[Intel-gfx] [PATCH i-g-t v5] lib/igt_gt: Allow non-default contexts to hang non-render rings

[Chris Wilson]

Quoting Vinay Belgaumkar (2017-10-12 17:47:10)
> This limitation does not exist in latest kernel. It was removed by this patch-
> 
> commit f7978a0c581a8a840a28306f8da43e06e7fef3bf
> 
> v2: Added commit id that removes the limitation(Chris Wilson)
> V3: Generic way to find if kernel supports this instead of hardcoding gens(Chris Wilson)
> v4: Optimize the if block (Daniele)
> v5: Use the same context instead of creating a dummy (Chris Wilson)
> 
> Cc: Michel Thierry <michel.thierry at intel.com>
> Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
> Cc: Petri Latvala <petri.latvala at intel.com>
> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> ---
>  lib/igt_gt.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 42 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/igt_gt.c b/lib/igt_gt.c
> index b3f3b38..2c88de6 100644
> --- a/lib/igt_gt.c
> +++ b/lib/igt_gt.c
> @@ -209,11 +209,51 @@ void igt_disallow_hang(int fd, igt_hang_t arg)
>  }
>  
>  /**
> + * has_ctx_exec:
> + * @fd: open i915 drm file descriptor
> + * @ring: execbuf ring flag
> + * @ctx: Context to be checked
> + *
> + * This helper function checks if non default context submission is allowed
> + * on a ring.
> + *
> + * Returns:
> + * True if allowed
> + *
> + */
> +static bool has_ctx_exec(int fd, unsigned ring, uint32_t ctx)
> +{
> +       struct drm_i915_gem_execbuffer2 execbuf;
> +       struct drm_i915_gem_exec_object2 exec;
> +       bool supported;
> +
> +       /* silly ABI, the kernel thinks everyone who has BSD also has BSD2 */
> +       if ((ring & ~(3<<13)) == I915_EXEC_BSD) {
> +               if (ring & (3 << 13) && !gem_has_bsd2(fd))
> +                       return false;
> +       }
> +
> +       memset(&exec, 0, sizeof(exec));
> +       memset(&execbuf, 0, sizeof(execbuf));
> +       execbuf.buffers_ptr = to_user_pointer(&exec);
> +       execbuf.buffer_count = 1;
> +       execbuf.flags = ring;
> +       execbuf.rsvd1 = ctx;
> +       /* If context submission is not allowed, this will return EINVAL
> +        * Otherwise, this will return ENOENT on account of no gem obj
> +        * being submitted */

/*
 * Opening and closing should on separate lines for block comments.
 */

Although we are lax on the opening /* being on a separate line, our
coding style, borrowed from the kernel, prefers to have them separate.

> +       supported = __gem_execbuf(fd, &execbuf) == -ENOENT;
> +
> +       return supported;

We can kill the local variable now.

> +}
> +
> +/**
>   * igt_hang_ring_ctx:
>   * @fd: open i915 drm file descriptor
>   * @ctx: the contxt specifier
>   * @ring: execbuf ring flag
>   * @flags: set of flags to control execution
> + * @offset: The resultant gtt offset of the exec obj
>   *
>   * This helper function injects a hanging batch associated with @ctx into @ring.
>   * It returns a #igt_hang_t structure which must be passed to
> @@ -239,8 +279,8 @@ igt_hang_t igt_hang_ctx(int fd,
>  
>         igt_require_hang_ring(fd, ring);
>  
> -       /* One day the kernel ABI will be fixed! */
> -       igt_require(ctx == 0 || ring == I915_EXEC_RENDER);
> +       /* check if non-default ctx submission is allowed */
> +       igt_require(ctx == 0 || (has_ctx_exec(fd, ring, ctx)));

Excess (brackets).

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris