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        Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>,
        =?UTF-8?q?Andr=C3=A9=20Almeida?= <andrealmeid@igalia.com>
Subject: [RFC PATCH v3 2/4] drm: Create DRM_IOCTL_GET_RESET
Date:   Tue, 20 Jun 2023 21:57:17 -0300
Message-ID: <20230621005719.836857-3-andrealmeid@igalia.com>
In-Reply-To: <20230621005719.836857-1-andrealmeid@igalia.com>
References: <20230621005719.836857-1-andrealmeid@igalia.com>
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Create a new DRM ioctl operation to get the numbers of resets for a
given context. The numbers reflect just the resets that happened after
the context was created, and not since the machine was booted.

Create a debugfs interface to make easier to test the API without real
resets.

Signed-off-by: André Almeida <andrealmeid@igalia.com>
---
 drivers/gpu/drm/drm_debugfs.c |  2 ++
 drivers/gpu/drm/drm_ioctl.c   | 58 +++++++++++++++++++++++++++++++++++
 include/drm/drm_device.h      |  3 ++
 include/drm/drm_drv.h         |  3 ++
 include/uapi/drm/drm.h        | 21 +++++++++++++
 include/uapi/drm/drm_mode.h   | 15 +++++++++
 6 files changed, 102 insertions(+)

diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
index 4855230ba2c6..316dce60434d 100644
--- a/drivers/gpu/drm/drm_debugfs.c
+++ b/drivers/gpu/drm/drm_debugfs.c
@@ -251,6 +251,8 @@ int drm_debugfs_init(struct drm_minor *minor, int minor_id,
 		list_del(&entry->list);
 	}
 
+	debugfs_create_bool("drm_reset_spoof", 0644, minor->debugfs_root, &dev->reset_spoof);
+
 	return 0;
 }
 
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 7c9d66ee917d..23c282681ec7 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -528,6 +528,63 @@ int drm_version(struct drm_device *dev, void *data,
 	return err;
 }
 
+/**
+ * drm_spoof_reset - Spoof a fake reset
+ *
+ * @reset: reset struct to be spoofed
+ *
+ * Create a fake reset report for testing
+ */
+static void drm_spoof_reset(struct drm_get_reset *reset)
+{
+	reset->dev_reset_count = 1;
+	reset->ctx_reset_count = 0;
+	reset->flags = 0;
+	reset->ctx_id = 0;
+
+	DRM_INFO("[Spoofed] Reporting reset.ctx = %llu .dev = %llu\n",
+	       reset->ctx_reset_count, reset->dev_reset_count);
+}
+
+/**
+ * drm_getreset - Get reset information from a DRM device
+ *
+ * @dev DRM device
+ * @data user argument, pointing to a drm_get_reset structure
+ * @filp file pointer
+ *
+ * Return zero on success or negative number on failure.
+ *
+ * Fills in the reset information in data arg.
+ */
+int drm_getreset(struct drm_device *dev, void *data,
+			struct drm_file *file_priv)
+{
+	struct drm_get_reset *reset = data;
+	int ret = 0;
+
+	if (dev->reset_spoof) {
+		drm_spoof_reset(reset);
+		return 0;
+	}
+
+	if (!dev->driver->get_reset)
+		return -ENOSYS;
+
+	if (reset->flags)
+		return -EINVAL;
+
+	ret = dev->driver->get_reset(file_priv, dev, reset);
+
+	if (!ret)
+		DRM_INFO("Reporting reset.ctx = %llu .dev = %llu\n",
+		       reset->ctx_reset_count, reset->dev_reset_count);
+	else
+		DRM_WARN("%s failed with %d return\n", __func__, ret);
+
+	return ret;
+}
+
 static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv)
 {
 	/* ROOT_ONLY is only for CAP_SYS_ADMIN */
@@ -716,6 +773,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_LIST_LESSEES, drm_mode_list_lessees_ioctl, DRM_MASTER),
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_GET_LEASE, drm_mode_get_lease_ioctl, DRM_MASTER),
 	DRM_IOCTL_DEF(DRM_IOCTL_MODE_REVOKE_LEASE, drm_mode_revoke_lease_ioctl, DRM_MASTER),
+	DRM_IOCTL_DEF(DRM_IOCTL_GET_RESET, drm_getreset, DRM_RENDER_ALLOW),
 };
 
 #define DRM_CORE_IOCTL_COUNT	ARRAY_SIZE(drm_ioctls)
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index 7cf4afae2e79..fcd7b5d45cde 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -326,6 +326,9 @@ struct drm_device {
 	 */
 	struct list_head debugfs_list;
 
+	/* Spoof device reset for testing */
+	bool reset_spoof;
+
 	/* Everything below here is for legacy driver, never use! */
 	/* private: */
 #if IS_ENABLED(CONFIG_DRM_LEGACY)
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 89e2706cac56..518a9db157fb 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -401,6 +401,9 @@ struct drm_driver {
 			       struct drm_device *dev, uint32_t handle,
 			       uint64_t *offset);
 
+	int (*get_reset)(struct drm_file *file_priv,
+			 struct drm_device *dev, struct drm_get_reset *reset);
+
 	/**
 	 * @show_fdinfo:
 	 *
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index a87bbbbca2d4..a84559aa0d77 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -1169,6 +1169,27 @@ extern "C" {
  */
 #define DRM_IOCTL_MODE_GETFB2		DRM_IOWR(0xCE, struct drm_mode_fb_cmd2)
 
+/**
+ * DRM_IOCTL_GET_RESET - Get information about device resets
+ *
+ * This operation requests from the device information about resets. It should
+ * consider only resets that happens after the context is created, therefore,
+ * the counter should be zero during context creation.
+ *
+ * dev_reset_count tells how many resets have happened on this device, and
+ * ctx_reset_count tells how many of such resets were caused by this context.
+ *
+ * Flags can be used to tell if a reset is in progress, and userspace should
+ * wait until it's not in progress anymore to be able to create a new context;
+ * and to tell if the VRAM is considered lost. There's no safe way to clean this
+ * flag so if a context see this flag set, it should be like that until the end
+ * of the context.
+ */
+#define DRM_IOCTL_GET_RESET		DRM_IOWR(0xCF, struct drm_get_reset)
+
+#define DRM_RESET_IN_PROGRESS	0x1
+#define DRM_RESET_VRAM_LOST	0x2
+
 /*
  * Device specific ioctls should only be in their respective headers
  * The device specific ioctl range is from 0x40 to 0x9f.
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index 43691058d28f..c3257bd1af9c 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -1308,6 +1308,21 @@ struct drm_mode_rect {
 	__s32 y2;
 };
 
+/**
+ * struct drm_get_reset - Get information about a DRM device resets
+ * @ctx_id: the context id to be queried about resets
+ * @flags: flags
+ * @dev_reset_count: global counter of resets for a given DRM device
+ * @ctx_reset_count: of all the resets counted by this device, how many were
+ * caused by this context.
+ */
+struct drm_get_reset {
+	__u32 ctx_id;
+	__u32 flags;
+	__u64 dev_reset_count;
+	__u64 ctx_reset_count;
+};
+
 #if defined(__cplusplus)
 }
 #endif
-- 
2.41.0