[Mesa-dev] [PATCH] radv: Invalidate L2 for TRANSFER_WRITE barriers

[Bas Nieuwenhuizen]

On Tue, Mar 21, 2017 at 1:02 PM, Alex Smith <asmith at feralinteractive.com> wrote:
> CP DMA and PKT3_WRITE_DATA (in CmdUpdateBuffer) don't (currently) write
> through L2. Therefore, to make these writes visible to later accesses
> we must invalidate L2 rather than just writing it back, to avoid the
> possibility that stale data is read through L2.
>
> Cc: "17.0" <mesa-stable at lists.freedesktop.org>
> Signed-off-by: Alex Smith <asmith at feralinteractive.com>
> ---
> It's possible for both CP DMA and PKT3_WRITE_DATA to write through L2
> as far as I can see, and changing things so that they do also solves
> the problems that this patch fixes.
>
> However, I don't know what the exact consequences of doing so are, or
> whether there are any situations where that shouldn't be done, so I've
> gone with this fix instead as it seems like a safer option for now.

Yeah we should be able to. I'm more comfortable sending this patch to
stable though, so this patch is

Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>


> ---
>  src/amd/vulkan/radv_cmd_buffer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
> index ba192f3..d3397a0 100644
> --- a/src/amd/vulkan/radv_cmd_buffer.c
> +++ b/src/amd/vulkan/radv_cmd_buffer.c
> @@ -1477,7 +1477,7 @@ radv_src_access_flush(struct radv_cmd_buffer *cmd_buffer,
>                                       RADV_CMD_FLAG_FLUSH_AND_INV_CB_META |
>                                       RADV_CMD_FLAG_FLUSH_AND_INV_DB |
>                                       RADV_CMD_FLAG_FLUSH_AND_INV_DB_META |
> -                                     RADV_CMD_FLAG_WRITEBACK_GLOBAL_L2;
> +                                     RADV_CMD_FLAG_INV_GLOBAL_L2;
>                         break;
>                 default:
>                         break;
> --
> 2.9.3
>