Re: [RFC PATCH V7 10/10] drm/xe/cri: Add sysfs interface for bad gpu vram pages

[Matthew Auld <matthew.auld@intel.com>]

On 16/04/2026 08:49, Tejas Upadhyay wrote:
> Starting CRI, Include a sysfs interface designed to expose information
> about bad VRAM pages—those identified as having hardware faults
> (e.g., ECC errors). This interface allows userspace tools and
> administrators to monitor the health of the GPU's local memory and
> track the status of page retirement.To get details on bad gpu vram
> pages can be found under /sys/bus/pci/devices/bdf/vram_bad_pages.
> 
> Where The format is, pfn : gpu page size : flags

With "gpu page size" this is really just the min block size? 
gpu-page-size is normally interpreted as GTT page size, which is a 
different thing. But is that not always 4K here? Since that is the 
granularity of the addr reservation? Is it useful to print that? Is 
knowing that pfn x is offlined not enough?

Also what is the story if you have multiple VRAM instances here? There 
is only one vram_bad_pages file? Would this treat VRAM as one giant 
unified thing?

> 
> flags:
> R: reserved, this gpu page is reserved.
> P: pending for reserve, this gpu page is marked as bad, will be reserved
>     in next window of page_reserve.
> F: unable to reserve. this gpu page can’t be reserved due to some reasons.
> 
> For example if you read using cat /sys/bus/pci/devices/bdf/vram_bad_pages,
> max_pages : 10000
> 0x00000000 : 0x00001000 : R
> 0x00001234 : 0x00001000 : P
> 
> v3:
> - Move FW communication in RAS code
> v2:
> - Add max_pages info as per updated design doc
> - Rebase
> 
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_device_sysfs.c       |  7 ++
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c       | 79 ++++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.h       |  1 +
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h |  2 +
>   4 files changed, 89 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_device_sysfs.c b/drivers/gpu/drm/xe/xe_device_sysfs.c
> index a73e0e957cb0..47c5be4180fe 100644
> --- a/drivers/gpu/drm/xe/xe_device_sysfs.c
> +++ b/drivers/gpu/drm/xe/xe_device_sysfs.c
> @@ -8,12 +8,14 @@
>   #include <linux/pci.h>
>   #include <linux/sysfs.h>
>   
> +#include "xe_configfs.h"
>   #include "xe_device.h"
>   #include "xe_device_sysfs.h"
>   #include "xe_mmio.h"
>   #include "xe_pcode_api.h"
>   #include "xe_pcode.h"
>   #include "xe_pm.h"
> +#include "xe_ttm_vram_mgr.h"
>   
>   /**
>    * DOC: Xe device sysfs
> @@ -267,6 +269,7 @@ static const struct attribute_group auto_link_downgrade_attr_group = {
>   int xe_device_sysfs_init(struct xe_device *xe)
>   {
>   	struct device *dev = xe->drm.dev;
> +	bool policy;
>   	int ret;
>   
>   	if (xe->d3cold.capable) {
> @@ -285,5 +288,9 @@ int xe_device_sysfs_init(struct xe_device *xe)
>   			return ret;
>   	}
>   
> +	policy = xe_configfs_get_bad_page_reservation(to_pci_dev(dev));
> +	if (xe->info.platform == XE_CRESCENTISLAND && policy)
> +		xe_ttm_vram_sysfs_init(xe);
> +
>   	return 0;
>   }
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index 7f58e7e8c3e1..611d945c9eb4 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -760,3 +760,82 @@ int xe_ttm_vram_handle_addr_fault(struct xe_device *xe, unsigned long addr)
>   	return ret;
>   }
>   EXPORT_SYMBOL(xe_ttm_vram_handle_addr_fault);
> +
> +static void xe_ttm_vram_dump_bad_pages_info(char *buf, struct xe_ttm_vram_mgr *mgr)
> +{
> +	const unsigned int element_size = sizeof("0xabcdabcd : 0x12345678 : R\n") - 1;
> +	const unsigned int maxpage_size = sizeof("max_pages: 10000\n") - 1;
> +	struct xe_ttm_vram_offline_resource *pos, *n;
> +	struct gpu_buddy_block *block;
> +	ssize_t s = 0;
> +
> +	mutex_lock(&mgr->lock);
> +	s += scnprintf(&buf[s], maxpage_size + 1, "max_pages: %d\n", mgr->max_pages);
> +	list_for_each_entry_safe(pos, n, &mgr->offlined_pages, offlined_link) {
> +		block = list_first_entry(&pos->blocks,
> +					 struct gpu_buddy_block,
> +					 link);
> +		s += scnprintf(&buf[s], element_size + 1,
> +			       "0x%08llx : 0x%08llx : %1s\n",
> +			       gpu_buddy_block_offset(block) >> PAGE_SHIFT,
> +			       gpu_buddy_block_size(&mgr->mm, block),
> +			       "R");
> +	}
> +	list_for_each_entry_safe(pos, n, &mgr->queued_pages, queued_link) {
> +		block = list_first_entry(&pos->blocks,
> +					 struct gpu_buddy_block,
> +					 link);
> +		s += scnprintf(&buf[s], element_size + 1,
> +			       "0x%08llx : 0x%08llx : %1s\n",
> +			       gpu_buddy_block_offset(block) >> PAGE_SHIFT,
> +			       gpu_buddy_block_size(&mgr->mm, block),
> +			       pos->status ? "P" : "F");
> +	}
> +	mutex_unlock(&mgr->lock);
> +}
> +
> +static ssize_t vram_bad_pages_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	struct xe_device *xe = pdev_to_xe_device(pdev);
> +	struct ttm_resource_manager *man;
> +	struct xe_ttm_vram_mgr *mgr;
> +
> +	man = ttm_manager_type(&xe->ttm, XE_PL_VRAM0);
> +	if (man) {
> +		mgr = to_xe_ttm_vram_mgr(man);
> +		xe_ttm_vram_dump_bad_pages_info(buf, mgr);
> +	}
> +
> +	return sysfs_emit(buf, "%s\n", buf);
> +}
> +static DEVICE_ATTR_RO(vram_bad_pages);
> +
> +static void xe_ttm_vram_sysfs_fini(void *arg)
> +{
> +	struct xe_device *xe = arg;
> +
> +	device_remove_file(xe->drm.dev, &dev_attr_vram_bad_pages);
> +}
> +
> +/**
> + * xe_ttm_vram_sysfs_init - Initialize vram sysfs component
> + * @tile: Xe Tile object
> + *
> + * It needs to be initialized after the main tile component is ready
> + *
> + * Returns: 0 on success, negative error code on error.
> + */
> +int xe_ttm_vram_sysfs_init(struct xe_device *xe)
> +{
> +	int err;
> +
> +	err = device_create_file(xe->drm.dev, &dev_attr_vram_bad_pages);
> +	if (err) {
> +		dev_err(xe->drm.dev, "Failed to create vram_bad_pages sysfs file: %d\n", err);
> +		return 0;
> +	}
> +
> +	return devm_add_action_or_reset(xe->drm.dev, xe_ttm_vram_sysfs_fini, xe);
> +}
> +EXPORT_SYMBOL(xe_ttm_vram_sysfs_init);
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h
> index 8ef06d9d44f7..c33e1a8d9217 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.h
> @@ -32,6 +32,7 @@ void xe_ttm_vram_get_used(struct ttm_resource_manager *man,
>   			  u64 *used, u64 *used_visible);
>   
>   int xe_ttm_vram_handle_addr_fault(struct xe_device *xe, unsigned long addr);
> +int xe_ttm_vram_sysfs_init(struct xe_device *xe);
>   static inline struct xe_ttm_vram_mgr_resource *
>   to_xe_ttm_vram_mgr_resource(struct ttm_resource *res)
>   {
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h b/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> index 07ed88b47e04..b23796066a1a 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> @@ -39,6 +39,8 @@ struct xe_ttm_vram_mgr {
>   	u32 mem_type;
>   	/** @offline_mode: debugfs hook for setting page offline mode */
>   	u64 offline_mode;
> +	/** @max_pages: max pages that can be in offline queue retrieved from FW */
> +	u16 max_pages;
>   };
>   
>   /**