[PATCH 2/3] drm/xe/pf: Invalidate LMTT during LMEM unprovisioning

[Michal Wajdeczko]

On 03.07.2025 19:31, Matthew Brost wrote:
> On Thu, Jul 03, 2025 at 12:30:40AM +0200, Michal Wajdeczko wrote:
>> Invalidate LMTT immediately after removing VF's LMTT page tables
>> and clearing root PTE in the LMTT PD to avoid any invalid access
>> by the hardware (and VF) due to stale data.
>>
>> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>> Cc: Michał Winiarski <michal.winiarski at intel.com>
>> Cc: Piotr Piórkowski <piotr.piorkowski at intel.com>
>> ---
>>  drivers/gpu/drm/xe/xe_device.h              |  4 ++
>>  drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c | 35 +++++++++++++
>>  drivers/gpu/drm/xe/xe_gt_tlb_invalidation.h |  2 +
>>  drivers/gpu/drm/xe/xe_lmtt.c                | 56 +++++++++++++++++++++
>>  drivers/gpu/drm/xe/xe_lmtt.h                |  1 +
>>  5 files changed, 98 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
>> index e4da797a984b..a7acd899aa76 100644
>> --- a/drivers/gpu/drm/xe/xe_device.h
>> +++ b/drivers/gpu/drm/xe/xe_device.h
>> @@ -130,6 +130,10 @@ static inline bool xe_device_uc_enabled(struct xe_device *xe)
>>  	for ((id__) = 1; (id__) < (xe__)->info.tile_count; (id__)++) \
>>  		for_each_if((tile__) = &(xe__)->tiles[(id__)])
>>  
>> +#define for_each_gt_on_tile(gt__, tile__, id__) \
>> +	for ((id__) = 0; (id__) < XE_MAX_GT_PER_TILE; (id__)++) \
>> +		for_each_if((gt__) = xe_tile_get_gt((tile__), (id__)))
>> +
>>  /*
>>   * FIXME: This only works for now since multi-tile and standalone media
>>   * happen to be mutually exclusive.  Future platforms may change this...
>> diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
>> index 6088df8e159c..4fdd5b300265 100644
>> --- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
>> +++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
>> @@ -330,6 +330,41 @@ int xe_gt_tlb_invalidation_ggtt(struct xe_gt *gt)
>>  	return 0;
>>  }
>>  
>> +static int send_tlb_invalidation_all(struct xe_gt *gt,
>> +				     struct xe_gt_tlb_invalidation_fence *fence)
>> +{
>> +	u32 action[] = {
>> +		XE_GUC_ACTION_TLB_INVALIDATION_ALL,
>> +		0,  /* seqno, replaced in send_tlb_invalidation */
>> +		MAKE_INVAL_OP(XE_GUC_TLB_INVAL_FULL),
>> +	};
>> +
>> +	return send_tlb_invalidation(&gt->uc.guc, fence, action, ARRAY_SIZE(action));
>> +}
>> +
>> +/**
>> + * xe_gt_tlb_invalidation_all_async - Invalidate all TLBs across PF and all VFs.
>> + * @gt: the &xe_gt structure
>> + * @fence: the &xe_gt_tlb_invalidation_fence to be signaled on completion
>> + *
>> + * Send a request to invalidate all TLBs across PF and all VFs.
>> + *
>> + * Return: 0 on success, negative error code on error
>> + */
>> +int xe_gt_tlb_invalidation_all_async(struct xe_gt *gt,
>> +				     struct xe_gt_tlb_invalidation_fence *fence)
> 
> I'd drop _async part of the naming as I think it is implied with the
> fence argument that is this async, like xe_gt_tlb_invalidation_range.

this suffix is here because initially I was also having this variant:

	int xe_gt_tlb_invalidation_all(struct xe_gt *gt);

which actually was waiting for the TLB fence inside - like it is done in
the xe_gt_tlb_invalidation_ggtt() - but finally dropped it from this
patch as not used in current code

> 
> All the changes around GT TLB invalidations look correct (for now, this
> whole layer needs rework).

yes, please ;)

> 
> Matt 
>