Re: [PATCH] drm/xe/debugfs: Don't expose dgfx residencies attributes on VF

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 9/5/2025 8:22 PM, Gustavo Sousa wrote:
> Quoting Michal Wajdeczko (2025-09-05 14:36:25-03:00)
>> In addition of checking if we are running on the BATTLEMAGE,
>> we should also check for not being a VF driver, as VFs can't
>> access necessary registers, and doing so leads to:
>>
>> | .. [drm] GT0: VF is trying to read an inaccessible register 0x35b004+0x0
>> | RIP: 0010:xe_gt_sriov_vf_read32+0x5e2/0x8a0 [xe]
>> | Call Trace:
>> |  xe_mmio_read32+0x110/0x280 [xe]
>> |  read_residency_counter+0x42/0xd0 [xe]
>> |  dgfx_pkg_residencies_show+0x115/0x190 [xe]
>> | .. [drm] Package G2 counter failed to read, ret -19
>>
>> or
>>
>> | .. [drm] GT0: VF is trying to read an inaccessible register 0x35b004+0x0
>> | RIP: 0010:xe_gt_sriov_vf_read32+0x5e2/0x8a0 [xe]
>> | Call Trace:
>> |  xe_mmio_read32+0x110/0x280 [xe]
>> |  read_residency_counter+0x42/0xd0 [xe]
>> |  dgfx_pcie_link_residencies_show+0xe7/0x160 [xe]
>> | .. [drm] PCIE LINK L0 RESIDENCY counter failed to read, ret -19
>>
>> Similarly, there is no point to expose inject_csc_hw_error on VFs,
>> as HW errors support is already disabled for VFs.
>>
>> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> Cc: Soham Purkait <soham.purkait@intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Riana Tauro <riana.tauro@intel.com>
> 
> I posted a very similar patch[1] ~1 month ago.

oops

> 
> There was a spec-related question from Rodrigo, for which I could not
> find the answer.

I guess the answer in indirect - there is only small set of registers
that VFs can read directly, and above one 0x35b004 is not on this list.

Bspec: 53221

> 
> [1] https://lore.kernel.org/all/20250729-skip-residency-debugfs-for-vfs-v1-1-3c5edec08c8b@intel.com/
> 
> --
> Gustavo Sousa
> 
>> ---
>> drivers/gpu/drm/xe/xe_debugfs.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_debugfs.c b/drivers/gpu/drm/xe/xe_debugfs.c
>> index 4b71570529a6..8be8304cb05c 100644
>> --- a/drivers/gpu/drm/xe/xe_debugfs.c
>> +++ b/drivers/gpu/drm/xe/xe_debugfs.c
>> @@ -346,7 +346,7 @@ void xe_debugfs_register(struct xe_device *xe)
>>                                  ARRAY_SIZE(debugfs_list),
>>                                  root, minor);
>>
>> -        if (xe->info.platform == XE_BATTLEMAGE) {
>> +        if (xe->info.platform == XE_BATTLEMAGE && !IS_SRIOV_VF(xe)) {
>>                 drm_debugfs_create_files(debugfs_residencies,
>>                                          ARRAY_SIZE(debugfs_residencies),
>>                                          root, minor);
>> -- 
>> 2.47.1
>>