Re: [PATCH 4/9] dma-buf: heaps: Initialise MediaTek secure heap

["Yong Wu (吴勇)" <Yong.Wu@mediatek.com>]

On Thu, 2023-10-19 at 10:15 +0530, Vijayanand Jitta wrote:
>  	 
> External email : Please do not click links or open attachments until
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> 
> On 9/11/2023 8:00 AM, Yong Wu wrote:
> > Initialise a mtk_svp heap. Currently just add a null heap, Prepare
> for
> > the later patches.
> > 
> > Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> > ---
> >  drivers/dma-buf/heaps/Kconfig           |  8 ++
> >  drivers/dma-buf/heaps/Makefile          |  1 +
> >  drivers/dma-buf/heaps/mtk_secure_heap.c | 99
> +++++++++++++++++++++++++
> >  3 files changed, 108 insertions(+)
> >  create mode 100644 drivers/dma-buf/heaps/mtk_secure_heap.c
> > 
> > diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-
> buf/heaps/Kconfig
> > index a5eef06c4226..729c0cf3eb7c 100644
> > --- a/drivers/dma-buf/heaps/Kconfig
> > +++ b/drivers/dma-buf/heaps/Kconfig
> > @@ -12,3 +12,11 @@ config DMABUF_HEAPS_CMA
> >    Choose this option to enable dma-buf CMA heap. This heap is
> backed
> >    by the Contiguous Memory Allocator (CMA). If your system has
> these
> >    regions, you should say Y here.
> > +
> > +config DMABUF_HEAPS_MTK_SECURE
> > +bool "DMA-BUF MediaTek Secure Heap"
> > +depends on DMABUF_HEAPS && TEE
> > +help
> > +  Choose this option to enable dma-buf MediaTek secure heap for
> Secure
> > +  Video Path. This heap is backed by TEE client interfaces. If in
> > +  doubt, say N.
> > diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-
> buf/heaps/Makefile
> > index 974467791032..df559dbe33fe 100644
> > --- a/drivers/dma-buf/heaps/Makefile
> > +++ b/drivers/dma-buf/heaps/Makefile
> > @@ -1,3 +1,4 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >  obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)+= system_heap.o
> >  obj-$(CONFIG_DMABUF_HEAPS_CMA)+= cma_heap.o
> > +obj-$(CONFIG_DMABUF_HEAPS_MTK_SECURE)+= mtk_secure_heap.o
> > diff --git a/drivers/dma-buf/heaps/mtk_secure_heap.c b/drivers/dma-
> buf/heaps/mtk_secure_heap.c
> > new file mode 100644
> > index 000000000000..bbf1c8dce23e
> > --- /dev/null
> > +++ b/drivers/dma-buf/heaps/mtk_secure_heap.c
> > @@ -0,0 +1,99 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * DMABUF mtk_secure_heap exporter
> > + *
> > + * Copyright (C) 2023 MediaTek Inc.
> > + */
> > +
> > +#include <linux/dma-buf.h>
> > +#include <linux/dma-heap.h>
> > +#include <linux/err.h>
> > +#include <linux/module.h>
> > +#include <linux/slab.h>
> > +
> > +/*
> > + * MediaTek secure (chunk) memory type
> > + *
> > + * @KREE_MEM_SEC_CM_TZ: static chunk memory carved out for
> trustzone.
> > + */
> > +enum kree_mem_type {
> > +KREE_MEM_SEC_CM_TZ = 1,
> > +};
> > +
> > +struct mtk_secure_heap_buffer {
> > +struct dma_heap*heap;
> > +size_tsize;
> > +};
> > +
> > +struct mtk_secure_heap {
> > +const char*name;
> > +const enum kree_mem_type mem_type;
> > +};
> > +
> > +static struct dma_buf *
> > +mtk_sec_heap_allocate(struct dma_heap *heap, size_t size,
> > +      unsigned long fd_flags, unsigned long heap_flags)
> > +{
> > +struct mtk_secure_heap_buffer *sec_buf;
> > +DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> > +struct dma_buf *dmabuf;
> > +int ret;
> > +
> > +sec_buf = kzalloc(sizeof(*sec_buf), GFP_KERNEL);
> 
> As we know, kzalloc can only allocate 4MB at max. So, secure heap has
> this limitation.
> can we have a way to allocate more memory in secure heap ? maybe
> similar to how system heap does?

This is just the size of a internal structure. I guess you mean the
secure memory size here. Regarding secure memory allocating flow, our
flow may be different with yours.

Let me explain our flow, we have two secure buffer types(heaps).
a) mtk_svp
b) mtk_svp_cma which requires the cma binding.

The memory management of both is inside the TEE. We only need to tell
the TEE which type and size of buffer we want, and then the TEE will
perform and return the memory handle to the kernel. The
kzalloc/alloc_pages is for the normal buffers.

Regarding the CMA buffer, we only call cma_alloc once, and its
management is also within the TEE.

> 
> Thanks,
> Vijay
>