Re: [PATCH V6 3/4] drm/xe/xe3p_lpg: Restrict UAPI to enable L2 flush optimization

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Thu, 2026-03-05 at 17:49 +0530, Tejas Upadhyay wrote:
> When set, starting xe3p_lpg, the L2 flush optimization
> feature will control whether L2 is in Persistent or
> Transient mode through monitoring of media activity.
> 
> To enable L2 flush optimization include new feature flag
> GUC_CTL_ENABLE_L2FLUSH_OPT for Novalake platforms when
> media type is detected.
> 
> Tighten UAPI validation to restrict userptr, svm and
> dmabuf mappings to be either 2WAY or XA+1WAY
> 
> V5(Thomas): logic correction
> V4(MattA): Modify uapi doc and commit
> V3(MattA): check valid op and pat_index value
> V2(MattA): validate dma-buf bos and madvise pat-index
> 
> Acked-by: José Roberto de Souza <jose.souza@intel.com>
> Acked-by: Michal Mrozek <michal.mrozek@intel.com>
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>

Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

> ---
>  drivers/gpu/drm/xe/xe_guc.c        |  3 +++
>  drivers/gpu/drm/xe/xe_guc_fwif.h   |  1 +
>  drivers/gpu/drm/xe/xe_vm.c         |  8 ++++++++
>  drivers/gpu/drm/xe/xe_vm_madvise.c | 23 +++++++++++++++++++++++
>  include/uapi/drm/xe_drm.h          |  4 +++-
>  5 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc.c
> b/drivers/gpu/drm/xe/xe_guc.c
> index 54d2fc780127..43dc4353206f 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -98,6 +98,9 @@ static u32 guc_ctl_feature_flags(struct xe_guc
> *guc)
>  	if (xe_guc_using_main_gamctrl_queues(guc))
>  		flags |= GUC_CTL_MAIN_GAMCTRL_QUEUES;
>  
> +	if (GRAPHICS_VER(xe) >= 35 && !IS_DGFX(xe) &&
> xe_gt_is_media_type(guc_to_gt(guc)))
> +		flags |= GUC_CTL_ENABLE_L2FLUSH_OPT;
> +
>  	return flags;
>  }
>  
> diff --git a/drivers/gpu/drm/xe/xe_guc_fwif.h
> b/drivers/gpu/drm/xe/xe_guc_fwif.h
> index bb8f71d38611..b73fae063fac 100644
> --- a/drivers/gpu/drm/xe/xe_guc_fwif.h
> +++ b/drivers/gpu/drm/xe/xe_guc_fwif.h
> @@ -67,6 +67,7 @@ struct guc_update_exec_queue_policy {
>  #define   GUC_CTL_ENABLE_PSMI_LOGGING	BIT(7)
>  #define   GUC_CTL_MAIN_GAMCTRL_QUEUES	BIT(9)
>  #define   GUC_CTL_DISABLE_SCHEDULER	BIT(14)
> +#define   GUC_CTL_ENABLE_L2FLUSH_OPT	BIT(15)
>  
>  #define GUC_CTL_DEBUG			3
>  #define   GUC_LOG_VERBOSITY		REG_GENMASK(1, 0)
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index da0ce0b3704c..0b236e08c158 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -3481,6 +3481,10 @@ static int vm_bind_ioctl_check_args(struct
> xe_device *xe, struct xe_vm *vm,
>  				 op ==
> DRM_XE_VM_BIND_OP_MAP_USERPTR) ||
>  		    XE_IOCTL_DBG(xe, coh_mode == XE_COH_NONE &&
>  				 op ==
> DRM_XE_VM_BIND_OP_MAP_USERPTR) ||
> +		    XE_IOCTL_DBG(xe,
> xe_device_is_l2_flush_optimized(xe) &&
> +				 (op ==
> DRM_XE_VM_BIND_OP_MAP_USERPTR ||
> +				  is_cpu_addr_mirror) &&
> +				 (pat_index != 19 && coh_mode !=
> XE_COH_2WAY)) ||
>  		    XE_IOCTL_DBG(xe, comp_en &&
>  				 op ==
> DRM_XE_VM_BIND_OP_MAP_USERPTR) ||
>  		    XE_IOCTL_DBG(xe, op ==
> DRM_XE_VM_BIND_OP_MAP_USERPTR &&
> @@ -3615,6 +3619,10 @@ static int xe_vm_bind_ioctl_validate_bo(struct
> xe_device *xe, struct xe_bo *bo,
>  	if (XE_IOCTL_DBG(xe, bo->ttm.base.import_attach && comp_en))
>  		return -EINVAL;
>  
> +	if (XE_IOCTL_DBG(xe, bo->ttm.base.import_attach &&
> xe_device_is_l2_flush_optimized(xe) &&
> +			 (pat_index != 19 && coh_mode !=
> XE_COH_2WAY)))
> +		return -EINVAL;
> +
>  	/* If a BO is protected it can only be mapped if the key is
> still valid */
>  	if ((bind_flags & DRM_XE_VM_BIND_FLAG_CHECK_PXP) &&
> xe_bo_is_protected(bo) &&
>  	    op != DRM_XE_VM_BIND_OP_UNMAP && op !=
> DRM_XE_VM_BIND_OP_UNMAP_ALL)
> diff --git a/drivers/gpu/drm/xe/xe_vm_madvise.c
> b/drivers/gpu/drm/xe/xe_vm_madvise.c
> index 07169586e35f..376c014239ee 100644
> --- a/drivers/gpu/drm/xe/xe_vm_madvise.c
> +++ b/drivers/gpu/drm/xe/xe_vm_madvise.c
> @@ -411,6 +411,7 @@ int xe_vm_madvise_ioctl(struct drm_device *dev,
> void *data, struct drm_file *fil
>  	struct xe_vmas_in_madvise_range madvise_range = {.addr =
> args->start,
>  							 .range = 
> args->range, };
>  	struct xe_madvise_details details;
> +	u16 pat_index, coh_mode;
>  	struct xe_vm *vm;
>  	struct drm_exec exec;
>  	int err, attr_type;
> @@ -447,6 +448,17 @@ int xe_vm_madvise_ioctl(struct drm_device *dev,
> void *data, struct drm_file *fil
>  	if (err || !madvise_range.num_vmas)
>  		goto madv_fini;
>  
> +	if (args->type == DRM_XE_MEM_RANGE_ATTR_PAT) {
> +		pat_index = array_index_nospec(args->pat_index.val,
> xe->pat.n_entries);
> +		coh_mode = xe_pat_index_get_coh_mode(xe, pat_index);
> +		if (XE_IOCTL_DBG(xe,
> madvise_range.has_svm_userptr_vmas &&
> +				 xe_device_is_l2_flush_optimized(xe)
> &&
> +				 (pat_index != 19 && coh_mode !=
> XE_COH_2WAY))) {
> +			err = -EINVAL;
> +			goto madv_fini;
> +		}
> +	}
> +
>  	if (madvise_range.has_bo_vmas) {
>  		if (args->type == DRM_XE_MEM_RANGE_ATTR_ATOMIC) {
>  			if (!check_bo_args_are_sane(vm,
> madvise_range.vmas,
> @@ -464,6 +476,17 @@ int xe_vm_madvise_ioctl(struct drm_device *dev,
> void *data, struct drm_file *fil
>  
>  				if (!bo)
>  					continue;
> +
> +				if (args->type ==
> DRM_XE_MEM_RANGE_ATTR_PAT) {
> +					if (XE_IOCTL_DBG(xe, bo-
> >ttm.base.import_attach &&
> +							
> xe_device_is_l2_flush_optimized(xe) &&
> +							 (pat_index
> != 19 &&
> +							  coh_mode
> != XE_COH_2WAY))) {
> +						err = -EINVAL;
> +						goto err_fini;
> +					}
> +				}
> +
>  				err = drm_exec_lock_obj(&exec, &bo-
> >ttm.base);
>  				drm_exec_retry_on_contention(&exec);
>  				if (err)
> diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> index ef2565048bdf..862fed3cf1ed 100644
> --- a/include/uapi/drm/xe_drm.h
> +++ b/include/uapi/drm/xe_drm.h
> @@ -1103,7 +1103,9 @@ struct drm_xe_vm_bind_op {
>  	 * incoherent GT access is possible.
>  	 *
>  	 * Note: For userptr and externally imported dma-buf the
> kernel expects
> -	 * either 1WAY or 2WAY for the @pat_index.
> +	 * either 1WAY or 2WAY for the @pat_index. Starting from
> NVL-P, for
> +	 * userptr, svm, madvise and externally imported dma-buf the
> kernel expects
> +	 * either 2WAY or 1WAY and XA @pat_index.
>  	 *
>  	 * For DRM_XE_VM_BIND_FLAG_NULL bindings there are no KMD
> restrictions
>  	 * on the @pat_index. For such mappings there is no actual
> memory being