RE: [PATCH] drm/xe/migrate: Support copying between sysmem and stolen

> -----Original Message-----
> From: Intel-gfx <[email protected]> On Behalf Of Maarten
> Lankhorst
> Sent: Wednesday, July 22, 2026 12:56 AM
> To: [email protected]
> Cc: [email protected]; Maarten Lankhorst <[email protected]>
> Subject: [PATCH] drm/xe/migrate: Support copying between sysmem and stolen
> 
> Stolen memory is used on integrated devices to hold the firmware framebuffer. In
> the next commit we want to copy the framebuffer to normal system memory.
> 
> This requires treating stolen memory mostly as VRAM, but without access to the
> identity mapping.
> 
> On discrete the identity mapping can be used, but we never need to copy there, so
> just prohibit identity map on stolen.
> 
> Signed-off-by: Maarten Lankhorst <[email protected]>
> ---
>  drivers/gpu/drm/xe/xe_migrate.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index 4366c41bd3254..505d105472fca 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -574,6 +574,10 @@ static u64 xe_migrate_res_sizes(struct xe_migrate *m,
> struct xe_res_cursor *cur)
> 

This  migrate_res_sizes still uses the old function instead of is_devmem.
Is it intentional ?

Else all looks good to me.
Reviewed-by: Uma Shankar <[email protected]>

Good to be checked by someone from Core KMD side as well.

>  static bool xe_migrate_allow_identity(u64 size, const struct xe_res_cursor *cur)
> {
> +	/* Stolen only used by integrated, no VRAM or identity map there */
> +	if (cur->mem_type == XE_PL_STOLEN)
> +		return false;
> +
>  	/* If the chunk is not fragmented, allow identity map. */
>  	return cur->size >= size;
>  }
> @@ -879,6 +883,14 @@ static u32 xe_migrate_ccs_copy(struct xe_migrate *m,
>  	return flush_flags;
>  }
> 
> +static bool is_devmem(u32 mem_type)
> +{
> +	if (mem_type_is_vram(mem_type) || mem_type == XE_PL_STOLEN)
> +		return true;
> +
> +	return false;
> +}
> +
>  static struct dma_fence *__xe_migrate_copy(struct xe_migrate *m,
>  					   struct xe_bo *src_bo,
>  					   struct xe_bo *dst_bo,
> @@ -899,8 +911,8 @@ static struct dma_fence *__xe_migrate_copy(struct
> xe_migrate *m,
>  	int err;
>  	bool src_is_pltt = src->mem_type == XE_PL_TT;
>  	bool dst_is_pltt = dst->mem_type == XE_PL_TT;
> -	bool src_is_vram = mem_type_is_vram(src->mem_type);
> -	bool dst_is_vram = mem_type_is_vram(dst->mem_type);
> +	bool src_is_vram = is_devmem(src->mem_type);
> +	bool dst_is_vram = is_devmem(dst->mem_type);
>  	bool type_device = src_bo->ttm.type == ttm_bo_type_device;
>  	bool needs_ccs_emit = type_device && xe_migrate_needs_ccs_emit(xe);
>  	bool copy_ccs = xe_device_has_flat_ccs(xe) && @@ -1597,7 +1609,7
> @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
>  				   struct ttm_resource *dst,
>  				   u32 clear_flags)
>  {
> -	bool clear_vram = mem_type_is_vram(dst->mem_type);
> +	bool clear_vram = is_devmem(dst->mem_type);
>  	bool clear_bo_data = XE_MIGRATE_CLEAR_FLAG_BO_DATA &
> clear_flags;
>  	bool clear_ccs = XE_MIGRATE_CLEAR_FLAG_CCS_DATA & clear_flags;
>  	struct xe_gt *gt = m->tile->primary_gt;
> --
> 2.53.0