[PATCH i-g-t v11 3/6] lib/intel_multigpu: Introduce library for multi-GPU scenarios

[Kamil Konieczny]

From: Dominik Karol Piątkowski <dominik.karol.piatkowski at intel.com>

Implemented gem_require_multigpu in order to replace
igt_require(gpu_count > 1), as well as printing available
PCI devices if requirement fails.

Introduced gem_multigpu_count_class function that returns an actual
number of GPUs present in system, which allows for writing multi-GPU
test scenarios that does not require filter
--device pci:vendor=intel,device=discrete,card=all
to run as intended. Based on patch by Chris Wilson.

Introduced igt_multi_fork_foreach_gpu macro that helps with
writing multi-GPU test scenarios in idiomatic form:

igt_multi_fork_foreach_gpu(i915, DRIVER_INTEL)
	test_function(i915);
igt_waitchildren();

v10: squashed two commits which introduce multigpu functions (Zbigniew)
  renamed __id and id__ into __chipset/chipset__ (Zbigniew)
  used __drm_close_driver() instead of close() in first macro (Kamil)
v11: added functions descriptions (Janusz)

Cc: "Zbigniew Kempczyński" <zbigniew.kempczynski at intel.com>
Cc: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
Signed-off-by: "Dominik Karol Piątkowski" <dominik.karol.piatkowski at intel.com>
[Kamil: fixed whitespace and tabs, moved to lib/intel_multigpu.*]
Signed-off-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>
---
 lib/intel_multigpu.c | 62 ++++++++++++++++++++++++++++++++++++++++++++
 lib/intel_multigpu.h | 26 +++++++++++++++++++
 lib/meson.build      |  1 +
 3 files changed, 89 insertions(+)
 create mode 100644 lib/intel_multigpu.c
 create mode 100644 lib/intel_multigpu.h

diff --git a/lib/intel_multigpu.c b/lib/intel_multigpu.c
new file mode 100644
index 000000000..c4e7cf542
--- /dev/null
+++ b/lib/intel_multigpu.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#include "drmtest.h"
+#include "igt_core.h"
+#include "igt_device_scan.h"
+#include "intel_multigpu.h"
+
+/**
+ * gem_multigpu_count_class:
+ * @class: chipset, e.g. DRIVER_XE or DRIVER_INTEL
+ *
+ * Function counts number of GPU cards with the help of opening all of them.
+ *
+ * Returns: number of GPUs cards found
+ */
+int gem_multigpu_count_class(int class)
+{
+	int count = 0;
+
+	igt_foreach_gpu(fd, class)
+		count++;
+
+	return count;
+}
+
+static void print_gpus(int count, int gpu_num)
+{
+	struct igt_devices_print_format fmt = {
+		.type = IGT_PRINT_SIMPLE,
+		.option = IGT_PRINT_PCI,
+	};
+	int devices;
+
+	igt_info("PCI devices available in the system:\n");
+
+	igt_devices_scan(true);
+	devices = igt_device_filter_pci();
+	igt_devices_print(&fmt);
+
+	igt_info("Test requires at least %d GPUs, got %d, available %d\n", count, gpu_num, devices);
+}
+
+/**
+ * gem_require_multigpu:
+ * @count: minimum number of GPUs required found with filters
+ *
+ * Function checks number of filtered GPU cards.
+ * On error prints available GPUs found on PCI bus and skips.
+ */
+void gem_require_multigpu(int gpus_wanted)
+{
+	int gpu_filters = igt_device_filter_count();
+
+	if (gpu_filters >= gpus_wanted)
+		return;
+
+	print_gpus(gpus_wanted, gpu_filters);
+	igt_skip_on(gpu_filters < gpus_wanted);
+}
diff --git a/lib/intel_multigpu.h b/lib/intel_multigpu.h
new file mode 100644
index 000000000..5acfcd5f6
--- /dev/null
+++ b/lib/intel_multigpu.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#ifndef __INTEL_MULTIGPU_H
+#define __INTEL_MULTIGPU_H
+
+#include "drmtest.h"
+#include "igt_core.h"
+
+void gem_require_multigpu(int count);
+int gem_multigpu_count_class(int chipset);
+
+#define igt_foreach_gpu(fd__, chipset__) \
+	for (int igt_unique(i) = 0, fd__; \
+		(fd__ = __drm_open_driver_another(igt_unique(i)++, chipset__)) >= 0; \
+		__drm_close_driver(fd__))
+
+#define igt_multi_fork_foreach_gpu(__fd, __chipset) \
+	igt_multi_fork(igt_unique(__i), gem_multigpu_count_class(__chipset)) \
+		for (int __fd = drm_open_driver_another(igt_unique(__i), __chipset); \
+			__fd >= 0; \
+			drm_close_driver(__fd), __fd = -1) \
+
+#endif /* __INTEL_MULTIGPU_H */
diff --git a/lib/meson.build b/lib/meson.build
index 6122861d8..8251695e1 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -65,6 +65,7 @@ lib_sources = [
 	'intel_device_info.c',
 	'intel_mmio.c',
 	'intel_mocs.c',
+	'intel_multigpu.c',
 	'intel_pat.c',
 	'ioctl_wrappers.c',
 	'media_spin.c',
-- 
2.42.0