1 files changed, 411 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
new file mode 100644
index 000000000000..e9b46a2d0019
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_configfs.c
@@ -0,0 +1,411 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2025 Intel Corporation
+ */
+
+#include <linux/bitops.h>
+#include <linux/configfs.h>
+#include <linux/find.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/string.h>
+
+#include "xe_configfs.h"
+#include "xe_module.h"
+
+#include "xe_hw_engine_types.h"
+
+/**
+ * DOC: Xe Configfs
+ *
+ * Overview
+ * =========
+ *
+ * Configfs is a filesystem-based manager of kernel objects. XE KMD registers a
+ * configfs subsystem called ``'xe'`` that creates a directory in the mounted configfs directory
+ * The user can create devices under this directory and configure them as necessary
+ * See Documentation/filesystems/configfs.rst for more information about how configfs works.
+ *
+ * Create devices
+ * ===============
+ *
+ * In order to create a device, the user has to create a directory inside ``'xe'``::
+ *
+ *	mkdir /sys/kernel/config/xe/0000:03:00.0/
+ *
+ * Every device created is populated by the driver with entries that can be
+ * used to configure it::
+ *
+ *	/sys/kernel/config/xe/
+ *		.. 0000:03:00.0/
+ *			... survivability_mode
+ *
+ * Configure Attributes
+ * ====================
+ *
+ * Survivability mode:
+ * -------------------
+ *
+ * Enable survivability mode on supported cards. This setting only takes
+ * effect when probing the device. Example to enable it::
+ *
+ *	# echo 1 > /sys/kernel/config/xe/0000:03:00.0/survivability_mode
+ *	# echo 0000:03:00.0 > /sys/bus/pci/drivers/xe/bind  (Enters survivability mode if supported)
+ *
+ * Allowed engines:
+ * ----------------
+ *
+ * Allow only a set of engine(s) to be available, disabling the other engines
+ * even if they are available in hardware. This is applied after HW fuses are
+ * considered on each tile. Examples:
+ *
+ * Allow only one render and one copy engines, nothing else::
+ *
+ *	# echo 'rcs0,bcs0' > /sys/kernel/config/xe/0000:03:00.0/engines_allowed
+ *
+ * Allow only compute engines and first copy engine::
+ *
+ *	# echo 'ccs*,bcs0' > /sys/kernel/config/xe/0000:03:00.0/engines_allowed
+ *
+ * Note that the engine names are the per-GT hardware names. On multi-tile
+ * platforms, writing ``rcs0,bcs0`` to this file would allow the first render
+ * and copy engines on each tile.
+ *
+ * The requested configuration may not be supported by the platform and driver
+ * may fail to probe. For example: if at least one copy engine is expected to be
+ * available for migrations, but it's disabled. This is intended for debugging
+ * purposes only.
+ *
+ * Remove devices
+ * ==============
+ *
+ * The created device directories can be removed using ``rmdir``::
+ *
+ *	rmdir /sys/kernel/config/xe/0000:03:00.0/
+ */
+
+struct xe_config_device {
+	struct config_group group;
+
+	bool survivability_mode;
+	u64 engines_allowed;
+
+	/* protects attributes */
+	struct mutex lock;
+};
+
+struct engine_info {
+	const char *cls;
+	u64 mask;
+};
+
+/* Some helpful macros to aid on the sizing of buffer allocation when parsing */
+#define MAX_ENGINE_CLASS_CHARS 5
+#define MAX_ENGINE_INSTANCE_CHARS 2
+
+static const struct engine_info engine_info[] = {
+	{ .cls = "rcs", .mask = XE_HW_ENGINE_RCS_MASK },
+	{ .cls = "bcs", .mask = XE_HW_ENGINE_BCS_MASK },
+	{ .cls = "vcs", .mask = XE_HW_ENGINE_VCS_MASK },
+	{ .cls = "vecs", .mask = XE_HW_ENGINE_VECS_MASK },
+	{ .cls = "ccs", .mask = XE_HW_ENGINE_CCS_MASK },
+	{ .cls = "gsccs", .mask = XE_HW_ENGINE_GSCCS_MASK },
+};
+
+static struct xe_config_device *to_xe_config_device(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct xe_config_device, group);
+}
+
+static ssize_t survivability_mode_show(struct config_item *item, char *page)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+
+	return sprintf(page, "%d\n", dev->survivability_mode);
+}
+
+static ssize_t survivability_mode_store(struct config_item *item, const char *page, size_t len)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+	bool survivability_mode;
+	int ret;
+
+	ret = kstrtobool(page, &survivability_mode);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev->lock);
+	dev->survivability_mode = survivability_mode;
+	mutex_unlock(&dev->lock);
+
+	return len;
+}
+
+static ssize_t engines_allowed_show(struct config_item *item, char *page)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+	char *p = page;
+
+	for (size_t i = 0; i < ARRAY_SIZE(engine_info); i++) {
+		u64 mask = engine_info[i].mask;
+
+		if ((dev->engines_allowed & mask) == mask) {
+			p += sprintf(p, "%s*\n", engine_info[i].cls);
+		} else if (mask & dev->engines_allowed) {
+			u16 bit0 = __ffs64(mask), bit;
+
+			mask &= dev->engines_allowed;
+
+			for_each_set_bit(bit, (const unsigned long *)&mask, 64)
+				p += sprintf(p, "%s%u\n", engine_info[i].cls,
+					     bit - bit0);
+		}
+	}
+
+	return p - page;
+}
+
+static bool lookup_engine_mask(const char *pattern, u64 *mask)
+{
+	for (size_t i = 0; i < ARRAY_SIZE(engine_info); i++) {
+		u8 instance;
+		u16 bit;
+
+		if (!str_has_prefix(pattern, engine_info[i].cls))
+			continue;
+
+		pattern += strlen(engine_info[i].cls);
+
+		if (!strcmp(pattern, "*")) {
+			*mask = engine_info[i].mask;
+			return true;
+		}
+
+		if (kstrtou8(pattern, 10, &instance))
+			return false;
+
+		bit = __ffs64(engine_info[i].mask) + instance;
+		if (bit >= fls64(engine_info[i].mask))
+			return false;
+
+		*mask = BIT_ULL(bit);
+		return true;
+	}
+
+	return false;
+}
+
+static ssize_t engines_allowed_store(struct config_item *item, const char *page,
+				     size_t len)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+	size_t patternlen, p;
+	u64 mask, val = 0;
+
+	for (p = 0; p < len; p += patternlen + 1) {
+		char buf[MAX_ENGINE_CLASS_CHARS + MAX_ENGINE_INSTANCE_CHARS + 1];
+
+		patternlen = strcspn(page + p, ",\n");
+		if (patternlen >= sizeof(buf))
+			return -EINVAL;
+
+		memcpy(buf, page + p, patternlen);
+		buf[patternlen] = '\0';
+
+		if (!lookup_engine_mask(buf, &mask))
+			return -EINVAL;
+
+		val |= mask;
+	}
+
+	mutex_lock(&dev->lock);
+	dev->engines_allowed = val;
+	mutex_unlock(&dev->lock);
+
+	return len;
+}
+
+CONFIGFS_ATTR(, survivability_mode);
+CONFIGFS_ATTR(, engines_allowed);
+
+static struct configfs_attribute *xe_config_device_attrs[] = {
+	&attr_survivability_mode,
+	&attr_engines_allowed,
+	NULL,
+};
+
+static void xe_config_device_release(struct config_item *item)
+{
+	struct xe_config_device *dev = to_xe_config_device(item);
+
+	mutex_destroy(&dev->lock);
+	kfree(dev);
+}
+
+static struct configfs_item_operations xe_config_device_ops = {
+	.release	= xe_config_device_release,
+};
+
+static const struct config_item_type xe_config_device_type = {
+	.ct_item_ops	= &xe_config_device_ops,
+	.ct_attrs	= xe_config_device_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *xe_config_make_device_group(struct config_group *group,
+							const char *name)
+{
+	unsigned int domain, bus, slot, function;
+	struct xe_config_device *dev;
+	struct pci_dev *pdev;
+	int ret;
+
+	ret = sscanf(name, "%04x:%02x:%02x.%x", &domain, &bus, &slot, &function);
+	if (ret != 4)
+		return ERR_PTR(-EINVAL);
+
+	pdev = pci_get_domain_bus_and_slot(domain, bus, PCI_DEVFN(slot, function));
+	if (!pdev)
+		return ERR_PTR(-ENODEV);
+	pci_dev_put(pdev);
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	/* Default values */
+	dev->engines_allowed = U64_MAX;
+
+	config_group_init_type_name(&dev->group, name, &xe_config_device_type);
+
+	mutex_init(&dev->lock);
+
+	return &dev->group;
+}
+
+static struct configfs_group_operations xe_config_device_group_ops = {
+	.make_group	= xe_config_make_device_group,
+};
+
+static const struct config_item_type xe_configfs_type = {
+	.ct_group_ops	= &xe_config_device_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem xe_configfs = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "xe",
+			.ci_type = &xe_configfs_type,
+		},
+	},
+};
+
+static struct xe_config_device *configfs_find_group(struct pci_dev *pdev)
+{
+	struct config_item *item;
+	char name[64];
+
+	snprintf(name, sizeof(name), "%04x:%02x:%02x.%x", pci_domain_nr(pdev->bus),
+		 pdev->bus->number, PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
+
+	mutex_lock(&xe_configfs.su_mutex);
+	item = config_group_find_item(&xe_configfs.su_group, name);
+	mutex_unlock(&xe_configfs.su_mutex);
+
+	if (!item)
+		return NULL;
+
+	return to_xe_config_device(item);
+}
+
+/**
+ * xe_configfs_get_survivability_mode - get configfs survivability mode attribute
+ * @pdev: pci device
+ *
+ * find the configfs group that belongs to the pci device and return
+ * the survivability mode attribute
+ *
+ * Return: survivability mode if config group is found, false otherwise
+ */
+bool xe_configfs_get_survivability_mode(struct pci_dev *pdev)
+{
+	struct xe_config_device *dev = configfs_find_group(pdev);
+	bool mode;
+
+	if (!dev)
+		return false;
+
+	mode = dev->survivability_mode;
+	config_item_put(&dev->group.cg_item);
+
+	return mode;
+}
+
+/**
+ * xe_configfs_clear_survivability_mode - clear configfs survivability mode attribute
+ * @pdev: pci device
+ *
+ * find the configfs group that belongs to the pci device and clear survivability
+ * mode attribute
+ */
+void xe_configfs_clear_survivability_mode(struct pci_dev *pdev)
+{
+	struct xe_config_device *dev = configfs_find_group(pdev);
+
+	if (!dev)
+		return;
+
+	mutex_lock(&dev->lock);
+	dev->survivability_mode = 0;
+	mutex_unlock(&dev->lock);
+
+	config_item_put(&dev->group.cg_item);
+}
+
+/**
+ * xe_configfs_get_engines_allowed - get engine allowed mask from configfs
+ * @pdev: pci device
+ *
+ * Find the configfs group that belongs to the pci device and return
+ * the mask of engines allowed to be used.
+ *
+ * Return: engine mask with allowed engines
+ */
+u64 xe_configfs_get_engines_allowed(struct pci_dev *pdev)
+{
+	struct xe_config_device *dev = configfs_find_group(pdev);
+	u64 engines_allowed;
+
+	if (!dev)
+		return U64_MAX;
+
+	engines_allowed = dev->engines_allowed;
+	config_item_put(&dev->group.cg_item);
+
+	return engines_allowed;
+}
+
+int __init xe_configfs_init(void)
+{
+	struct config_group *root = &xe_configfs.su_group;
+	int ret;
+
+	config_group_init(root);
+	mutex_init(&xe_configfs.su_mutex);
+	ret = configfs_register_subsystem(&xe_configfs);
+	if (ret) {
+		pr_err("Error %d while registering %s subsystem\n",
+		       ret, root->cg_item.ci_namebuf);
+		return ret;
+	}
+
+	return 0;
+}
+
+void __exit xe_configfs_exit(void)
+{
+	configfs_unregister_subsystem(&xe_configfs);
+}
+