Re: [PATCH 1/1] drm/xe/configfs: Allow overriding the GuC hwconfig table

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

On Wed, Nov 11, 2026 at 12:08:18AM +0000, Stuart Summers wrote:
> Add a binary configfs attribute holding a raw hwconfig blob. When set
> before bind, it is loaded into the hwconfig BO instead of querying GuC,
> so all consumers - including the DRM_XE_DEVICE_QUERY_HWCONFIG IOCTL -
> see the override. This also permits supplying a table on platforms where
> GuC exposes none, which is useful for testing userspace against
> hwconfig data the hardware does not report.

we should only put this in after we get that series that make most of
configfs as debug environments only...

> 
> Signed-off-by: Stuart Summers <stuart.summers@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_configfs.c     | 119 ++++++++++++++++++++++++++-
>  drivers/gpu/drm/xe/xe_configfs.h     |   6 ++
>  drivers/gpu/drm/xe/xe_guc_hwconfig.c |  36 +++++---
>  3 files changed, 150 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_configfs.c b/drivers/gpu/drm/xe/xe_configfs.c
> index 2ddd707a6dbd..6f810b33e12d 100644
> --- a/drivers/gpu/drm/xe/xe_configfs.c
> +++ b/drivers/gpu/drm/xe/xe_configfs.c
> @@ -63,7 +63,8 @@
>   *	    ├── engines_allowed
>   *	    ├── migrate_ulls_period_ms
>   *	    ├── enable_psmi
> - *	    └── disable_vram_page_offline
> + *	    ├── disable_vram_page_offline
> + *	    └── hwconfig
>   *
>   * After configuring the attributes as per next section, the device can be
>   * probed with::
> @@ -277,6 +278,22 @@
>   *
>   * This attribute can only be set before binding to the device.
>   *
> + * Hwconfig:
> + * ---------
> + *
> + * Override the hardware configuration table normally obtained from the GuC
> + * with a user-provided binary blob. When set, the driver uses this table in
> + * place of the GuC one everywhere it is consumed, including the table
> + * reported to userspace by the DRM_XE_DEVICE_QUERY_HWCONFIG query. This also
> + * allows a table to be provided on platforms where the GuC exposes none.
> + *
> + * The blob is the raw hwconfig table, so its size must be a multiple of 4
> + * bytes. Writing a new blob replaces the previous one::
> + *
> + *	# cat hwconfig.bin > /sys/kernel/config/xe/0000:03:00.0/hwconfig
> + *
> + * This attribute can only be set before binding to the device.
> + *
>   * Remove devices
>   * ==============
>   *
> @@ -291,6 +308,12 @@ struct wa_bb {
>  	u32 len; /* in dwords */
>  };
>  
> +/* User-provided replacement for the GuC-provided hwconfig table */
> +struct hwconfig_blob {
> +	void *data;
> +	size_t len; /* in bytes */
> +};
> +
>  struct xe_config_group_device {
>  	struct config_group group;
>  	struct config_group sriov;
> @@ -299,6 +322,7 @@ struct xe_config_group_device {
>  		u64 gt_types_allowed;
>  		u64 engines_allowed;
>  		u32 migrate_ulls_period_ms;
> +		struct hwconfig_blob hwconfig;
>  		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;
> @@ -937,6 +961,50 @@ 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);
>  }
>  
> +static ssize_t hwconfig_read(struct config_item *item, void *buf, size_t count)
> +{
> +	struct xe_config_group_device *dev = to_xe_config_group_device(item);
> +
> +	guard(mutex)(&dev->lock);
> +
> +	if (!buf)
> +		return dev->config.hwconfig.len;
> +
> +	count = min(count, dev->config.hwconfig.len);
> +	memcpy(buf, dev->config.hwconfig.data, count);
> +
> +	return count;
> +}
> +
> +static ssize_t hwconfig_write(struct config_item *item, const void *buf, size_t count)
> +{
> +	struct xe_config_group_device *dev = to_xe_config_group_device(item);
> +	void *data = NULL;
> +
> +	/* The table is a sequence of dwords */
> +	if (count % sizeof(u32))
> +		return -EINVAL;
> +
> +	if (count) {
> +		data = kmemdup(buf, count, GFP_KERNEL);
> +		if (!data)
> +			return -ENOMEM;
> +	}
> +
> +	guard(mutex)(&dev->lock);
> +
> +	if (is_bound(dev)) {
> +		kfree(data);
> +		return -EBUSY;
> +	}
> +
> +	kfree(dev->config.hwconfig.data);
> +	dev->config.hwconfig.data = data;
> +	dev->config.hwconfig.len = count;
> +
> +	return count;
> +}
> +
>  CONFIGFS_ATTR(, ctx_restore_mid_bb);
>  CONFIGFS_ATTR(, ctx_restore_post_bb);
>  CONFIGFS_ATTR(, enable_multi_queue);
> @@ -946,6 +1014,7 @@ CONFIGFS_ATTR(, disable_vram_page_offline);
>  CONFIGFS_ATTR(, engines_allowed);
>  CONFIGFS_ATTR(, gt_types_allowed);
>  CONFIGFS_ATTR(, survivability_mode);
> +CONFIGFS_BIN_ATTR(, hwconfig, NULL, SZ_64K);
>  
>  static struct configfs_attribute *xe_config_device_attrs[] = {
>  	&attr_ctx_restore_mid_bb,
> @@ -960,12 +1029,18 @@ static struct configfs_attribute *xe_config_device_attrs[] = {
>  	NULL,
>  };
>  
> +static const struct configfs_bin_attribute *const xe_config_device_bin_attrs[] = {
> +	&attr_hwconfig,
> +	NULL,
> +};
> +
>  static void xe_config_device_release(struct config_item *item)
>  {
>  	struct xe_config_group_device *dev = to_xe_config_group_device(item);
>  
>  	mutex_destroy(&dev->lock);
>  
> +	kfree(dev->config.hwconfig.data);
>  	kfree(dev->config.ctx_restore_mid_bb[0].cs);
>  	kfree(dev->config.ctx_restore_post_bb[0].cs);
>  	kfree(dev);
> @@ -1001,6 +1076,7 @@ static const struct config_item_type xe_config_device_type = {
>  	.ct_item_ops	= &xe_config_device_ops,
>  	.ct_group_ops	= &xe_config_device_group_ops,
>  	.ct_attrs	= xe_config_device_attrs,
> +	.ct_bin_attrs	= xe_config_device_bin_attrs,
>  	.ct_owner	= THIS_MODULE,
>  };
>  
> @@ -1243,6 +1319,10 @@ static void dump_custom_dev_config(struct pci_dev *pdev,
>  	PRI_CUSTOM_ATTR("%u", sriov.admin_only_pf);
>  
>  #undef PRI_CUSTOM_ATTR
> +
> +	if (dev->config.hwconfig.len)
> +		pci_info(pdev, "configfs: hwconfig = %zu bytes\n",
> +			 dev->config.hwconfig.len);
>  }
>  
>  /**
> @@ -1479,6 +1559,43 @@ u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev,
>  	return len;
>  }
>  
> +/**
> + * xe_configfs_get_hwconfig - get a copy of the configfs hwconfig blob
> + * @pdev: pci device
> + * @blob: pointer to store the newly allocated copy of the blob
> + *
> + * If a hwconfig table override was written to configfs for @pdev, allocate a
> + * copy of it and store the pointer in @blob. The caller takes ownership of it
> + * and is responsible for freeing it with kfree().
> + *
> + * Return: size in bytes of the blob stored in @blob, or 0 if no override is
> + *     set or it could not be copied.
> + */
> +size_t xe_configfs_get_hwconfig(struct pci_dev *pdev, void **blob)
> +{
> +	struct xe_config_group_device *dev = find_xe_config_group_device(pdev);
> +	size_t len = 0;
> +
> +	*blob = NULL;
> +
> +	if (!dev)
> +		return 0;
> +
> +	scoped_guard(mutex, &dev->lock) {
> +		if (!dev->config.hwconfig.len)
> +			break;
> +
> +		*blob = kmemdup(dev->config.hwconfig.data,
> +				dev->config.hwconfig.len, GFP_KERNEL);
> +		if (*blob)
> +			len = dev->config.hwconfig.len;
> +	}
> +
> +	config_group_put(&dev->group);
> +
> +	return len;
> +}
> +
>  #ifdef CONFIG_PCI_IOV
>  /**
>   * xe_configfs_admin_only_pf() - Get PF's operational mode.
> diff --git a/drivers/gpu/drm/xe/xe_configfs.h b/drivers/gpu/drm/xe/xe_configfs.h
> index 327b648944ff..526250e9fdfe 100644
> --- a/drivers/gpu/drm/xe/xe_configfs.h
> +++ b/drivers/gpu/drm/xe/xe_configfs.h
> @@ -32,6 +32,7 @@ u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev,
>  u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev,
>  					enum xe_engine_class class,
>  					const u32 **cs);
> +size_t xe_configfs_get_hwconfig(struct pci_dev *pdev, void **blob);
>  #ifdef CONFIG_PCI_IOV
>  unsigned int xe_configfs_get_max_vfs(struct pci_dev *pdev);
>  bool xe_configfs_admin_only_pf(struct pci_dev *pdev);
> @@ -54,6 +55,11 @@ static inline u32 xe_configfs_get_ctx_restore_mid_bb(struct pci_dev *pdev,
>  static inline u32 xe_configfs_get_ctx_restore_post_bb(struct pci_dev *pdev,
>  						      enum xe_engine_class class,
>  						      const u32 **cs) { return 0; }
> +static inline size_t xe_configfs_get_hwconfig(struct pci_dev *pdev, void **blob)
> +{
> +	*blob = NULL;
> +	return 0;
> +}
>  #ifdef CONFIG_PCI_IOV
>  static inline unsigned int xe_configfs_get_max_vfs(struct pci_dev *pdev)
>  {
> diff --git a/drivers/gpu/drm/xe/xe_guc_hwconfig.c b/drivers/gpu/drm/xe/xe_guc_hwconfig.c
> index dc667a71b438..33abfdfcff41 100644
> --- a/drivers/gpu/drm/xe/xe_guc_hwconfig.c
> +++ b/drivers/gpu/drm/xe/xe_guc_hwconfig.c
> @@ -10,7 +10,9 @@
>  
>  #include "abi/guc_actions_abi.h"
>  #include "xe_bo.h"
> +#include "xe_configfs.h"
>  #include "xe_device_types.h"
> +#include "xe_gt_printk.h"
>  #include "xe_gt_types.h"
>  #include "xe_guc.h"
>  #include "xe_map.h"
> @@ -55,6 +57,7 @@ int xe_guc_hwconfig_init(struct xe_guc *guc)
>  	struct xe_gt *gt = guc_to_gt(guc);
>  	struct xe_tile *tile = gt_to_tile(gt);
>  	struct xe_bo *bo;
> +	void *blob;
>  	u32 size;
>  	int err;
>  
> @@ -68,25 +71,38 @@ int xe_guc_hwconfig_init(struct xe_guc *guc)
>  	if (gt != xe_root_mmio_gt(xe))
>  		return 0;
>  
> -	/* ADL_P, DG2+ supports hwconfig table */
> -	if (GRAPHICS_VERx100(xe) < 1255 && xe->info.platform != XE_ALDERLAKE_P)
> -		return 0;
> -
> -	err = guc_hwconfig_size(guc, &size);
> -	if (err)
> -		return err;
> -	if (!size)
> -		return -EINVAL;
> +	size = xe_configfs_get_hwconfig(to_pci_dev(xe->drm.dev), &blob);
> +	if (!size) {
> +		/* ADL_P, DG2+ supports hwconfig table */
> +		if (GRAPHICS_VERx100(xe) < 1255 && xe->info.platform != XE_ALDERLAKE_P)
> +			return 0;
> +
> +		err = guc_hwconfig_size(guc, &size);
> +		if (err)
> +			return err;
> +		if (!size)
> +			return -EINVAL;
> +	}
>  
>  	bo = xe_managed_bo_create_pin_map(xe, tile, PAGE_ALIGN(size),
>  					  XE_BO_FLAG_SYSTEM |
>  					  XE_BO_FLAG_GGTT |
>  					  XE_BO_FLAG_GGTT_INVALIDATE);
> -	if (IS_ERR(bo))
> +	if (IS_ERR(bo)) {
> +		kfree(blob);
>  		return PTR_ERR(bo);
> +	}
>  	guc->hwconfig.bo = bo;
>  	guc->hwconfig.size = size;
>  
> +	if (blob) {
> +		xe_map_memcpy_to(xe, &bo->vmap, 0, blob, size);
> +		kfree(blob);
> +		xe_gt_info(gt, "Using hwconfig table override from configfs (%u bytes)\n",
> +			   size);
> +		return 0;
> +	}
> +
>  	return guc_hwconfig_copy(guc);
>  }
>  
> -- 
> 2.43.0
>