Re: [PATCH v2 7/7] drm/xe/pt: unify xe_pt_svm_pre_commit with userptr

[Matthew Brost <matthew.brost@intel.com>]

On Fri, Apr 04, 2025 at 09:19:34AM +0100, Matthew Auld wrote:
> On 03/04/2025 22:25, Matthew Brost wrote:
> > On Fri, Mar 28, 2025 at 06:10:36PM +0000, Matthew Auld wrote:
> > > We now use the same notifier lock for SVM and userptr, with that we can
> > > combine xe_pt_userptr_pre_commit and xe_pt_svm_pre_commit.
> > > 
> > > Suggested-by: Matthew Brost <matthew.brost@intel.com>
> > > Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> > > Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> > > Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > > ---
> > >   drivers/gpu/drm/xe/xe_pt.c | 95 +++++++++++++-------------------------
> > >   1 file changed, 33 insertions(+), 62 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
> > > index b097c91e2e02..947b82aa19a6 100644
> > > --- a/drivers/gpu/drm/xe/xe_pt.c
> > > +++ b/drivers/gpu/drm/xe/xe_pt.c
> > > @@ -1396,7 +1396,7 @@ static int op_check_userptr(struct xe_vm *vm, struct xe_vma_op *op,
> > >   	return err;
> > >   }
> > > -static int xe_pt_userptr_pre_commit(struct xe_migrate_pt_update *pt_update)
> > > +static int xe_pt_svm_userptr_pre_commit(struct xe_migrate_pt_update *pt_update)
> > >   {
> > >   	struct xe_vm *vm = pt_update->vops->vm;
> > >   	struct xe_vma_ops *vops = pt_update->vops;
> > > @@ -1409,55 +1409,40 @@ static int xe_pt_userptr_pre_commit(struct xe_migrate_pt_update *pt_update)
> > >   	if (err)
> > >   		return err;
> > > -	down_read(&vm->svm.gpusvm.notifier_lock);
> > > +	drm_gpusvm_notifier_lock(&vm->svm.gpusvm);
> > 
> > Also any reason not use xe_svm_notifier_lock / xe_svm_notifier_unlock wrappers?
> 
> Just that those are hidden behind CONFIG_DRM_XE_GPUSVM, so looks possible to
> disable svm, but then I think we should still have working userptr. Should I
> pull xe_svm_notifier_lock out of CONFIG_DRM_XE_GPUSVM?
> 

How would userptr work without GPU SVM if we building it on top of it?

Matt

> > 
> > Matt
> > 
> > >   	list_for_each_entry(op, &vops->list, link) {
> > > -		err = op_check_userptr(vm, op, pt_update_ops);
> > > -		if (err) {
> > > -			up_read(&vm->svm.gpusvm.notifier_lock);
> > > -			break;
> > > +		if (pt_update_ops->needs_svm_lock) {
> > > +#if IS_ENABLED(CONFIG_DRM_XE_GPUSVM)
> > > +			struct xe_svm_range *range = op->map_range.range;
> > > +
> > > +			if (op->subop == XE_VMA_SUBOP_UNMAP_RANGE)
> > > +				continue;
> > > +
> > > +			xe_svm_range_debug(range, "PRE-COMMIT");
> > > +
> > > +			xe_assert(vm->xe,
> > > +				  xe_vma_is_cpu_addr_mirror(op->map_range.vma));
> > > +			xe_assert(vm->xe, op->subop == XE_VMA_SUBOP_MAP_RANGE);
> > > +
> > > +			if (!xe_svm_range_pages_valid(range)) {
> > > +				xe_svm_range_debug(range, "PRE-COMMIT - RETRY");
> > > +				drm_gpusvm_notifier_unlock(&vm->svm.gpusvm);
> > > +				return -EAGAIN;
> > > +			}
> > > +#endif
> > > +		} else {
> > > +			err = op_check_userptr(vm, op, pt_update_ops);
> > > +			if (err) {
> > > +				drm_gpusvm_notifier_unlock(&vm->svm.gpusvm);
> > > +				break;
> > > +			}
> > >   		}
> > >   	}
> > >   	return err;
> > >   }
> > > -#if IS_ENABLED(CONFIG_DRM_XE_GPUSVM)
> > > -static int xe_pt_svm_pre_commit(struct xe_migrate_pt_update *pt_update)
> > > -{
> > > -	struct xe_vm *vm = pt_update->vops->vm;
> > > -	struct xe_vma_ops *vops = pt_update->vops;
> > > -	struct xe_vma_op *op;
> > > -	int err;
> > > -
> > > -	err = xe_pt_pre_commit(pt_update);
> > > -	if (err)
> > > -		return err;
> > > -
> > > -	xe_svm_notifier_lock(vm);
> > > -
> > > -	list_for_each_entry(op, &vops->list, link) {
> > > -		struct xe_svm_range *range = op->map_range.range;
> > > -
> > > -		if (op->subop == XE_VMA_SUBOP_UNMAP_RANGE)
> > > -			continue;
> > > -
> > > -		xe_svm_range_debug(range, "PRE-COMMIT");
> > > -
> > > -		xe_assert(vm->xe, xe_vma_is_cpu_addr_mirror(op->map_range.vma));
> > > -		xe_assert(vm->xe, op->subop == XE_VMA_SUBOP_MAP_RANGE);
> > > -
> > > -		if (!xe_svm_range_pages_valid(range)) {
> > > -			xe_svm_range_debug(range, "PRE-COMMIT - RETRY");
> > > -			xe_svm_notifier_unlock(vm);
> > > -			return -EAGAIN;
> > > -		}
> > > -	}
> > > -
> > > -	return 0;
> > > -}
> > > -#endif
> > > -
> > >   struct invalidation_fence {
> > >   	struct xe_gt_tlb_invalidation_fence base;
> > >   	struct xe_gt *gt;
> > > @@ -2255,22 +2240,12 @@ static const struct xe_migrate_pt_update_ops migrate_ops = {
> > >   	.pre_commit = xe_pt_pre_commit,
> > >   };
> > > -static const struct xe_migrate_pt_update_ops userptr_migrate_ops = {
> > > +static const struct xe_migrate_pt_update_ops svm_userptr_migrate_ops = {
> > >   	.populate = xe_vm_populate_pgtable,
> > >   	.clear = xe_migrate_clear_pgtable_callback,
> > > -	.pre_commit = xe_pt_userptr_pre_commit,
> > > +	.pre_commit = xe_pt_svm_userptr_pre_commit,
> > >   };
> > > -#if IS_ENABLED(CONFIG_DRM_XE_GPUSVM)
> > > -static const struct xe_migrate_pt_update_ops svm_migrate_ops = {
> > > -	.populate = xe_vm_populate_pgtable,
> > > -	.clear = xe_migrate_clear_pgtable_callback,
> > > -	.pre_commit = xe_pt_svm_pre_commit,
> > > -};
> > > -#else
> > > -static const struct xe_migrate_pt_update_ops svm_migrate_ops;
> > > -#endif
> > > -
> > >   /**
> > >    * xe_pt_update_ops_run() - Run PT update operations
> > >    * @tile: Tile of PT update operations
> > > @@ -2296,10 +2271,8 @@ xe_pt_update_ops_run(struct xe_tile *tile, struct xe_vma_ops *vops)
> > >   	struct xe_vma_op *op;
> > >   	int err = 0, i;
> > >   	struct xe_migrate_pt_update update = {
> > > -		.ops = pt_update_ops->needs_svm_lock ?
> > > -			&svm_migrate_ops :
> > > -			pt_update_ops->needs_userptr_lock ?
> > > -			&userptr_migrate_ops :
> > > +		.ops = pt_update_ops->needs_svm_lock || pt_update_ops->needs_userptr_lock ?
> > > +			&svm_userptr_migrate_ops :
> > >   			&migrate_ops,
> > >   		.vops = vops,
> > >   		.tile_id = tile->id,
> > > @@ -2419,10 +2392,8 @@ xe_pt_update_ops_run(struct xe_tile *tile, struct xe_vma_ops *vops)
> > >   				  &ifence->base.base, &mfence->base.base);
> > >   	}
> > > -	if (pt_update_ops->needs_svm_lock)
> > > -		xe_svm_notifier_unlock(vm);
> > > -	if (pt_update_ops->needs_userptr_lock)
> > > -		up_read(&vm->svm.gpusvm.notifier_lock);
> > > +	if (pt_update_ops->needs_svm_lock || pt_update_ops->needs_userptr_lock)
> > > +		drm_gpusvm_notifier_unlock(&vm->svm.gpusvm);
> > >   	return fence;
> > > -- 
> > > 2.48.1
> > > 
>