[igt-dev] [PATCH i-g-t 08/12] lib/intel_ctx: Add xe context information

[Zbigniew Kempczyński]

Most complicated part in adopting i915_blt to intel_blt - which should
handle both drivers - is how to achieve pipelined execution. In term
pipelined execution I mean all gpu workloads are executed without
stalls.

Comparing to i915 relocations and softpinning xe architecture migrates
binding (this means also unbind operation) responsibility from the
kernel to user via vm_bind ioctl(). To avoid stalls user has to
provide in/out fences (syncobjs) between consecutive bindings/execs.
Of course for many igt tests we don't need pipelined execution,
just synchronous bind, then exec. But exercising the driver should
also cover pipelining to verify it is possible to work without stalls.

I decided to extend intel_ctx_t with all necessary for xe objects
(vm, engine, syncobjs) to get flexibility in deciding how to bind,
execute and wait for (synchronize) those operations. Context object
along with i915 engine is already passed to blitter library so adding
xe required fields doesn't break i915 but will allow xe path to get
all necessary data to execute.

Using intel_ctx with xe requires some code patterns caused by usage
of an allocator. For xe the allocator started tracking alloc()/free()
operations to do bind/unbind in one call just before execution.
I've added two helpers in intel_ctx which - intel_ctx_xe_exec()
and intel_ctx_xe_sync(). Depending how intel_ctx was created
(with 0 or real syncobj handles as in/bind/out fences) bind and exec
in intel_ctx_xe_exec() are pipelined but synchronize last operation
(exec). For real syncobjs they are used to join bind + exec calls
but there's no wait for exec (sync-out) completion. This allows
building more cascaded bind + exec operations without stalls.

To wait for a sync-out fence caller may use intel_ctx_xe_sync()
which is synchronous wait on syncobj. It allows user to reset
fences to prepare for next operation.

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
---
 lib/intel_ctx.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++-
 lib/intel_ctx.h |  14 ++++++
 2 files changed, 123 insertions(+), 1 deletion(-)

diff --git a/lib/intel_ctx.c b/lib/intel_ctx.c
index ded9c0f1e4..f210907fac 100644
--- a/lib/intel_ctx.c
+++ b/lib/intel_ctx.c
@@ -5,9 +5,12 @@
 
 #include <stddef.h>
 
+#include "i915/gem_engine_topology.h"
+#include "igt_syncobj.h"
+#include "intel_allocator.h"
 #include "intel_ctx.h"
 #include "ioctl_wrappers.h"
-#include "i915/gem_engine_topology.h"
+#include "xe/xe_ioctl.h"
 
 /**
  * SECTION:intel_ctx
@@ -390,3 +393,108 @@ unsigned int intel_ctx_engine_class(const intel_ctx_t *ctx, unsigned int engine)
 {
 	return intel_ctx_cfg_engine_class(&ctx->cfg, engine);
 }
+
+/**
+ * intel_ctx_xe:
+ * @fd: open i915 drm file descriptor
+ * @vm: vm
+ * @engine: engine
+ *
+ * Returns an intel_ctx_t representing the xe context.
+ */
+intel_ctx_t *intel_ctx_xe(int fd, uint32_t vm, uint32_t engine,
+			  uint32_t sync_in, uint32_t sync_bind, uint32_t sync_out)
+{
+	intel_ctx_t *ctx;
+
+	ctx = calloc(1, sizeof(*ctx));
+	igt_assert(ctx);
+
+	ctx->fd = fd;
+	ctx->vm = vm;
+	ctx->engine = engine;
+	ctx->sync_in = sync_in;
+	ctx->sync_bind = sync_bind;
+	ctx->sync_out = sync_out;
+
+	return ctx;
+}
+
+static int __xe_exec(int fd, struct drm_xe_exec *exec)
+{
+	int err = 0;
+
+	if (igt_ioctl(fd, DRM_IOCTL_XE_EXEC, exec)) {
+		err = -errno;
+		igt_assume(err != 0);
+	}
+	errno = 0;
+	return err;
+}
+
+int __intel_ctx_xe_exec(const intel_ctx_t *ctx, uint64_t ahnd, uint64_t bb_offset)
+{
+	struct drm_xe_sync syncs[2] = {
+		{ .flags = DRM_XE_SYNC_SYNCOBJ, },
+		{ .flags = DRM_XE_SYNC_SYNCOBJ | DRM_XE_SYNC_SIGNAL, },
+	};
+	struct drm_xe_exec exec = {
+		.engine_id = ctx->engine,
+		.syncs = (uintptr_t)syncs,
+		.num_syncs = 2,
+		.address = bb_offset,
+		.num_batch_buffer = 1,
+	};
+	uint32_t sync_in = ctx->sync_in;
+	uint32_t sync_bind = ctx->sync_bind ?: syncobj_create(ctx->fd, 0);
+	uint32_t sync_out = ctx->sync_out ?: syncobj_create(ctx->fd, 0);
+	int ret;
+
+	/* Synchronize allocator state -> vm */
+	intel_allocator_bind(ahnd, sync_in, sync_bind);
+
+	/* Pipelined exec */
+	syncs[0].handle = sync_bind;
+	syncs[1].handle = sync_out;
+
+	ret = __xe_exec(ctx->fd, &exec);
+	if (ret)
+		goto err;
+
+	if (!ctx->sync_bind || !ctx->sync_out)
+		syncobj_wait_err(ctx->fd, &sync_out, 1, INT64_MAX, 0);
+
+err:
+	if (!ctx->sync_bind)
+		syncobj_destroy(ctx->fd, sync_bind);
+
+	if (!ctx->sync_out)
+		syncobj_destroy(ctx->fd, sync_out);
+
+	return ret;
+}
+
+void intel_ctx_xe_exec(const intel_ctx_t *ctx, uint64_t ahnd, uint64_t bb_offset)
+{
+	igt_assert_eq(__intel_ctx_xe_exec(ctx, ahnd, bb_offset), 0);
+}
+
+#define RESET_SYNCOBJ(__fd, __sync) do { \
+	if (__sync) \
+		syncobj_reset((__fd), &(__sync), 1); \
+} while (0)
+
+int intel_ctx_xe_sync(intel_ctx_t *ctx, bool reset_syncs)
+{
+	int ret;
+
+	ret = syncobj_wait_err(ctx->fd, &ctx->sync_out, 1, INT64_MAX, 0);
+
+	if (reset_syncs) {
+		RESET_SYNCOBJ(ctx->fd, ctx->sync_in);
+		RESET_SYNCOBJ(ctx->fd, ctx->sync_bind);
+		RESET_SYNCOBJ(ctx->fd, ctx->sync_out);
+	}
+
+	return ret;
+}
diff --git a/lib/intel_ctx.h b/lib/intel_ctx.h
index 3cfeaae81e..59d0360ada 100644
--- a/lib/intel_ctx.h
+++ b/lib/intel_ctx.h
@@ -67,6 +67,14 @@ int intel_ctx_cfg_engine_class(const intel_ctx_cfg_t *cfg, unsigned int engine);
 typedef struct intel_ctx {
 	uint32_t id;
 	intel_ctx_cfg_t cfg;
+
+	/* Xe */
+	int fd;
+	uint32_t vm;
+	uint32_t engine;
+	uint32_t sync_in;
+	uint32_t sync_bind;
+	uint32_t sync_out;
 } intel_ctx_t;
 
 int __intel_ctx_create(int fd, const intel_ctx_cfg_t *cfg,
@@ -81,4 +89,10 @@ void intel_ctx_destroy(int fd, const intel_ctx_t *ctx);
 
 unsigned int intel_ctx_engine_class(const intel_ctx_t *ctx, unsigned int engine);
 
+intel_ctx_t *intel_ctx_xe(int fd, uint32_t vm, uint32_t engine,
+			  uint32_t sync_in, uint32_t sync_bind, uint32_t sync_out);
+int __intel_ctx_xe_exec(const intel_ctx_t *ctx, uint64_t ahnd, uint64_t bb_offset);
+void intel_ctx_xe_exec(const intel_ctx_t *ctx, uint64_t ahnd, uint64_t bb_offset);
+int intel_ctx_xe_sync(intel_ctx_t *ctx, bool reset_syncs);
+
 #endif
-- 
2.34.1