Re: [Xen-devel] [PATCH] xen: Add __GFP_DMA flag when xen_swiotlb_init gets free pages.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Apr 20, 2015 at 06:48:24PM +0800, Chen Baozi wrote:
> Make sure that xen_swiotlb_init allocates buffers that is DMA capable.
> 
> Signed-off-by: Chen Baozi <baozich@xxxxxxxxx>
> ---
>  drivers/xen/swiotlb-xen.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> index 810ad41..7345afd 100644
> --- a/drivers/xen/swiotlb-xen.c
> +++ b/drivers/xen/swiotlb-xen.c
> @@ -235,7 +235,8 @@ retry:
>  #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
>  #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
>               while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
> -                     xen_io_tlb_start = (void 
> *)__get_free_pages(__GFP_NOWARN, order);
> +                     xen_io_tlb_start = (void *)__get_free_pages(
> +                                             __GFP_NOWARN|__GFP_DMA, order);

This is not good for x86 PV guests - as the GFP_DMA pool does not really
have pages below 4GB.

Could you  make this __GFP_DMA be dependent on (!xen_pv_domain()) or such?

>                       if (xen_io_tlb_start)
>                               break;
>                       order--;
> -- 
> 2.1.4
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel