RE: [PATCH V16 10/12] drm/xe: Add sysfs interface for bad gpu vram pages

> -----Original Message-----
> From: Wajdeczko, Michal <[email protected]>
> Sent: 17 August 2026 16:57
> To: Upadhyay, Tejas <[email protected]>; intel-
> [email protected]; Vivi, Rodrigo <[email protected]>; Thomas
> Hellström <[email protected]>
> Cc: Ghimiray, Himal Prasad <[email protected]>
> Subject: Re: [PATCH V16 10/12] drm/xe: Add sysfs interface for bad gpu vram
> pages
> 
> 
> 
> On 8/17/2026 8:51 AM, Tejas Upadhyay wrote:
> > 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. Details on bad gpu vram pages can be found under
> > /sys/bus/pci/devices/<bdf>/vram_bad_pages.
> 
> since those new files are xe driver specific, shouldn't we refer to them using
> 
> 	/sys/bus/pci/drivers/xe/<bdf>/vram...
> 
> >
> > The format is: pfn : gpu_page_size : flags
> 
> kernel documentation [1] says
> 
> 	"Mixing types, expressing multiple lines of data, and doing
> 	fancy formatting of data is heavily frowned upon"
> 
> [1] https://docs.kernel.org/filesystems/sysfs.html#attributes
> 
> so to follow the guidelines maybe we expose the separate files:
> 
> /sys/bus/pci/drivers/xe/<bdf>/vram_page_size		u64
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_count	u64
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_reserved	u64[]
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_pending	u64[]
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_failed	u64[]
> 
> or
> 
> /sys/bus/pci/drivers/xe/<bdf>
> |
> +-- vram/
>     +-- page_size	u64
>     +-- bad_pages/
>         +-- count	u64
>         +-- reserved	u64[]
>         +-- pending	u64[]
>         +-- failed	u64[]
> 
> then
> 
> /sys/bus/pci/drivers/xe/<bdf>/vram_page_size:0x1000
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_count:5
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_reserved:0x000000000000
> 0000
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_pending:0x0000000001234
> 000
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_pending:0x0000000001235
> 000
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_pending:0x0000000001236
> 000
> /sys/bus/pci/drivers/xe/<bdf>/vram_bad_pages_pending:0x0000000001237
> 000

Thanks for comment, this is documented format by design doc. Sysman also depending on this format. So I don’t see this can be done without design being changed for everyone.

Tejas
> 
> >
> > 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, cat /sys/bus/pci/devices/<bdf>/vram_bad_pages:
> >   max_pages : 10000
> >   0x0000000000000000 : 0x0000000000001000 : R
> >   0x0000000000001234 : 0x0000000000001000 : P
> >
> > The sysfs binary attribute is created under the PCI device kobject
> > when the platform supports it and the configfs bad_page_reservation
> > policy is enabled. Uses RCU-protected list traversal so reads never
> > block normal VRAM allocation operations.
> >
> > Signed-off-by: Tejas Upadhyay <[email protected]>
> > ---
> >  drivers/gpu/drm/xe/xe_device_sysfs.c       |   7 +
> >  drivers/gpu/drm/xe/xe_ttm_vram_mgr.c       | 141
> +++++++++++++++++++++
> >  drivers/gpu/drm/xe/xe_ttm_vram_mgr.h       |   1 +
> >  drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h |   2 +
> >  4 files changed, 151 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 a48196ce303f..73cd06c22d37 100644
> > --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> > +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> > @@ -820,3 +820,144 @@ int xe_ttm_vram_handle_addr_fault(struct
> xe_device *xe, u64 addr)
> >  	return xe_ttm_vram_reserve_page_at_addr(xe, addr - vr->dpa_base,
> > vram_mgr, mm);  }  EXPORT_SYMBOL(xe_ttm_vram_handle_addr_fault);
> > +
> > +static size_t serialize_bad_pages(struct xe_ttm_vram_mgr *mgr, char
> > +*buf, size_t max_len) {
> > +	struct xe_ttm_vram_offline_resource *pos;
> > +	struct gpu_buddy_block *block;
> > +	size_t s = 0;
> > +	int printed;
> > +	int count = 0;
> > +
> > +	rcu_read_lock();
> > +
> > +	printed = scnprintf(buf + s, max_len - s, "max_pages: %d\n", mgr-
> >max_pages);
> > +	s += printed;
> > +
> > +	list_for_each_entry_rcu(pos, &mgr->offlined_pages, offlined_link) {
> > +		if (count >= 10000 || s >= max_len)
> > +			break;
> > +
> > +		block = list_first_entry_or_null(&pos->blocks, struct
> gpu_buddy_block, link);
> > +		if (!block)
> > +			continue;
> > +
> > +		printed = scnprintf(buf + s, max_len - s, "0x%016llx : 0x%016llx
> : %c\n",
> > +				    gpu_buddy_block_offset(block) >>
> PAGE_SHIFT,
> > +				    gpu_buddy_block_size(&mgr->mm, block),
> 'R');
> > +		s += printed;
> > +		count++;
> > +	}
> > +	list_for_each_entry_rcu(pos, &mgr->queued_pages, queued_link) {
> > +		u64 pfn, blk_size;
> > +
> > +		if (count >= 10000 || s >= max_len)
> > +			break;
> > +
> > +		block = list_first_entry_or_null(&pos->blocks, struct
> gpu_buddy_block, link);
> > +		if (block) {
> > +			pfn = gpu_buddy_block_offset(block) >> PAGE_SHIFT;
> > +			blk_size = gpu_buddy_block_size(&mgr->mm, block);
> > +		} else {
> > +			pfn = pos->addr >> PAGE_SHIFT;
> > +			blk_size = PAGE_SIZE;
> > +		}
> > +
> > +		printed = scnprintf(buf + s, max_len - s, "0x%016llx : 0x%016llx
> : %c\n",
> > +				    pfn, blk_size, pos->status ? 'F' : 'P');
> > +		s += printed;
> > +		count++;
> > +	}
> > +
> > +	rcu_read_unlock();
> > +	return s;
> > +}
> > +
> > +static ssize_t vram_bad_pages_bin_read(struct file *filp, struct kobject
> *kobj,
> > +				       const struct bin_attribute *attr, char *buf,
> > +				       loff_t off, size_t count)
> > +{
> > +	struct device *dev = kobj_to_dev(kobj);
> > +	struct pci_dev *pdev = to_pci_dev(dev);
> > +	struct ttm_resource_manager *man;
> > +	struct xe_ttm_vram_mgr *mgr;
> > +	size_t allocation_size;
> > +	struct xe_device *xe;
> > +	size_t full_data_len;
> > +	int active_entries;
> > +	char *temp_buf;
> > +
> > +	xe = pdev_to_xe_device(pdev);
> > +	man = ttm_manager_type(&xe->ttm, XE_PL_VRAM0);
> > +	if (!man)
> > +		return -ENODEV;
> > +	mgr = to_xe_ttm_vram_mgr(man);
> > +
> > +	active_entries = READ_ONCE(mgr->n_offlined_pages) +
> > +READ_ONCE(mgr->n_queued_pages);
> > +
> > +	if (active_entries > 10000)
> > +		active_entries = 10000;
> > +
> > +	allocation_size = 64 + (active_entries * 48);
> > +
> > +	temp_buf = kvmalloc(allocation_size, GFP_KERNEL);
> > +	if (!temp_buf)
> > +		return -ENOMEM;
> > +
> > +	/* serialize_bad_pages uses rcu_read_lock internally */
> > +	full_data_len = serialize_bad_pages(mgr, temp_buf, allocation_size);
> > +
> > +	if (off >= full_data_len) {
> > +		kvfree(temp_buf);
> > +		return 0;
> > +	}
> > +
> > +	if (off + count > full_data_len)
> > +		count = full_data_len - off;
> > +
> > +	memcpy(buf, temp_buf + off, count);
> > +
> > +	kvfree(temp_buf);
> > +	return count;
> > +}
> > +
> > +static const struct bin_attribute bin_attr_vram_bad_pages = {
> > +	.attr = { .name = "vram_bad_pages", .mode = 0444 },
> > +	.read = vram_bad_pages_bin_read,
> > +	.size = 0,
> > +};
> > +
> > +static void xe_ttm_vram_sysfs_fini(void *arg) {
> > +	struct xe_device *xe = arg;
> > +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> > +
> > +	sysfs_remove_bin_file(&pdev->dev.kobj,
> &bin_attr_vram_bad_pages); }
> > +
> > +/**
> > + * xe_ttm_vram_sysfs_init - Initialize vram bad pages sysfs binary
> > +file
> > + * @xe: Xe Device object
> > + *
> > + * Creates a binary sysfs file under the PCI device for reading
> > + * offlined and queued VRAM pages. Supports large entry counts
> > + * via offset/count pagination.
> > + *
> > + * Returns: 0 on success, negative error code on error.
> > + */
> > +int xe_ttm_vram_sysfs_init(struct xe_device *xe) {
> > +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> > +	int err;
> > +
> > +	err = sysfs_create_bin_file(&pdev->dev.kobj,
> &bin_attr_vram_bad_pages);
> > +	if (err) {
> > +		dev_err(&pdev->dev,
> > +			"Failed to create vram_bad_pages sysfs: %d\n",
> > +			err);
> > +		return err;
> > +	}
> > +
> > +	return devm_add_action_or_reset(&pdev->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 d5392beff30c..eb55b0f74ef3 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, u64 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 dc97b0ad0e51..efcf3e1d4e80 100644
> > --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> > +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> > @@ -37,6 +37,8 @@ struct xe_ttm_vram_mgr {
> >  	struct mutex lock;
> >  	/** @mem_type: The TTM memory type */
> >  	u32 mem_type;
> > +	/** @max_pages: max pages that can be in offline queue retrieved
> from FW */
> > +	u16 max_pages;
> >  };
> >
> >  /**