drm/i915: Provide a hook for selftests

Some pieces of code are independent of hardware but are very tricky to
exercise through the normal userspace ABI or via debugfs hooks. Being
able to create mock unit tests and execute them through CI is vital.
Start by adding a central point where we can execute unit tests and
a parameter to enable them. This is disabled by default as the
expectation is that these tests will occasionally explode.

To facilitate integration with igt, any parameter beginning with
i915.igt__ is interpreted as a subtest executable independently via
igt/drv_selftest.

Two classes of selftests are recognised: mock unit tests and integration
tests. Mock unit tests are run as soon as the module is loaded, before
the device is probed. At that point there is no driver instantiated and
all hw interactions must be "mocked". This is very useful for writing
universal tests to exercise code not typically run on a broad range of
architectures. Alternatively, you can hook into the live selftests and
run when the device has been instantiated - hw interactions are real.

v2: Add a macro for compiling conditional code for mock objects inside
real objects.
v3: Differentiate between mock unit tests and late integration test.
v4: List the tests in natural order, use igt to sort after modparam.
v5: s/late/live/
v6: s/unsigned long/unsigned int/
v7: Use igt_ prefixes for long helpers.
v8: Deobfuscate macros overriding functions, stop using -I$(src)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170213171558.20942-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/Kconfig.debug

@@ -26,6 +26,7 @@ config DRM_I915_DEBUG
         select DRM_DEBUG_MM if DRM=y
 	select DRM_DEBUG_MM_SELFTEST
 	select DRM_I915_SW_FENCE_DEBUG_OBJECTS
+	select DRM_I915_SELFTEST
         default n
         help
           Choose this option to turn on extra driver debugging that may affect
@@ -59,3 +60,18 @@ config DRM_I915_SW_FENCE_DEBUG_OBJECTS
           Recommended for driver developers only.
 
           If in doubt, say "N".
+
+config DRM_I915_SELFTEST
+	bool "Enable selftests upon driver load"
+	depends on DRM_I915
+	default n
+	select PRIME_NUMBERS
+	help
+	  Choose this option to allow the driver to perform selftests upon
+	  loading; also requires the i915.selftest=1 module parameter. To
+	  exit the module after running the selftests (i.e. to prevent normal
+	  module initialisation afterwards) use i915.selftest=-1.
+
+	  Recommended for driver developers only.
+
+	  If in doubt, say "N".

drivers/gpu/drm/i915/Makefile

@@ -117,6 +117,9 @@ i915-y += dvo_ch7017.o \
 
 # Post-mortem debug and GPU hang state capture
 i915-$(CONFIG_DRM_I915_CAPTURE_ERROR) += i915_gpu_error.o
+i915-$(CONFIG_DRM_I915_SELFTEST) += \
+	selftests/i915_random.o \
+	selftests/i915_selftest.o
 
 # virtual gpu code
 i915-y += i915_vgpu.o

drivers/gpu/drm/i915/i915_pci.c

@@ -27,6 +27,7 @@
 #include <linux/vga_switcheroo.h>
 
 #include "i915_drv.h"
+#include "i915_selftest.h"
 
 #define GEN_DEFAULT_PIPEOFFSETS \
 	.pipe_offsets = { PIPE_A_OFFSET, PIPE_B_OFFSET, \
@@ -473,10 +474,19 @@ static const struct pci_device_id pciidlist[] = {
 };
 MODULE_DEVICE_TABLE(pci, pciidlist);
 
+static void i915_pci_remove(struct pci_dev *pdev)
+{
+	struct drm_device *dev = pci_get_drvdata(pdev);
+
+	i915_driver_unload(dev);
+	drm_dev_unref(dev);
+}
+
 static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
 	struct intel_device_info *intel_info =
 		(struct intel_device_info *) ent->driver_data;
+	int err;
 
 	if (IS_ALPHA_SUPPORT(intel_info) && !i915.alpha_support) {
 		DRM_INFO("The driver support for your hardware in this kernel version is alpha quality\n"
@@ -500,15 +510,17 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (vga_switcheroo_client_probe_defer(pdev))
 		return -EPROBE_DEFER;
 
-	return i915_driver_load(pdev, ent);
-}
+	err = i915_driver_load(pdev, ent);
+	if (err)
+		return err;
 
-static void i915_pci_remove(struct pci_dev *pdev)
-{
-	struct drm_device *dev = pci_get_drvdata(pdev);
+	err = i915_live_selftests(pdev);
+	if (err) {
+		i915_pci_remove(pdev);
+		return err > 0 ? -ENOTTY : err;
+	}
 
-	i915_driver_unload(dev);
-	drm_dev_unref(dev);
+	return 0;
 }
 
 static struct pci_driver i915_pci_driver = {
@@ -522,6 +534,11 @@ static struct pci_driver i915_pci_driver = {
 static int __init i915_init(void)
 {
 	bool use_kms = true;
+	int err;
+
+	err = i915_mock_selftests();
+	if (err)
+		return err > 0 ? 0 : err;
 
 	/*
 	 * Enable KMS by default, unless explicitly overriden by

drivers/gpu/drm/i915/i915_selftest.h

@@ -0,0 +1,102 @@
+/*
+ * Copyright © 2016 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 __I915_SELFTEST_H__
+#define __I915_SELFTEST_H__
+
+struct pci_dev;
+struct drm_i915_private;
+
+struct i915_selftest {
+	unsigned long timeout_jiffies;
+	unsigned int timeout_ms;
+	unsigned int random_seed;
+	int mock;
+	int live;
+};
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+extern struct i915_selftest i915_selftest;
+
+int i915_mock_selftests(void);
+int i915_live_selftests(struct pci_dev *pdev);
+
+/* We extract the function declarations from i915_mock_selftests.h and
+ * i915_live_selftests.h Add your unit test declarations there!
+ *
+ * Mock unit tests are run very early upon module load, before the driver
+ * is probed. All hardware interactions, as well as other subsystems, must
+ * be "mocked".
+ *
+ * Live unit tests are run after the driver is loaded - all hardware
+ * interactions are real.
+ */
+#define selftest(name, func) int func(void);
+#include "selftests/i915_mock_selftests.h"
+#undef selftest
+#define selftest(name, func) int func(struct drm_i915_private *i915);
+#include "selftests/i915_live_selftests.h"
+#undef selftest
+
+struct i915_subtest {
+	int (*func)(void *data);
+	const char *name;
+};
+
+int __i915_subtests(const char *caller,
+		    const struct i915_subtest *st,
+		    unsigned int count,
+		    void *data);
+#define i915_subtests(T, data) \
+	__i915_subtests(__func__, T, ARRAY_SIZE(T), data)
+
+#define SUBTEST(x) { x, #x }
+
+#define I915_SELFTEST_DECLARE(x) x
+#define I915_SELFTEST_ONLY(x) unlikely(x)
+
+#else /* !IS_ENABLED(CONFIG_DRM_I915_SELFTEST) */
+
+static inline int i915_mock_selftests(void) { return 0; }
+static inline int i915_live_selftests(struct pci_dev *pdev) { return 0; }
+
+#define I915_SELFTEST_DECLARE(x)
+#define I915_SELFTEST_ONLY(x) 0
+
+#endif
+
+/* Using the i915_selftest_ prefix becomes a little unwieldy with the helpers.
+ * Instead we use the igt_ shorthand, in reference to the intel-gpu-tools
+ * suite of uabi test cases (which includes a test runner for our selftests).
+ */
+
+#define IGT_TIMEOUT(name__) \
+	unsigned long name__ = jiffies + i915_selftest.timeout_jiffies
+
+__printf(2, 3)
+bool __igt_timeout(unsigned long timeout, const char *fmt, ...);
+
+#define igt_timeout(t, fmt, ...) \
+	__igt_timeout((t), KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__)
+
+#endif /* !__I915_SELFTEST_H__ */

drivers/gpu/drm/i915/selftests/i915_live_selftests.h

@@ -0,0 +1,11 @@
+/* List each unit test as selftest(name, function)
+ *
+ * The name is used as both an enum and expanded as subtest__name to create
+ * a module parameter. It must be unique and legal for a C identifier.
+ *
+ * The function should be of type int function(void). It may be conditionally
+ * compiled using #if IS_ENABLED(DRM_I915_SELFTEST).
+ *
+ * Tests are executed in order by igt/drv_selftest
+ */
+selftest(sanitycheck, i915_live_sanitycheck) /* keep first (igt selfcheck) */

drivers/gpu/drm/i915/selftests/i915_mock_selftests.h

@@ -0,0 +1,11 @@
+/* List each unit test as selftest(name, function)
+ *
+ * The name is used as both an enum and expanded as subtest__name to create
+ * a module parameter. It must be unique and legal for a C identifier.
+ *
+ * The function should be of type int function(void). It may be conditionally
+ * compiled using #if IS_ENABLED(DRM_I915_SELFTEST).
+ *
+ * Tests are executed in order by igt/drv_selftest
+ */
+selftest(sanitycheck, i915_mock_sanitycheck) /* keep first (igt selfcheck) */

drivers/gpu/drm/i915/selftests/i915_random.c

@@ -0,0 +1,63 @@
+/*
+ * Copyright © 2016 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 <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "i915_random.h"
+
+static inline u32 i915_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state)
+{
+	return upper_32_bits((u64)prandom_u32_state(state) * ep_ro);
+}
+
+void i915_random_reorder(unsigned int *order, unsigned int count,
+			 struct rnd_state *state)
+{
+	unsigned int i, j;
+
+	for (i = 0; i < count; i++) {
+		BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32));
+		j = i915_prandom_u32_max_state(count, state);
+		swap(order[i], order[j]);
+	}
+}
+
+unsigned int *i915_random_order(unsigned int count, struct rnd_state *state)
+{
+	unsigned int *order, i;
+
+	order = kmalloc_array(count, sizeof(*order), GFP_TEMPORARY);
+	if (!order)
+		return order;
+
+	for (i = 0; i < count; i++)
+		order[i] = i;
+
+	i915_random_reorder(order, count, state);
+	return order;
+}

drivers/gpu/drm/i915/selftests/i915_random.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2016 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 __I915_SELFTESTS_RANDOM_H__
+#define __I915_SELFTESTS_RANDOM_H__
+
+#include <linux/random.h>
+
+#include "../i915_selftest.h"
+
+#define I915_RND_STATE_INITIALIZER(x) ({				\
+	struct rnd_state state__;					\
+	prandom_seed_state(&state__, (x));				\
+	state__;							\
+})
+
+#define I915_RND_STATE(name__) \
+	struct rnd_state name__ = I915_RND_STATE_INITIALIZER(i915_selftest.random_seed)
+
+#define I915_RND_SUBSTATE(name__, parent__) \
+	struct rnd_state name__ = I915_RND_STATE_INITIALIZER(prandom_u32_state(&(parent__)))
+
+unsigned int *i915_random_order(unsigned int count,
+				struct rnd_state *state);
+void i915_random_reorder(unsigned int *order,
+			 unsigned int count,
+			 struct rnd_state *state);
+
+#endif /* !__I915_SELFTESTS_RANDOM_H__ */