Re: [PATCH 2/2] drm/xe/cri: Expose device UUID through sysfs

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

On Mon, Sep 07, 2026 at 05:48:12PM +0200, Michal Wajdeczko wrote:
>
>
> On 9/7/2026 2:04 PM, Gupta, Anshuman wrote:
> >
> >
> >> -----Original Message-----
> >> From: Wajdeczko, Michal <michal.wajdeczko@intel.com>
> >> Sent: Monday, September 7, 2026 5:25 PM
> >> To: Nilawar, Badal <badal.nilawar@intel.com>; intel-
> >> xe@lists.freedesktop.org; Vivi, Rodrigo <rodrigo.vivi@intel.com>
> >> Cc: Gupta, Anshuman <anshuman.gupta@intel.com>; Jadav, Raag
> >> <raag.jadav@intel.com>; Tauro, Riana <riana.tauro@intel.com>; Koujalagi,
> >> Mallesh <mallesh.koujalagi@intel.com>; Iddamsetty, Aravind
> >> <aravind.iddamsetty@intel.com>; heikki.krogerus@linux.intel.com;
> >> Ghimiray, Himal Prasad <himal.prasad.ghimiray@intel.com>
> >> Subject: Re: [PATCH 2/2] drm/xe/cri: Expose device UUID through sysfs

s/uuid/uid everywhere please. It is only a 64bit, not a 128.

> >>
> >>
> >>
> >> On 9/7/2026 11:13 AM, Nilawar, Badal wrote:
> >>>
> >>> On 04-09-2026 22:07, Michal Wajdeczko wrote:
> >>>>
> >>>> On 9/4/2026 6:06 PM, Badal Nilawar wrote:
> >>>>> Expose a read-only sysfs attribute, device_uuid, that reports the
> >>>>> GPU's unique hardware identifier.
> >>>>>
> >>>> Bspec: 53048,53049
> >>> Sure
> >>>>
> >>>>> Assisted-by: Claude:claude-opus-4.8
> >>>>> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> >>>>> ---
> >>>>>   .../ABI/testing/sysfs-driver-intel-xe-gpu     | 10 ++++++
> >>>>>   drivers/gpu/drm/xe/regs/xe_regs.h             |  2 ++
> >>>>>   drivers/gpu/drm/xe/xe_device.c                |  3 ++
> >>>>>   drivers/gpu/drm/xe/xe_device_sysfs.c          | 36
> >>>>> +++++++++++++++++++
> >>>>>   drivers/gpu/drm/xe/xe_device_types.h          |  3 ++
> >>>>>   5 files changed, 54 insertions(+)
> >>>>>   create mode 100644
> >>>>> Documentation/ABI/testing/sysfs-driver-intel-xe-gpu
> >>>>>
> >>>>> diff --git a/Documentation/ABI/testing/sysfs-driver-intel-xe-gpu
> >>>>> b/Documentation/ABI/testing/sysfs-driver-intel-xe-gpu
> >>>>> new file mode 100644
> >>>>> index 000000000000..1a4bdfbad8d7
> >>>>> --- /dev/null
> >>>>> +++ b/Documentation/ABI/testing/sysfs-driver-intel-xe-gpu
> >>>>> @@ -0,0 +1,10 @@
> >>>>> +What:        /sys/bus/pci/drivers/xe/.../device_uuid
> >>>>> +Date:        September 2026
> >>>>> +KernelVersion:    7.4
> >>>>> +Contact:    intel-xe@lists.freedesktop.org
> >>>>> +Description:    RO. Unique 64-bit identifier of the device
> >>>>> +instance, read from
> >>>>> +        the device's CRI_DEVICE_UUID register and printed as a
> >>>> hmm, maybe in the user facing documentation we should refer to this
> >>>> register as
> >>>>
> >>>>     DEVICE_UUID(102008)
> >>>>
> >>>> instead of the meaningless macro name?
> >>> I will drop "read from ..." statement.
> >>>>
> >>>>> +        zero-padded 16-digit hexadecimal string.
> >>>> if this is UUID, shouldn't we print it in UUID format? see %pU
> >>> I this is not UUID, i will rename the node as device_uid.
> >>>>
> >>>>> +
> >>>>> +        This sysfs file is present only on Intel Xe platforms that
> >>>>> +        provide a device UUID. It is available to all users.
> >>>>> diff --git a/drivers/gpu/drm/xe/regs/xe_regs.h
> >>>>> b/drivers/gpu/drm/xe/regs/xe_regs.h
> >>>>> index ef4746b7b5d3..68226fe0b659 100644
> >>>>> --- a/drivers/gpu/drm/xe/regs/xe_regs.h
> >>>>> +++ b/drivers/gpu/drm/xe/regs/xe_regs.h
> >>>>> @@ -30,6 +30,8 @@
> >>>>>   #define XEHP_MTCFG_ADDR                XE_REG(0x101800)
> >>>>>   #define   TILE_COUNT                REG_GENMASK(15, 8)
> >>>>>   +#define CRI_DEVICE_UUID                XE_REG(0x102008)
> >>>>> +
> >>>>>   #define GGC                    XE_REG(0x108040)
> >>>>>   #define   GMS_MASK                REG_GENMASK(15, 8)
> >>>>>   #define   GGMS_MASK                REG_GENMASK(7, 6) diff --git
> >>>>> a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
> >>>>> index 8583b2e9ecf4..e8db8871990b 100644
> >>>>> --- a/drivers/gpu/drm/xe/xe_device.c
> >>>>> +++ b/drivers/gpu/drm/xe/xe_device.c
> >>>>> @@ -801,6 +801,9 @@ int xe_device_probe_early(struct xe_device *xe)
> >>>>>       if (IS_SRIOV_VF(xe))
> >>>>>           vf_update_device_info(xe);
> >>>>>   +    if (xe->info.platform == XE_CRESCENTISLAND)
> >>>>> +        xe->device_uuid =
> >>>>> +xe_mmio_read64_2x32(xe_root_tile_mmio(xe), CRI_DEVICE_UUID);
> >>>>> +
> >>>>>       /*
> >>>>>        * Check for pcode uncore_init status to confirm if the SoC
> >>>>>        * initialization is complete. Until done, any MMIO or lmem
> >>>>> access from diff --git a/drivers/gpu/drm/xe/xe_device_sysfs.c
> >>>>> b/drivers/gpu/drm/xe/xe_device_sysfs.c
> >>>>> index a73e0e957cb0..a4d326159dce 100644
> >>>>> --- a/drivers/gpu/drm/xe/xe_device_sysfs.c
> >>>>> +++ b/drivers/gpu/drm/xe/xe_device_sysfs.c
> >>>>> @@ -8,6 +8,7 @@
> >>>>>   #include <linux/pci.h>
> >>>>>   #include <linux/sysfs.h>
> >>>>>   +#include "regs/xe_regs.h"
> >>>>>   #include "xe_device.h"
> >>>>>   #include "xe_device_sysfs.h"
> >>>>>   #include "xe_mmio.h"
> >>>>> @@ -264,6 +265,35 @@ static const struct attribute_group
> >>>>> auto_link_downgrade_attr_group = {
> >>>>>       .attrs = auto_link_downgrade_attrs,
> >>>>>   };
> >>>>>   +/**
> >>>>> + * DOC: device_uuid
> >>>> do we need this?
> >>>> you already described that in Documentation/ABI
> >>> I think I will drop the Documentation/ABI and keep DOC: section.
> >>
> >> hmm, but all other sysfs entries are defined in Documentation/ABI (which
> >> IMO is the correct place, not a local DOC section)
> > Is there a way to link the Documentation/ABI doc with drm/Xe Doc,  in case local doc is not preferred.
> > https://docs.kernel.org/gpu/xe/index.html
> > As this is Xe specific sysfs , AFAIU there should be some way from Xe Kernel Doc to refer this sysfs ?
>
> it should be sufficient to use:
>
> 	"See Documentation/ABI/testing/sysfs-driver-intel-xe-gpu
> 	"for a complete description of the attributes.
>
> see https://elixir.bootlin.com/linux/v7.2.2/source/Documentation/hwmon/sysfs-interface.rst#L92
> and resulting https://docs.kernel.org/hwmon/sysfs-interface.html#attribute-access

yes, please, let's simplify this as much as we can.

>
> > Thanks,
> > Anshuman
> >>
> >>
> >>>>
> >>>>> + *
> >>>>> + * Each Xe device exposes a 64-bit UUID that uniquely identifies the SoC.
> >>>>> + * The value is read from the CRI_DEVICE_UUID register and can be
> >>>>> + * read back through the ``device_uuid`` sysfs entry.
> >>>>> + *
> >>>>> + *    $ cat /sys/bus/pci/devices/<bdf>/device_uuid
> >>>>> + */
> >>>>> +
> >>>>> +static ssize_t
> >>>>> +device_uuid_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);
> >>>>> +
> >>>>> +    return sysfs_emit(buf, "%016llx\n", xe->device_uuid);
> >>>> %pU ?
> >>> Not needed.
> >>>>
> >>>>> +}
> >>>>> +static DEVICE_ATTR_RO(device_uuid);
> >>>>> +
> >>>>> +static struct attribute *device_uuid_attrs[] = {
> >>>>> +    &dev_attr_device_uuid.attr,
> >>>>> +    NULL
> >>>>> +};
> >>>>> +
> >>>>> +static const struct attribute_group device_uuid_attr_group = {
> >>>>> +    .attrs = device_uuid_attrs,
> >>>>> +};
> >>>>> +
> >>>>>   int xe_device_sysfs_init(struct xe_device *xe)
> >>>>>   {
> >>>>>       struct device *dev = xe->drm.dev; @@ -285,5 +315,11 @@ int
> >>>>> xe_device_sysfs_init(struct xe_device *xe)
> >>>>>               return ret;
> >>>>>       }
> >>>>>   +    if (xe->info.platform == XE_CRESCENTISLAND) {
> >>>> use .is_visible instead
> >>>
> >>> Will add has flag.
> >>
> >> to be clear: my point was to move this check to the
> >>
> >> 	attribute_group.is_visible
> >>
> >> and I don't care whether it will use .has_uid or .platform field
> >>
> >>
> >>>
> >>> Thanks,
> >>> Badal
> >>>
> >>>>
> >>>>> +        ret = devm_device_add_group(dev, &device_uuid_attr_group);
> >>>>> +        if (ret)
> >>>>> +            return ret;
> >>>>> +    }
> >>>>> +
> >>>>>       return 0;
> >>>>>   }
> >>>>> diff --git a/drivers/gpu/drm/xe/xe_device_types.h
> >>>>> b/drivers/gpu/drm/xe/xe_device_types.h
> >>>>> index 180d450a6deb..6fdd16eac906 100644
> >>>>> --- a/drivers/gpu/drm/xe/xe_device_types.h
> >>>>> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> >>>>> @@ -257,6 +257,9 @@ struct xe_device {
> >>>>>           bool oob_initialized;
> >>>>>       } wa_active;
> >>>>>   +    /** @device_uuid: unique 64-bit identifier read from
> >>>>> CRI_DEVICE_UUID */
> >>>>> +    u64 device_uuid;
> >>>>> +
> >>>>>       /** @survivability: survivability information for device */
> >>>>>       struct xe_survivability survivability;
> >>>>>
> >
>