drm/panfrost: Implement per FD address spaces

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.

There's 3 states an AS can be in: free, allocated, and in use. When a
job runs, it requests an address space and then marks it not in use when
job is complete(but stays assigned). The first time thru, we find a free
AS in the alloc_mask and assign the AS to the FD. Then the next time
thru, we most likely already have our AS and we just mark it in use with
a ref count. We need a ref count because we have multiple job slots. If
the job/FD doesn't have an AS assigned and there are no free ones, then
we pick an allocated one not in use from our LRU list and switch the AS
from the old FD to the new one.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813150115.30338-1-robh@kernel.org

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.h b/drivers/gpu/drm/panfrost/panfrost_mmu.h
index d5f9b24537db..7c5b6775ae23 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.h
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.h
@@ -5,6 +5,8 @@
 #define __PANFROST_MMU_H__
 
 struct panfrost_gem_object;
+struct panfrost_file_priv;
+struct panfrost_mmu;
 
 int panfrost_mmu_map(struct panfrost_gem_object *bo);
 void panfrost_mmu_unmap(struct panfrost_gem_object *bo);
@@ -13,4 +15,10 @@ int panfrost_mmu_init(struct panfrost_device *pfdev);
 void panfrost_mmu_fini(struct panfrost_device *pfdev);
 void panfrost_mmu_reset(struct panfrost_device *pfdev);
 
+u32 panfrost_mmu_as_get(struct panfrost_device *pfdev, struct panfrost_mmu *mmu);
+void panfrost_mmu_as_put(struct panfrost_device *pfdev, struct panfrost_mmu *mmu);
+
+int panfrost_mmu_pgtable_alloc(struct panfrost_file_priv *priv);
+void panfrost_mmu_pgtable_free(struct panfrost_file_priv *priv);
+
 #endif