[PATCH v1 3/4] drm/xe: Force user context allocations in user VRAM

[Matthew Auld]

On 18/07/2025 09:17, Piórkowski, Piotr wrote:
> From: Piotr Piórkowski <piotr.piorkowski at intel.com>
> 
> In general, kernel structures should be allocated in the kernel-dedicated
> VRAM region. However, userspace context data - while used by the kernel -
> does not need to reside there.
> Let's force the allocation of such data in the general-purpose VRAM region
> accessible to userspace.
> 
> Signed-off-by: Piotr Piórkowski <piotr.piorkowski at intel.com>
> ---
>   drivers/gpu/drm/xe/xe_exec_queue.c | 7 +++++--
>   drivers/gpu/drm/xe/xe_lrc.c        | 3 +++
>   drivers/gpu/drm/xe/xe_lrc.h        | 5 +++--
>   drivers/gpu/drm/xe/xe_pt.c         | 2 +-
>   4 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c b/drivers/gpu/drm/xe/xe_exec_queue.c
> index 8991b4aed440..abd29191186e 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -112,7 +112,7 @@ static struct xe_exec_queue *__xe_exec_queue_alloc(struct xe_device *xe,
>   	return q;
>   }
>   
> -static int __xe_exec_queue_init(struct xe_exec_queue *q)
> +static int __xe_exec_queue_init(struct xe_exec_queue *q, u32 exec_queue_flags)
>   {
>   	int i, err;
>   	u32 flags = 0;
> @@ -131,6 +131,9 @@ static int __xe_exec_queue_init(struct xe_exec_queue *q)
>   			flags |= XE_LRC_CREATE_RUNALONE;
>   	}
>   
> +	if (!(exec_queue_flags & EXEC_QUEUE_FLAG_KERNEL))
> +		flags |= XE_LRC_CREATE_USER_CTX;
> +
>   	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])) {
> @@ -167,7 +170,7 @@ struct xe_exec_queue *xe_exec_queue_create(struct xe_device *xe, struct xe_vm *v
>   	if (IS_ERR(q))
>   		return q;
>   
> -	err = __xe_exec_queue_init(q);
> +	err = __xe_exec_queue_init(q, flags);
>   	if (err)
>   		goto err_post_alloc;
>   
> diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
> index 6d38411bdeba..ed53f8e2448b 100644
> --- a/drivers/gpu/drm/xe/xe_lrc.c
> +++ b/drivers/gpu/drm/xe/xe_lrc.c
> @@ -1203,6 +1203,9 @@ static int xe_lrc_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe,
>   	if (vm && vm->xef) /* userspace */
>   		bo_flags |= XE_BO_FLAG_PINNED_LATE_RESTORE;
>   
> +	if (init_flags & XE_LRC_CREATE_USER_CTX)
> +		bo_flags |= XE_BO_FLAG_FORCE_USER_VRAM;

We can't use the xef check above?

> +
>   	lrc->bo = xe_bo_create_pin_map(xe, tile, NULL, bo_size,
>   				       ttm_bo_type_kernel,
>   				       bo_flags);
> diff --git a/drivers/gpu/drm/xe/xe_lrc.h b/drivers/gpu/drm/xe/xe_lrc.h
> index b6c8053c581b..57f661aa9b1c 100644
> --- a/drivers/gpu/drm/xe/xe_lrc.h
> +++ b/drivers/gpu/drm/xe/xe_lrc.h
> @@ -42,8 +42,9 @@ struct xe_lrc_snapshot {
>   #define LRC_PPHWSP_FLUSH_INVAL_SCRATCH_ADDR (0x34 * 4)
>   #define LRC_PPHWSP_PXP_INVAL_SCRATCH_ADDR (0x40 * 4)
>   
> -#define XE_LRC_CREATE_RUNALONE 0x1
> -#define XE_LRC_CREATE_PXP 0x2
> +#define XE_LRC_CREATE_RUNALONE		BIT(0)
> +#define XE_LRC_CREATE_PXP		BIT(1)
> +#define XE_LRC_CREATE_USER_CTX		BIT(2)
>   struct xe_lrc *xe_lrc_create(struct xe_hw_engine *hwe, struct xe_vm *vm,
>   			     u32 ring_size, u16 msix_vec, u32 flags);
>   void xe_lrc_destroy(struct kref *ref);
> diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
> index c8e63bd23300..a6c5f810c815 100644
> --- a/drivers/gpu/drm/xe/xe_pt.c
> +++ b/drivers/gpu/drm/xe/xe_pt.c
> @@ -120,7 +120,7 @@ struct xe_pt *xe_pt_create(struct xe_vm *vm, struct xe_tile *tile,
>   		   XE_BO_FLAG_IGNORE_MIN_PAGE_SIZE |
>   		   XE_BO_FLAG_NO_RESV_EVICT | XE_BO_FLAG_PAGETABLE;
>   	if (vm->xef) /* userspace */
> -		bo_flags |= XE_BO_FLAG_PINNED_LATE_RESTORE;
> +		bo_flags |= XE_BO_FLAG_PINNED_LATE_RESTORE | XE_BO_FLAG_FORCE_USER_VRAM;
>   
>   	pt->level = level;
>   	bo = xe_bo_create_pin_map(vm->xe, tile, vm, SZ_4K,