg,
+		       const intel_ctx_t **out_ctx);
+
+/**
+ * intel_ctx_create:
+ * @fd: open i915 drm file descriptor
+ * @cfg: configuration for the created context
+ *
+ * Creates a new intel_ctx_t with the given config
+ */
+const intel_ctx_t *intel_ctx_create(int i915, const intel_ctx_cfg_t *cfg);
+
+/**
+ * intel_ctx_0:
+ * @fd: open i915 drm file descriptor
+ *
+ * Returns an intel_ctx_t representing the default context.
+ */
+const intel_ctx_t *intel_ctx_0(int fd);
+
+/**
+ * intel_ctx_create_all_physical:
+ * @fd: open i915 drm file descriptor
+ *
+ * Creates an intel_ctx_t containing all physical engines.  On kernels
+ * without the engines API, the created context will be the same as
+ * intel_ctx_0() except that it will be a new GEM context.
+ */
+const intel_ctx_t *intel_ctx_create_all_physical(int fd);
+
+/**
+ * intel_ctx_destroy:
+ * @fd: open i915 drm file descriptor
+ * @ctx: context to destroy, or NULL
+ *
+ * Destroys an intel_ctx_t.
+ */
+void intel_ctx_destroy(int fd, const intel_ctx_t *ctx);
+
+#endif
diff --git a/lib/meson.build b/lib/meson.build
index 9929520e..d66748ad 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -42,6 +42,7 @@ lib_sources = [
 	'intel_batchbuffer.c',
 	'intel_bufops.c',
 	'intel_chipset.c',
+	'intel_ctx.c',
 	'intel_device_info.c',
 	'intel_os.c',
 	'intel_mmio.c',
-- 
2.31.1

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