Re: [PATCH 3/6] drm/xe/migrate: fix batch buffer sizing

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

On Wed, Oct 15, 2025 at 03:19:33PM +0100, Matthew Auld wrote:
> In xe_migrate_vram() the copy can straddle page boundaries, so the len
> might look like a single page, but actually accounting for the offset
> within the page we will need to emit more than one PTE. Otherwise in
> some cases the batch buffer will be undersized leading to warnings
> later.  We already have npages so use that instead.
> 
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

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

> ---
>  drivers/gpu/drm/xe/xe_migrate.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index a4861ede6cef..6b6caeb5cdc6 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -1894,7 +1894,7 @@ static struct dma_fence *xe_migrate_vram(struct xe_migrate *m,
>  
>  	xe_assert(xe, npages * PAGE_SIZE <= MAX_PREEMPTDISABLE_TRANSFER);
>  
> -	batch_size += pte_update_cmd_size(len);
> +	batch_size += pte_update_cmd_size(npages << PAGE_SHIFT);
>  	batch_size += EMIT_COPY_DW;
>  
>  	bb = xe_bb_new(gt, batch_size, use_usm_batch);
> -- 
> 2.51.0
>