[Mesa-dev] [PATCH 1/4] intel/aubinator: Properly handle batch buffer chaining

[Kristian Høgsberg]

On Fri, Nov 18, 2016 at 11:54 AM Jason Ekstrand <jason at jlekstrand.net>
wrote:

> From: Jason Ekstrand <jason at jlekstrand.net>
>
> The original aubinator that Kristian wrote had a bug in the handling of
> MI_BATCH_BUFFER_START that propagated into the version in upstream mesa.
> In particular, it ignored the "2nd level" bit which tells you whether this
> MI_BATCH_BUFFER_START is a subroutine call (2nd level) or a goto.  Since
> the Vulkan driver uses batch chaining, this can lead to a very confusing
> interpretation of the batches.  In some cases, depending on how things are
> laid out in the virtual GTT, you can even end up with infinite loops in
> batch processing.
>
>
All four:

Reviewed-by: Kristian H. Kristensen <hoegsberg at google.com>


> Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
> ---
>  src/intel/tools/aubinator.c | 20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/src/intel/tools/aubinator.c b/src/intel/tools/aubinator.c
> index 0d4b3f9..78682c5 100644
> --- a/src/intel/tools/aubinator.c
> +++ b/src/intel/tools/aubinator.c
> @@ -790,7 +790,25 @@ parse_commands(struct gen_spec *spec, uint32_t *cmds,
> int size, int engine)
>           else
>              start = p[1];
>
> -         parse_commands(spec, gtt + start, 1 << 20, engine);
> +         if (p[0] & (1 << 22)) {
> +            /* MI_BATCH_BUFFER_START with "2nd Level Batch Buffer" set
> acts
> +             * like a subroutine call.  Commands that come afterwards get
> +             * processed once the 2nd level batch buffer returns with
> +             * MI_BATCH_BUFFER_END.
> +             */
> +            parse_commands(spec, gtt + start, gtt_end - start, engine);
> +         } else {
> +            /* MI_BATCH_BUFFER_START with "2nd Level Batch Buffer" unset
> acts
> +             * like a goto.  Nothing after it will ever get processed.  In
> +             * order to prevent the recursion from growing, we just reset
> the
> +             * loop and continue;
> +             */
> +            p = gtt + start;
> +            /* We don't know where secondaries end so use the GTT end */
> +            end = gtt + gtt_end;
> +            length = 0;
> +            continue;
> +         }
>        } else if ((p[0] & 0xffff0000) == AUB_MI_BATCH_BUFFER_END) {
>           break;
>        }
> --
> 2.5.0.400.gff86faf
>
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