Re: [PATCH v10 1/4] drm/xe: Validate wedged_mode parameter and define enum for modes

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Nov 25, 2025 at 02:54:19PM +0100, Lukasz Laguna wrote:
> Check correctness of the wedged_mode parameter input to ensure only
> supported values are accepted. Additionally, replace magic numbers with
> a clearly defined enum.
> 
> Signed-off-by: Lukasz Laguna <lukasz.laguna@intel.com>
> ---
> v10:
>  - define enum outside of the xe_device struct,
>  - fix description of module parameter (Michal).
> ---
>  drivers/gpu/drm/xe/xe_debugfs.c      |  5 +--
>  drivers/gpu/drm/xe/xe_device.c       | 46 ++++++++++++++++++++++++++--
>  drivers/gpu/drm/xe/xe_device.h       |  2 ++
>  drivers/gpu/drm/xe/xe_device_types.h | 19 +++++++++++-
>  drivers/gpu/drm/xe/xe_guc_ads.c      |  4 +--
>  drivers/gpu/drm/xe/xe_guc_capture.c  |  9 +++++-
>  drivers/gpu/drm/xe/xe_guc_submit.c   |  7 +++--
>  drivers/gpu/drm/xe/xe_module.c       | 10 +++---
>  drivers/gpu/drm/xe/xe_module.h       |  2 +-
>  9 files changed, 88 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
> index 1d5a2a43a9d7..e7cdfb1cda8c 100644
> --- a/drivers/gpu/drm/xe/xe_debugfs.c
> +++ b/drivers/gpu/drm/xe/xe_debugfs.c
> @@ -265,8 +265,9 @@ static ssize_t wedged_mode_set(struct file *f, const char __user *ubuf,
>  	if (ret)
>  		return ret;
>  
> -	if (wedged_mode > 2)
> -		return -EINVAL;
> +	ret = xe_device_validate_wedged_mode(xe, wedged_mode);
> +	if (ret)
> +		return ret;
>  
>  	if (xe->wedged.mode == wedged_mode)
>  		return size;
> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c

Please, while at it, please update its doc block:

 * DOC: Xe Device Wedging

> index 1197f914ef77..f6216c4f83f9 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -760,7 +760,10 @@ int xe_device_probe_early(struct xe_device *xe)
>  	if (err)
>  		return err;
>  
> -	xe->wedged.mode = xe_modparam.wedged_mode;
> +	xe->wedged.mode = xe_device_validate_wedged_mode(xe, xe_modparam.wedged_mode) ?
> +			  XE_WEDGED_MODE_DEFAULT : xe_modparam.wedged_mode;
> +	drm_dbg(&xe->drm, "wedged_mode: setting mode (%u) %s\n",
> +		xe->wedged.mode, xe_wedged_mode_to_string(xe->wedged.mode));
>  
>  	err = xe_device_vram_alloc(xe);
>  	if (err)
> @@ -1250,7 +1253,7 @@ void xe_device_declare_wedged(struct xe_device *xe)
>  	struct xe_gt *gt;
>  	u8 id;
>  
> -	if (xe->wedged.mode == 0) {
> +	if (xe->wedged.mode == XE_WEDGED_MODE_NEVER) {
>  		drm_dbg(&xe->drm, "Wedged mode is forcibly disabled\n");
>  		return;
>  	}
> @@ -1284,3 +1287,42 @@ void xe_device_declare_wedged(struct xe_device *xe)
>  		drm_dev_wedged_event(&xe->drm, xe->wedged.method, NULL);
>  	}
>  }
> +
> +/**
> + * xe_device_validate_wedged_mode - Check if given mode is supported
> + * @xe: the &xe_device
> + * @mode: requested mode to validate
> + *
> + * Check whether the provided wedged mode is supported.
> + *
> + * Return: 0 if mode is supported, error code otherwise.
> + */
> +int xe_device_validate_wedged_mode(struct xe_device *xe, unsigned int mode)
> +{
> +	if (mode > XE_WEDGED_MODE_UPON_ANY_HANG) {
> +		drm_dbg(&xe->drm, "wedged_mode: invalid value (%u)\n", mode);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * xe_wedged_mode_to_string - Convert enum value to string.
> + * @mode: the &xe_wedged_mode to convert
> + *
> + * Returns: wedged mode as a user friendly string.
> + */
> +const char *xe_wedged_mode_to_string(enum xe_wedged_mode mode)
> +{
> +	switch (mode) {
> +	case XE_WEDGED_MODE_NEVER:
> +		return "never";
> +	case XE_WEDGED_MODE_UPON_CRITICAL_ERROR:
> +		return "upon-critical-error";
> +	case XE_WEDGED_MODE_UPON_ANY_HANG:
> +		return "upon-any-hang";
> +	default:
> +		return "<invalid>";
> +	}
> +}
> diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
> index 32cc6323b7f6..2fffa88f91b0 100644
> --- a/drivers/gpu/drm/xe/xe_device.h
> +++ b/drivers/gpu/drm/xe/xe_device.h
> @@ -189,6 +189,8 @@ static inline bool xe_device_wedged(struct xe_device *xe)
>  
>  void xe_device_set_wedged_method(struct xe_device *xe, unsigned long method);
>  void xe_device_declare_wedged(struct xe_device *xe);
> +int xe_device_validate_wedged_mode(struct xe_device *xe, unsigned int mode);
> +const char *xe_wedged_mode_to_string(enum xe_wedged_mode mode);
>  
>  struct xe_file *xe_file_get(struct xe_file *xef);
>  void xe_file_put(struct xe_file *xef);
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 6ce3247d1bd8..81bf4a70b888 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -43,6 +43,23 @@ struct xe_pat_ops;
>  struct xe_pxp;
>  struct xe_vram_region;
>  
> +/**
> + * enum xe_wedged_mode - possible wedged modes
> + * @XE_WEDGED_MODE_NEVER: Device will never be declared wedged.
> + * @XE_WEDGED_MODE_UPON_CRITICAL_ERROR: Device will be declared wedged only in
> + *	case of critical errors. This is the default mode.
> + * @XE_WEDGED_MODE_UPON_ANY_HANG: Device will be declared wedged on any hang.
> + *	In this mode, engine resets are disabled.
> + */
> +enum xe_wedged_mode {
> +	XE_WEDGED_MODE_NEVER = 0,
> +	XE_WEDGED_MODE_UPON_CRITICAL_ERROR = 1,
> +	XE_WEDGED_MODE_UPON_ANY_HANG = 2,
> +};
> +
> +#define XE_WEDGED_MODE_DEFAULT		XE_WEDGED_MODE_UPON_CRITICAL_ERROR
> +#define XE_WEDGED_MODE_DEFAULT_STR	"upon-critical-error"
> +
>  #define XE_BO_INVALID_OFFSET	LONG_MAX
>  
>  #define GRAPHICS_VER(xe) ((xe)->info.graphics_verx100 / 100)
> @@ -583,7 +600,7 @@ struct xe_device {
>  		/** @wedged.flag: Xe device faced a critical error and is now blocked. */
>  		atomic_t flag;
>  		/** @wedged.mode: Mode controlled by kernel parameter and debugfs */
> -		int mode;
> +		enum xe_wedged_mode mode;
>  		/** @wedged.method: Recovery method to be sent in the drm device wedged uevent */
>  		unsigned long method;
>  	} wedged;
> diff --git a/drivers/gpu/drm/xe/xe_guc_ads.c b/drivers/gpu/drm/xe/xe_guc_ads.c
> index bcb85a1bf26d..466f192b6054 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ads.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ads.c
> @@ -451,7 +451,7 @@ static void guc_policies_init(struct xe_guc_ads *ads)
>  	ads_blob_write(ads, policies.max_num_work_items,
>  		       GLOBAL_POLICY_MAX_NUM_WI);
>  
> -	if (xe->wedged.mode == 2)
> +	if (xe->wedged.mode == XE_WEDGED_MODE_UPON_ANY_HANG)
>  		global_flags |= GLOBAL_POLICY_DISABLE_ENGINE_RESET;

This mode=2 end-go is not to actually wedge 'upon any hang', but actually
to avoid resetting the GPU at any hang... like do not try to recover.

I wonder if we should and could make this explicit in the name somehow..
perhaps upon_any_hang_no_reset_attempt or upon_any_hang_no_recover_attempt...

but no strong opinion in here... just some random thoughts to make this be
more explicit.

>  
>  	ads_blob_write(ads, policies.global_flags, global_flags);
> @@ -1004,7 +1004,7 @@ int xe_guc_ads_scheduler_policy_toggle_reset(struct xe_guc_ads *ads)
>  	policies->dpc_promote_time = ads_blob_read(ads, policies.dpc_promote_time);
>  	policies->max_num_work_items = ads_blob_read(ads, policies.max_num_work_items);
>  	policies->is_valid = 1;
> -	if (xe->wedged.mode == 2)
> +	if (xe->wedged.mode == XE_WEDGED_MODE_UPON_ANY_HANG)
>  		policies->global_flags |= GLOBAL_POLICY_DISABLE_ENGINE_RESET;
>  	else
>  		policies->global_flags &= ~GLOBAL_POLICY_DISABLE_ENGINE_RESET;
> diff --git a/drivers/gpu/drm/xe/xe_guc_capture.c b/drivers/gpu/drm/xe/xe_guc_capture.c
> index 0c1fbe97b8bf..45ba0c5308ba 100644
> --- a/drivers/gpu/drm/xe/xe_guc_capture.c
> +++ b/drivers/gpu/drm/xe/xe_guc_capture.c
> @@ -1889,7 +1889,14 @@ xe_guc_capture_get_matching_and_lock(struct xe_exec_queue *q)
>  		return NULL;
>  
>  	xe = gt_to_xe(q->gt);
> -	if (xe->wedged.mode >= 2 || !xe_device_uc_enabled(xe) || IS_SRIOV_VF(xe))
> +
> +	if (xe->wedged.mode == XE_WEDGED_MODE_UPON_ANY_HANG)
> +		return NULL;
> +
> +	if (!xe_device_uc_enabled(xe))
> +		return NULL;
> +
> +	if (IS_SRIOV_VF(xe))
>  		return NULL;
>  
>  	ss = &xe->devcoredump.snapshot;
> diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
> index 7e0882074a99..4a93a2ff061f 100644
> --- a/drivers/gpu/drm/xe/xe_guc_submit.c
> +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
> @@ -998,8 +998,9 @@ void xe_guc_submit_wedge(struct xe_guc *guc)
>  	err = devm_add_action_or_reset(guc_to_xe(guc)->drm.dev,
>  				       guc_submit_wedged_fini, guc);
>  	if (err) {
> -		xe_gt_err(gt, "Failed to register clean-up on wedged.mode=2; "
> -			  "Although device is wedged.\n");
> +		xe_gt_err(gt, "Failed to register clean-up in wedged.mode=%s; "
> +			  "Although device is wedged.\n",
> +			  xe_wedged_mode_to_string(XE_WEDGED_MODE_UPON_ANY_HANG));
>  		return;
>  	}
>  
> @@ -1014,7 +1015,7 @@ static bool guc_submit_hint_wedged(struct xe_guc *guc)
>  {
>  	struct xe_device *xe = guc_to_xe(guc);
>  
> -	if (xe->wedged.mode != 2)
> +	if (xe->wedged.mode != XE_WEDGED_MODE_UPON_ANY_HANG)
>  		return false;
>  
>  	if (xe_device_wedged(xe))
> diff --git a/drivers/gpu/drm/xe/xe_module.c b/drivers/gpu/drm/xe/xe_module.c
> index d08338fc3bc1..cefd00eb7379 100644
> --- a/drivers/gpu/drm/xe/xe_module.c
> +++ b/drivers/gpu/drm/xe/xe_module.c
> @@ -10,6 +10,7 @@
>  
>  #include <drm/drm_module.h>
>  
> +#include "xe_device.h"
>  #include "xe_drv.h"
>  #include "xe_configfs.h"
>  #include "xe_hw_fence.h"
> @@ -29,7 +30,8 @@
>  #define DEFAULT_FORCE_PROBE		CONFIG_DRM_XE_FORCE_PROBE
>  #define DEFAULT_MAX_VFS			~0
>  #define DEFAULT_MAX_VFS_STR		"unlimited"
> -#define DEFAULT_WEDGED_MODE		1
> +#define DEFAULT_WEDGED_MODE		XE_WEDGED_MODE_DEFAULT
> +#define DEFAULT_WEDGED_MODE_STR		XE_WEDGED_MODE_DEFAULT_STR
>  #define DEFAULT_SVM_NOTIFIER_SIZE	512
>  
>  struct xe_modparam xe_modparam = {
> @@ -88,10 +90,10 @@ MODULE_PARM_DESC(max_vfs,
>  		 "[default=" DEFAULT_MAX_VFS_STR "])");
>  #endif
>  
> -module_param_named_unsafe(wedged_mode, xe_modparam.wedged_mode, int, 0600);
> +module_param_named_unsafe(wedged_mode, xe_modparam.wedged_mode, uint, 0600);
>  MODULE_PARM_DESC(wedged_mode,
> -		 "Module's default policy for the wedged mode (0=never, 1=upon-critical-errors, 2=upon-any-hang "
> -		 "[default=" __stringify(DEFAULT_WEDGED_MODE) "])");
> +		 "Module's default policy for the wedged mode (0=never, 1=upon-critical-error, 2=upon-any-hang "
> +		 "[default=" DEFAULT_WEDGED_MODE_STR "])");
>  
>  static int xe_check_nomodeset(void)
>  {
> diff --git a/drivers/gpu/drm/xe/xe_module.h b/drivers/gpu/drm/xe/xe_module.h
> index 5a3bfea8b7b4..1c75f38ca393 100644
> --- a/drivers/gpu/drm/xe/xe_module.h
> +++ b/drivers/gpu/drm/xe/xe_module.h
> @@ -21,7 +21,7 @@ struct xe_modparam {
>  #ifdef CONFIG_PCI_IOV
>  	unsigned int max_vfs;
>  #endif
> -	int wedged_mode;
> +	unsigned int wedged_mode;
>  	u32 svm_notifier_size;
>  };
>  
> -- 
> 2.40.0
>