Re: [PATCH 2/2] drm/xe/migrate: use XE_BO_FLAG_PAGETABLE

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

On Tue, Nov 26, 2024 at 06:13:01PM +0000, Matthew Auld wrote:
> On some HW we want to avoid the host caching PTEs, since access from GPU
> side can be incoherent. However here the special migrate object is
> mapping PTEs which are written from the host and potentially cached. Use
> XE_BO_FLAG_PAGETABLE to ensure that non-cached mapping is used, on
> platforms where this matters.
> 
> Fixes: 7a060d786cc1 ("drm/xe/mtl: Map PPGTT as CPU:WC")
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> Cc: Nirmoy Das <nirmoy.das@intel.com>
> Cc: <stable@vger.kernel.org> # v6.8+
> ---
>  drivers/gpu/drm/xe/xe_migrate.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index 48e205a40fd2..1b97d90aadda 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -209,7 +209,8 @@ static int xe_migrate_prepare_vm(struct xe_tile *tile, struct xe_migrate *m,
>  				  num_entries * XE_PAGE_SIZE,
>  				  ttm_bo_type_kernel,
>  				  XE_BO_FLAG_VRAM_IF_DGFX(tile) |
> -				  XE_BO_FLAG_PINNED);
> +				  XE_BO_FLAG_PINNED |
> +				  XE_BO_FLAG_PAGETABLE);
>  	if (IS_ERR(bo))
>  		return PTR_ERR(bo);
>  
> -- 
> 2.47.0
>