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

On 7/22/26 21:01, Shankar, Uma wrote:
> 
> 
>> -----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]>

Yeah, min_chunk_size is not set on integrated and that was causing an infinite loop
during boot.

The previous version of this patch had that issue worked around by unconditionally
setting min_chunk_size for making migrate_res_size work, but the smaller delta makes
it worth not fixing.

Thanks!

> 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
>