[PATCH] drm/panfrost: Implement per FD address spaces

[Matthew Auld]

On Thu, 8 Aug 2019 at 23:29, Rob Herring <robh at kernel.org> wrote:
>
> Up until now, a single shared GPU address space was used. This is not
> ideal as there's no protection between processes and doesn't work for
> supporting the same GPU/CPU VA feature. Most importantly, this will
> hopefully mitigate Alyssa's fear of WebGL, whatever that is.
>
> Most of the changes here are moving struct drm_mm and struct
> panfrost_mmu objects from the per device struct to the per FD struct.
> The critical function is panfrost_mmu_as_get() which handles allocating
> and switching the h/w address spaces.
>
> Cc: Tomeu Vizoso <tomeu.vizoso at collabora.com>
> Cc: David Airlie <airlied at linux.ie>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: Robin Murphy <robin.murphy at arm.com>
> Cc: Steven Price <steven.price at arm.com>
> Cc: Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
> Signed-off-by: Rob Herring <robh at kernel.org>
> ---
> This depends on madvise support (now in drm-misc) and the heap/no-exec
> series (just the rework). Seeems to be working pretty well for me, but
> more testing would be helpful. I've run multiple 'glmark2-es2-drm
> --off-screen' instances and Gnome Shell. Running more than 8 clients (at
> least for T860) will hit the address space switch code paths.
>
> Rob
>
>  drivers/gpu/drm/panfrost/TODO              |   4 -
>  drivers/gpu/drm/panfrost/panfrost_device.c |   2 +
>  drivers/gpu/drm/panfrost/panfrost_device.h |  24 ++-
>  drivers/gpu/drm/panfrost/panfrost_drv.c    |  31 ++-
>  drivers/gpu/drm/panfrost/panfrost_gem.c    |  15 +-
>  drivers/gpu/drm/panfrost/panfrost_gem.h    |   3 +
>  drivers/gpu/drm/panfrost/panfrost_job.c    |  12 +-
>  drivers/gpu/drm/panfrost/panfrost_mmu.c    | 220 +++++++++++++++------
>  drivers/gpu/drm/panfrost/panfrost_mmu.h    |   8 +
>  9 files changed, 239 insertions(+), 80 deletions(-)

[snip]

> @@ -413,7 +414,28 @@ panfrost_open(struct drm_device *dev, struct drm_file *file)
>         panfrost_priv->pfdev = pfdev;
>         file->driver_priv = panfrost_priv;
>
> -       return panfrost_job_open(panfrost_priv);
> +       spin_lock_init(&panfrost_priv->mm_lock);
> +
> +       /* 4G enough for now. can be 48-bit */
> +       panfrost_priv->mm.color_adjust = panfrost_drm_mm_color_adjust;
> +       drm_mm_init(&panfrost_priv->mm, SZ_32M >> PAGE_SHIFT, (SZ_4G - SZ_32M) >> PAGE_SHIFT);

Drive-by-comment: drm_mm_init will trample your color_adjust. Intentional?