[PATCH 1/2] RFC drm/xe: Add configfs to enable survivability mode

[Lucas De Marchi]

On Fri, Mar 07, 2025 at 07:54:44PM +0530, Riana Tauro wrote:
>Registers a configfs subsystem called 'xe' to userspace. The user can
>use this to modify exposed attributes.
>
>Add survivability mode attribute (config/xe/survivability_mode) to the
>subsystem to allow the user to specify the card that should enter
>survivability mode.
>
>Signed-off-by: Riana Tauro <riana.tauro at intel.com>
>---
> drivers/gpu/drm/xe/Makefile      |  1 +
> drivers/gpu/drm/xe/xe_configfs.c | 95 ++++++++++++++++++++++++++++++++
> drivers/gpu/drm/xe/xe_configfs.h | 12 ++++
> drivers/gpu/drm/xe/xe_module.c   |  5 ++
> drivers/gpu/drm/xe/xe_module.h   |  1 +
> 5 files changed, 114 insertions(+)
> create mode 100644 drivers/gpu/drm/xe/xe_configfs.c
> create mode 100644 drivers/gpu/drm/xe/xe_configfs.h
>
>diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
>index 9699b08585f7..3f8c87292cee 100644
>--- a/drivers/gpu/drm/xe/Makefile
>+++ b/drivers/gpu/drm/xe/Makefile
>@@ -28,6 +28,7 @@ $(obj)/generated/%_wa_oob.c $(obj)/generated/%_wa_oob.h: $(obj)/xe_gen_wa_oob \
> xe-y += xe_bb.o \
> 	xe_bo.o \
> 	xe_bo_evict.o \
>+	xe_configfs.o \
> 	xe_devcoredump.o \
> 	xe_device.o \
> 	xe_device_sysfs.o \
>diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
>new file mode 100644
>index 000000000000..8c5f248e466d
>--- /dev/null
>+++ b/drivers/gpu/drm/xe/xe_configfs.c
>@@ -0,0 +1,95 @@
>+// SPDX-License-Identifier: MIT
>+/*
>+ * Copyright © 2025 Intel Corporation
>+ */
>+
>+#include <linux/configfs.h>
>+#include <linux/init.h>
>+#include <linux/module.h>
>+
>+#include "xe_configfs.h"
>+#include "xe_module.h"
>+
>+/**
>+ * DOC: Xe Configfs
>+ *
>+ * XE KMD registers a configfs subsystem called 'xe'to userspace that allows users to modify
>+ * the exposed attributes.
>+ *
>+ * Attributes:
>+ *
>+ * config/xe/survivability_mode : Write only attribute that allows user to specify the PCI address
>+ *				  of the card that has to enter survivability mode

I think the desired interface is actually that the user mkdir the bdf in
<configfs>/xe/. This populates the available config entries that the user
writes to.

>+ */
>+
>+void xe_configfs_clear_survivability_mode(void)
>+{
>+	kfree(xe_modparam.survivability_mode);
>+	xe_modparam.survivability_mode = NULL;
>+}
>+
>+static ssize_t survivability_mode_store(struct config_item *item, const char *page, size_t len)

once you handle the mkdir mentioned above, this should probably be
a boolean attr like this:

	drivers/nvme/target/configfs.c:CONFIGFS_ATTR(nvmet_, param_pi_enable);

>+{
>+	char *survivability_mode;
>+	int ret;
>+	unsigned int domain, bus, slot, function;
>+
>+	ret = sscanf(page, "%04x:%02x:%02x.%x", &domain, &bus, &slot, &function);
>+	if (ret != 4)
>+		return -EINVAL;
>+
>+	survivability_mode = kstrdup(page, GFP_KERNEL);
>+	if (!survivability_mode)
>+		return -ENOMEM;
>+
>+	xe_configfs_clear_survivability_mode();
>+	xe_modparam.survivability_mode = survivability_mode;
>+
>+	return len;
>+}
>+
>+CONFIGFS_ATTR_WO(, survivability_mode);
>+
>+static struct configfs_attribute *xe_configfs_attrs[] = {
>+	&attr_survivability_mode,
>+	NULL,
>+};
>+
>+static const struct config_item_type xe_config_type = {
>+	.ct_attrs	= xe_configfs_attrs,
>+	.ct_owner	= THIS_MODULE,
>+};
>+
>+static struct configfs_subsystem xe_config_subsys = {
>+	.su_group = {
>+		.cg_item = {
>+			.ci_namebuf = "xe",
>+			.ci_type = &xe_config_type,
>+		},
>+	},
>+};
>

so... it seems you are missing a configfs_group_operations.make_group.

>+int __init xe_configfs_init(void)
>+{
>+	int ret;
>+
>+	config_group_init(&xe_config_subsys.su_group);
>+	mutex_init(&xe_config_subsys.su_mutex);

this mutex_init seems odd, but inline with other drivers

>+	ret = configfs_register_subsystem(&xe_config_subsys);
>+	if (ret) {
>+		pr_err("Error %d while registering subsystem %s\n",
>+		       ret, xe_config_subsys.su_group.cg_item.ci_namebuf);
>+		mutex_destroy(&xe_config_subsys.su_mutex);
>+		return ret;
>+	}
>+
>+	return 0;
>+}
>+
>+void __exit xe_configfs_exit(void)
>+{
>+	xe_configfs_clear_survivability_mode();
>+	configfs_unregister_subsystem(&xe_config_subsys);
>+	mutex_destroy(&xe_config_subsys.su_mutex);
>+}
>+
>diff --git a/drivers/gpu/drm/xe/xe_configfs.h b/drivers/gpu/drm/xe/xe_configfs.h
>new file mode 100644
>index 000000000000..491629a2ca53
>--- /dev/null
>+++ b/drivers/gpu/drm/xe/xe_configfs.h
>@@ -0,0 +1,12 @@
>+/* SPDX-License-Identifier: MIT */
>+/*
>+ * Copyright © 2025 Intel Corporation
>+ */
>+#ifndef _XE_CONFIGFS_H_
>+#define _XE_CONFIGFS_H_
>+
>+int xe_configfs_init(void);
>+void xe_configfs_exit(void);
>+void xe_configfs_clear_survivability_mode(void);
>+
>+#endif
>diff --git a/drivers/gpu/drm/xe/xe_module.c b/drivers/gpu/drm/xe/xe_module.c
>index 475acdba2b55..15b3cf22193c 100644
>--- a/drivers/gpu/drm/xe/xe_module.c
>+++ b/drivers/gpu/drm/xe/xe_module.c
>@@ -11,6 +11,7 @@
> #include <drm/drm_module.h>
>
> #include "xe_drv.h"
>+#include "xe_configfs.h"
> #include "xe_hw_fence.h"
> #include "xe_pci.h"
> #include "xe_pm.h"
>@@ -91,6 +92,10 @@ static const struct init_funcs init_funcs[] = {
> 	{
> 		.init = xe_check_nomodeset,
> 	},
>+	{
>+		.init = xe_configfs_init,
>+		.exit = xe_configfs_exit,
>+	},
> 	{
> 		.init = xe_hw_fence_module_init,
> 		.exit = xe_hw_fence_module_exit,
>diff --git a/drivers/gpu/drm/xe/xe_module.h b/drivers/gpu/drm/xe/xe_module.h
>index 84339e509c80..c238dbee6bc7 100644
>--- a/drivers/gpu/drm/xe/xe_module.h
>+++ b/drivers/gpu/drm/xe/xe_module.h
>@@ -24,6 +24,7 @@ struct xe_modparam {
> #endif
> 	int wedged_mode;
> 	u32 svm_notifier_size;
>+	char *survivability_mode;

drop this.. We want a  config struct in the xe_device. It's actually
allocated by the mkdir in the configs and when we are probing, we should
find the config instace based on pdev and set the pointer xe->configfs
or something like that.

thanks
Lucas De Marchi

> };
>
> extern struct xe_modparam xe_modparam;
>-- 
>2.47.1
>