Re: [PATCH] drm/xe: Do not allow scratch page on long running jobs

[Nirmoy Das <nirmoy.das@linux.intel.com>]

On 9/19/2024 5:52 PM, Matthew Brost wrote:
> On Thu, Sep 19, 2024 at 12:47:04PM +0200, Nirmoy Das wrote:
>> This was agreed upon but not enforced, so enforce the limitation
>> of not allowing scratch pages on long-running jobs unless absolutely
>> required, which is currently the case for a DG2 SKU.
>>
>> Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Cc: Matthew Brost <matthew.brost@intel.com>
> I think this type of change we will need a maintainer to bless and
> likely someone from the compute UMD.

Agree. Adding Michal and Rodrigo as well


>
> It does LGTM, with that:
> Acked-by: Matthew Brost <matthew.brost@intel.com>


Thanks,

Nirmoy

>
>> Cc: Stuart Summers <stuart.summers@intel.com>
>> Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
>> Suggested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>> ---
>>  drivers/gpu/drm/xe/xe_vm.c | 16 +++++++++++++++-
>>  1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
>> index a3d7cb7cfd22..92dc55f3479b 100644
>> --- a/drivers/gpu/drm/xe/xe_vm.c
>> +++ b/drivers/gpu/drm/xe/xe_vm.c
>> @@ -1711,6 +1711,11 @@ find_ufence_get(struct xe_sync_entry *syncs, u32 num_syncs)
>>  	return NULL;
>>  }
>>  
>> +static bool xe_vm_device_requires_scratch_page(struct xe_device *xe)
>> +{
>> +	return XE_WA(xe_root_mmio_gt(xe), 14016763929);
>> +}
>> +
>>  #define ALL_DRM_XE_VM_CREATE_FLAGS (DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE | \
>>  				    DRM_XE_VM_CREATE_FLAG_LR_MODE | \
>>  				    DRM_XE_VM_CREATE_FLAG_FAULT_MODE)
>> @@ -1730,7 +1735,7 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
>>  	if (XE_IOCTL_DBG(xe, args->extensions))
>>  		return -EINVAL;
>>  
>> -	if (XE_WA(xe_root_mmio_gt(xe), 14016763929))
>> +	if (xe_vm_device_requires_scratch_page(xe))
>>  		args->flags |= DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE;
>>  
>>  	if (XE_IOCTL_DBG(xe, args->flags & DRM_XE_VM_CREATE_FLAG_FAULT_MODE &&
>> @@ -1747,6 +1752,15 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
>>  			 args->flags & DRM_XE_VM_CREATE_FLAG_FAULT_MODE))
>>  		return -EINVAL;
>>  
>> +	/*
>> +	 * Scratch page is disabled for long running job unless absolutely
>> +	 * required as this can introduce hidden bugs.
>> +	 */
>> +	if (!xe_vm_device_requires_scratch_page(xe) &&
>> +	    XE_IOCTL_DBG(xe, args->flags & DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE &&
>> +			 (args->flags & DRM_XE_VM_CREATE_FLAG_LR_MODE)))
>> +		return -EINVAL;
>> +
>>  	if (XE_IOCTL_DBG(xe, !(args->flags & DRM_XE_VM_CREATE_FLAG_LR_MODE) &&
>>  			 args->flags & DRM_XE_VM_CREATE_FLAG_FAULT_MODE))
>>  		return -EINVAL;
>> -- 
>> 2.46.0
>>