[Beignet] [PATCH] intel: Check that we can reserve the zero-offset

[Song, Ruiling]

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of
> Chris Wilson
> Sent: Monday, November 14, 2016 9:35 PM
> To: beignet at lists.freedesktop.org
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Subject: [Beignet] [PATCH] intel: Check that we can reserve the zero-offset
> 
> commit ff57cee0519d ("ocl20/runtime: take the first 64KB page table
> entries") tries to allocate a bo at 0 offset, but failed to take into
> account that something may already be allocated there that it is not
> allowed to evict (particularly when not using full-ppgtt separation).
> Failure to do so causes all execution to subsequentally fail with
> "drm_intel_gem_bo_context_exec() failed: Device or resource busy"
> 
> Reported-by: Kenneth Johansson <ken at kenjo.org>
> Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=98647
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  src/intel/intel_driver.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/src/intel/intel_driver.c b/src/intel/intel_driver.c
> index 363e018..a6074ae 100644
> --- a/src/intel/intel_driver.c
> +++ b/src/intel/intel_driver.c
> @@ -143,10 +143,14 @@ intel_driver_context_init(intel_driver_t *driver)
>  #ifdef HAS_BO_SET_SOFTPIN
>    drm_intel_bo *bo = dri_bo_alloc(driver->bufmgr, "null_bo", 64*1024, 4096);
>    drm_intel_bo_set_softpin_offset(bo, 0);
> -  // don't reuse it, that would make two bo trying to bind to same address,
> -  // which is un-reasonable.
> -  drm_intel_bo_disable_reuse(bo);
Please don't remove the " drm_intel_bo_disable_reuse()". when the bo is reused, the soft-pinned flag is not cleared in libdrm.
So when it is reused as an ordinary bo(not soft-pinned), it will again ask the kmd to bind it to the old zero offset which is not as expected.
> -  driver->null_bo = bo;
> +  drm_intel_bo_map(bo, true);
> +  *(uint32_t *)bo->virtual = MI_BATCH_BUFFER_END;
> +  if (drm_intel_gem_bo_context_exec(bo, driver->ctx, 0, 0) == 0) {
> +    drm_intel_bo_map(bo, true);
> +    driver->null_bo = memset(bo->virtual, 0, 64*1024);
And the null_bo should points to the 'bo', but you let it points to bo->virtual, any reason?
I notice you mapped the bo twice without unmap. Do we need unmap() here?
I am sorry for the late reply.

- Ruiling
> +  } else {
> +    drm_intel_bo_unreference(bo);
> +  }
>  #endif
>  }
> 
> --
> 2.10.2
> 
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