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

[Aravind Iddamsetty <aravind.iddamsetty@linux.intel.com>]

On 07-03-2025 19:54, Riana Tauro wrote:

Hi Riana,

I do think we can achieve the same functionality with module param and
we needn't reload the driver
if we are doing unbind, Since the driver will be loaded event after
unbind we can modify the module param
and once we bind the device back it can check if the BDF belongs to this
driver instance and configure the mode accordingly.

Thanks,
Aravind.
> 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@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
> + */
> +
> +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)
> +{
> +	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,
> +		},
> +	},
> +};
> +
> +int __init xe_configfs_init(void)
> +{
> +	int ret;
> +
> +	config_group_init(&xe_config_subsys.su_group);
> +	mutex_init(&xe_config_subsys.su_mutex);
> +	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;
>  };
>  
>  extern struct xe_modparam xe_modparam;