Re: [RFC] drm/msm: Disallow relocs on a6xx+

From: Daniel Vetter
Date: Thu Aug 03 2023 - 04:37:08 EST


On Wed, Aug 02, 2023 at 03:10:44PM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@xxxxxxxxxxxx>
>
> Mesa stopped using these pretty early in a6xx bringup. Take advantage
> of this to disallow some legacy UABI.
>
> Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
> ---
> So, it was late 2018 when mesa stopped using relocs. At that point a6xx
> support was still in a pretty early state. I guess you _could_ use such
> an old version of mesa with a6xx hw.. but you really shouldn't.

Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>

Might be good to cite the mesa commit that removed the a6xx reloc code in
the commit message.
-Sima

>
> drivers/gpu/drm/msm/adreno/adreno_gpu.c | 2 ++
> drivers/gpu/drm/msm/msm_gem_submit.c | 10 ++++++++++
> drivers/gpu/drm/msm/msm_gpu.h | 9 +++++++++
> 3 files changed, 21 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index ba35c2a87021..695cce82d914 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -1078,6 +1078,8 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
> adreno_gpu->info = config->info;
> adreno_gpu->chip_id = config->chip_id;
>
> + gpu->allow_relocs = config->info->family < ADRENO_6XX_GEN1;
> +
> /* Only handle the core clock when GMU is not in use (or is absent). */
> if (adreno_has_gmu_wrapper(adreno_gpu) ||
> adreno_gpu->info->family < ADRENO_6XX_GEN1) {
> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> index 63c96416e183..3b908f9f5493 100644
> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> @@ -882,6 +882,16 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
> if (submit->valid)
> continue;
>
> + if (!gpu->allow_relocs) {
> + if (submit->cmd[i].nr_relocs) {
> + DRM_ERROR("relocs not allowed\n");
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + continue;
> + }
> +
> ret = submit_reloc(submit, msm_obj, submit->cmd[i].offset * 4,
> submit->cmd[i].nr_relocs, submit->cmd[i].relocs);
> if (ret)
> diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> index 7a4fa1b8655b..4252e3839fbc 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.h
> +++ b/drivers/gpu/drm/msm/msm_gpu.h
> @@ -285,6 +285,15 @@ struct msm_gpu {
> /* True if the hardware supports expanded apriv (a650 and newer) */
> bool hw_apriv;
>
> + /**
> + * @allow_relocs: allow relocs in SUBMIT ioctl
> + *
> + * Mesa won't use relocs for driver version 1.4.0 and later. This
> + * switch-over happened early enough in mesa a6xx bringup that we
> + * can disallow relocs for a6xx and newer.
> + */
> + bool allow_relocs;
> +
> struct thermal_cooling_device *cooling;
> };
>
> --
> 2.41.0
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch