Re: [PATCH v5 7/7] drm/xe/configfs: Add mid context restore bb

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

On Tue, Sep 16, 2025 at 02:15:44PM -0700, Lucas De Marchi wrote:
> Like done for post context restore, allow the user to add commands to
> the middle of context restore, at the beginning of engine restore
> commands.
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_configfs.c | 46 ++++++++++++++++++++++++++++++++++++----
>  1 file changed, 42 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
> index 90bc5a4b5da71..640df5bee4579 100644
> --- a/drivers/gpu/drm/xe/xe_configfs.c
> +++ b/drivers/gpu/drm/xe/xe_configfs.c
> @@ -126,13 +126,21 @@
>   * not intended for normal execution and will taint the kernel with TAINT_TEST
>   * when used.
>   *
> - * Currently this is implemented only for post context restore. Examples:
> + * Currently this is implemented only for post and mid context restore.
> + * Examples:
>   *
> - * #. Execute a LRI command to write 0xDEADBEEF to register 0x4f10::
> + * #. Execute a LRI command to write 0xDEADBEEF to register 0x4f10 after the
> + *    normal context restore::
>   *
>   *	# echo 'rcs cmd 11000001 4F100 DEADBEEF' \
>   *		> /sys/kernel/config/xe/0000:03:00.0/ctx_restore_post_bb
>   *
> + * #. Execute a LRI command to write 0xDEADBEEF to register 0x4f10 at the
> + *    beginning of the context restore::
> + *
> + *	# echo 'rcs cmd 11000001 4F100 DEADBEEF' \
> + *		> /sys/kernel/config/xe/0000:03:00.0/ctx_restore_mid_bb
> +
>   * #. Load certain values in a couple of registers (it can be used as a simpler
>   *    alternative to the `cmd`) action::
>   *
> @@ -146,7 +154,7 @@
>   *       When using multiple lines, make sure to use a command that is
>   *       implemented with a single write syscall, like HEREDOC.
>   *
> - * This attribute can only be set before binding to the device.
> + * These attributes can only be set before binding to the device.
>   *
>   * Remove devices
>   * ==============
> @@ -168,6 +176,7 @@ struct xe_config_group_device {
>  	struct xe_config_device {
>  		u64 engines_allowed;
>  		struct wa_bb ctx_restore_post_bb[XE_ENGINE_CLASS_MAX];
> +		struct wa_bb ctx_restore_mid_bb[XE_ENGINE_CLASS_MAX];
>  		bool survivability_mode;
>  		bool enable_psmi;
>  	} config;
> @@ -467,6 +476,13 @@ static ssize_t wa_bb_show(struct xe_config_group_device *dev,
>  	return p - data;
>  }
>  
> +static ssize_t ctx_restore_mid_bb_show(struct config_item *item, char *page)
> +{
> +	struct xe_config_group_device *dev = to_xe_config_group_device(item);
> +
> +	return wa_bb_show(dev, dev->config.ctx_restore_mid_bb, page, SZ_4K);
> +}
> +
>  static ssize_t ctx_restore_post_bb_show(struct config_item *item, char *page)
>  {
>  	struct xe_config_group_device *dev = to_xe_config_group_device(item);
> @@ -623,6 +639,14 @@ static ssize_t wa_bb_store(struct wa_bb wa_bb[static XE_ENGINE_CLASS_MAX],
>  	return len;
>  }
>  
> +static ssize_t ctx_restore_mid_bb_store(struct config_item *item,
> +					const char *data, size_t sz)
> +{
> +	struct xe_config_group_device *dev = to_xe_config_group_device(item);
> +
> +	return wa_bb_store(dev->config.ctx_restore_mid_bb, dev, data, sz);
> +}
> +
>  static ssize_t ctx_restore_post_bb_store(struct config_item *item,
>  					 const char *data, size_t sz)
>  {
> @@ -631,12 +655,14 @@ static ssize_t ctx_restore_post_bb_store(struct config_item *item,
>  	return wa_bb_store(dev->config.ctx_restore_post_bb, dev, data, sz);
>  }
>  
> +CONFIGFS_ATTR(, ctx_restore_mid_bb);
>  CONFIGFS_ATTR(, ctx_restore_post_bb);
>  CONFIGFS_ATTR(, enable_psmi);
>  CONFIGFS_ATTR(, engines_allowed);
>  CONFIGFS_ATTR(, survivability_mode);
>  
>  static struct configfs_attribute *xe_config_device_attrs[] = {
> +	&attr_ctx_restore_mid_bb,
>  	&attr_ctx_restore_post_bb,
>  	&attr_enable_psmi,
>  	&attr_engines_allowed,
> @@ -909,7 +935,19 @@ u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev,
>  				       enum xe_engine_class class,
>  				       const u32 **cs)
>  {
> -	return 0;
> +	struct xe_config_group_device *dev = find_xe_config_group_device(pdev);
> +	u32 len;
> +
> +	if (!dev)
> +		return 0;
> +
> +	if (cs)
> +		*cs = dev->config.ctx_restore_mid_bb[class].cs;
> +
> +	len = dev->config.ctx_restore_mid_bb[class].len;
> +	config_group_put(&dev->group);
> +
> +	return len;
>  }
>  
>  /**
> 
> -- 
> 2.50.1
>