[PATCH] drm/xe: Create LRC BO without VM
Matthew Brost
matthew.brost at intel.com
Thu May 29 04:18:21 UTC 2025
On Wed, May 28, 2025 at 09:04:49PM -0700, Niranjana Vishwanathapura wrote:
> Specifying VM during lrc->bo creation requires VM's reference
> to be held for the lifetime of lrc->bo as it will use VM's dma
> reservation object. Using VM's dma reservation object for
> lrc->bo doesn't provide any advantage. Hence do not pass VM
> while creating lrc->bo.
>
> Fixes: 264eecdba211 ("drm/xe: Decouple xe_exec_queue and xe_lrc")
> Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
Good cleanup. I thought this through and can't reason why this would
work or any advantages of the LRC using VM's dma-resv.
One nit, xe_lrc_finish can use xe_bo_unpin_map_no_vm on lrc->bo now.
Asssuming CI passes and the above nit fixed:
Reviewed-by: Matthew Brost <matthew.brost at intel.com>
> ---
> drivers/gpu/drm/xe/xe_exec_queue.c | 9 ---------
> drivers/gpu/drm/xe/xe_lrc.c | 18 +++---------------
> 2 files changed, 3 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
> index ce78cee5dec6..32c6923df7c3 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -132,12 +132,6 @@ static int __xe_exec_queue_init(struct xe_exec_queue *q)
> flags |= XE_LRC_CREATE_RUNALONE;
> }
>
> - if (vm) {
> - err = xe_vm_lock(vm, true);
> - if (err)
> - return err;
> - }
> -
> for (i = 0; i < q->width; ++i) {
> q->lrc[i] = xe_lrc_create(q->hwe, q->vm, SZ_16K, q->msix_vec, flags);
> if (IS_ERR(q->lrc[i])) {
> @@ -146,9 +140,6 @@ static int __xe_exec_queue_init(struct xe_exec_queue *q)
> }
> }
>
> - if (vm)
> - xe_vm_unlock(vm);
> -
> err = q->ops->init(q);
> if (err)
> goto err_lrc;
> diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
> index 61a2e87990a9..974fe509df0e 100644
> --- a/drivers/gpu/drm/xe/xe_lrc.c
> +++ b/drivers/gpu/drm/xe/xe_lrc.c
> @@ -1007,7 +1007,7 @@ static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
> * FIXME: Perma-pinning LRC as we don't yet support moving GGTT address
> * via VM bind calls.
> */
> - lrc->bo = xe_bo_create_pin_map(xe, tile, vm, lrc_size,
> + lrc->bo = xe_bo_create_pin_map(xe, tile, NULL, lrc_size,
> ttm_bo_type_kernel,
> bo_flags);
> if (IS_ERR(lrc->bo))
> @@ -1795,9 +1795,6 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
> if (!snapshot)
> return NULL;
>
> - if (lrc->bo->vm)
> - xe_vm_get(lrc->bo->vm);
> -
> snapshot->context_desc = xe_lrc_ggtt_addr(lrc);
> snapshot->ring_addr = __xe_lrc_ring_ggtt_addr(lrc);
> snapshot->indirect_context_desc = xe_lrc_indirect_ring_ggtt_addr(lrc);
> @@ -1819,14 +1816,12 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
> void xe_lrc_snapshot_capture_delayed(struct xe_lrc_snapshot *snapshot)
> {
> struct xe_bo *bo;
> - struct xe_vm *vm;
> struct iosys_map src;
>
> if (!snapshot)
> return;
>
> bo = snapshot->lrc_bo;
> - vm = bo->vm;
> snapshot->lrc_bo = NULL;
>
> snapshot->lrc_snapshot = kvmalloc(snapshot->lrc_size, GFP_KERNEL);
> @@ -1846,8 +1841,6 @@ void xe_lrc_snapshot_capture_delayed(struct xe_lrc_snapshot *snapshot)
> xe_bo_unlock(bo);
> put_bo:
> xe_bo_put(bo);
> - if (vm)
> - xe_vm_put(vm);
> }
>
> void xe_lrc_snapshot_print(struct xe_lrc_snapshot *snapshot, struct drm_printer *p)
> @@ -1900,14 +1893,9 @@ void xe_lrc_snapshot_free(struct xe_lrc_snapshot *snapshot)
> return;
>
> kvfree(snapshot->lrc_snapshot);
> - if (snapshot->lrc_bo) {
> - struct xe_vm *vm;
> -
> - vm = snapshot->lrc_bo->vm;
> + if (snapshot->lrc_bo)
> xe_bo_put(snapshot->lrc_bo);
> - if (vm)
> - xe_vm_put(vm);
> - }
> +
> kfree(snapshot);
> }
>
> --
> 2.43.0
>
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