[PATCH v4 0/7] dma-buf: heaps: Add restricted heap

Yong Wu
2024-01-12T09:31:08Z

The purpose of this patchset is for MediaTek secure video playback, and
also to enable other potential uses of this in the future. The 'restricted
dma-heap' will be used to allocate dma_buf objects that reference memory
in the secure world that is inaccessible/unmappable by the non-secure
(i.e. kernel/userspace) world. That memory will be used by the secure/
trusted world to store secure information (i.e. decrypted media content).
The dma_bufs allocated from the kernel will be passed to V4L2 for video
decoding (as input and output). They will also be used by the drm
system for rendering of the content.

This patchset adds two MediaTek restricted heaps and they will be used in
v4l2[1] and drm[2].
1) restricted_mtk_cm: secure chunk memory for MediaTek SVP (Secure Video
Path). The buffer is reserved for the secure world after bootup and it
is used for vcodec's ES/working buffer;
2) restricted_mtk_cma: secure CMA memory for MediaTek SVP. This buffer is
dynamically reserved for the secure world and will be got when we start
playing secure videos. Once the security video playing is complete, the
CMA will be released. This heap is used for the vcodec's frame buffer.

[1] https://lore.kernel.org/linux-mediatek/20231206081538.17056-1-yunfei.dong@mediatek.com/
[2] https://lore.kernel.org/all/20231223182932.27683-1-jason-jh.lin@mediatek.com/

Change note:
v4: 1) Rename the heap name from "secure" to "restricted". suggested from
Simon/Pekka. There are still several "secure" string in MTK file
since we use ARM platform in which we call this "secure world"/
"secure command".

v3: https://lore.kernel.org/linux-mediatek/20231212024607.3681-1-yong.wu@mediatek.com/
1) Separate the secure heap to a common file(secure_heap.c) and mtk
special file (secure_heap_mtk.c), and put all the tee related code
into our special file.
2) About dt-binding, Add "mediatek," prefix since this is Mediatek TEE
firmware definition.
3) Remove the normal CMA heap which is a draft for qcom.
Rebase on v6.7-rc1.

v2: https://lore.kernel.org/linux-mediatek/20231111111559.8218-1-yong.wu@mediatek.com/
1) Move John's patches into the vcodec patchset since they use the new
dma heap interface directly.
https://lore.kernel.org/linux-mediatek/20231106120423.23364-1-yunfei.dong@mediatek.com/
2) Reword the dt-binding description.
3) Rename the heap name from mtk_svp to secure_mtk_cm.
This means the current vcodec/DRM upstream code doesn't match this.
4) Add a normal CMA heap. currently it should be a draft version.
5) Regarding the UUID, I still use hard code, but put it in a private
data which allow the others could set their own UUID. What's more, UUID
is necessary for the session with TEE. If we don't have it, we can't
communicate with the TEE, including the get_uuid interface, which tries
to make uuid more generic, not working. If there is other way to make
UUID more general, please free to tell me.

v1: https://lore.kernel.org/linux-mediatek/20230911023038.30649-1-yong.wu@mediatek.com/
Base on v6.6-rc1.

Yong Wu (7):
dt-bindings: reserved-memory: Add mediatek,dynamic-restricted-region
dma-buf: heaps: Initialize a restricted heap
dma-buf: heaps: restricted_heap: Add private heap ops
dma-buf: heaps: restricted_heap: Add dma_ops
dma-buf: heaps: restricted_heap: Add MediaTek restricted heap and
heap_init
dma-buf: heaps: restricted_heap_mtk: Add TEE memory service call
dma_buf: heaps: restricted_heap_mtk: Add a new CMA heap

.../mediatek,dynamic-restricted-region.yaml | 43 +++
drivers/dma-buf/heaps/Kconfig | 16 +
drivers/dma-buf/heaps/Makefile | 4 +-
drivers/dma-buf/heaps/restricted_heap.c | 237 +++++++++++++
drivers/dma-buf/heaps/restricted_heap.h | 43 +++
drivers/dma-buf/heaps/restricted_heap_mtk.c | 322 ++++++++++++++++++
6 files changed, 664 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/reserved-memory/mediatek,dynamic-restricted-region.yaml
create mode 100644 drivers/dma-buf/heaps/restricted_heap.c
create mode 100644 drivers/dma-buf/heaps/restricted_heap.h
create mode 100644 drivers/dma-buf/heaps/restricted_heap_mtk.c

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2.18.0