Re: [PATCH v2 1/8] dma-buf: heaps: Initialize a secure heap

[Jeffrey Kardatzke <jkardatzke@google.com>]

On Sat, Nov 11, 2023 at 3:16 AM Yong Wu <yong.wu@mediatek.com> wrote:
>
> Initialize a secure 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       |  7 +++
>  drivers/dma-buf/heaps/Makefile      |  1 +
>  drivers/dma-buf/heaps/secure_heap.c | 98 +++++++++++++++++++++++++++++
>  3 files changed, 106 insertions(+)
>  create mode 100644 drivers/dma-buf/heaps/secure_heap.c
>
> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> index a5eef06c4226..e358bf711145 100644
> --- a/drivers/dma-buf/heaps/Kconfig
> +++ b/drivers/dma-buf/heaps/Kconfig
> @@ -12,3 +12,10 @@ 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_SECURE
> +       bool "DMA-BUF Secure Heap"
> +       depends on DMABUF_HEAPS && TEE
> +       help
> +         Choose this option to enable dma-buf secure heap. This heap is backed by
> +         TEE client interfaces or CMA. If in doubt, say N.

Remove the mention of TEE and CMA from this.

You should probably add two KConfig options. One is for
DMABUF_HEAPS_SECURE which is for the framework for secure heaps. The
other one should be:

config MTK_DMABUF_HEAPS_SECURE
    bool "Mediatek DMA-BUF Secure Heap"
    depends on DMABUF_HEAPS_SECURE && TEE
    help
        Enables secure dma-buf heaps for Mediatek platforms.


> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> index 974467791032..b1ad9d1f2fbe 100644
> --- a/drivers/dma-buf/heaps/Makefile
> +++ b/drivers/dma-buf/heaps/Makefile
> @@ -1,3 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_DMABUF_HEAPS_SECURE)      += secure_heap.o
>  obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)      += system_heap.o
>  obj-$(CONFIG_DMABUF_HEAPS_CMA)         += cma_heap.o
> diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-buf/heaps/secure_heap.c
> new file mode 100644
> index 000000000000..a634051a0a67
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/secure_heap.c
> @@ -0,0 +1,98 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * DMABUF 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>
> +
> +enum secure_memory_type {
> +       /*
> +        * MediaTek static chunk memory carved out for TrustZone. The memory
> +        * management is inside the TEE.
> +        */
> +       SECURE_MEMORY_TYPE_MTK_CM_TZ    = 1,

Mediatek specific code for secure dma heaps should go into a new file
(maybe secure_heap_mtk.c which the MTK_DMABUF_HEAPS_SECURE option
enables).

> +};
> +
> +struct secure_buffer {
> +       struct dma_heap                 *heap;
> +       size_t                          size;
> +};
> +
> +struct secure_heap {
> +       const char                      *name;
> +       const enum secure_memory_type   mem_type;
secure_memory_type is going to be in the vendor specific
implementation, I don't think you need it in the framework.

> +};

You should probably move these to a <linux/dma-heap-secure.h> file so
they can be shared by the framework and the specific implementation
(in this case vendor specific).

> +
> +static struct dma_buf *
> +secure_heap_allocate(struct dma_heap *heap, unsigned long size,
> +                    unsigned long fd_flags, unsigned long heap_flags)
> +{
> +       struct secure_buffer *sec_buf;
> +       DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +       struct dma_buf *dmabuf;
> +       int ret;
> +
> +       sec_buf = kzalloc(sizeof(*sec_buf), GFP_KERNEL);
> +       if (!sec_buf)
> +               return ERR_PTR(-ENOMEM);
> +
> +       sec_buf->size = ALIGN(size, PAGE_SIZE);
> +       sec_buf->heap = heap;
> +
> +       exp_info.exp_name = dma_heap_get_name(heap);
> +       exp_info.size = sec_buf->size;
> +       exp_info.flags = fd_flags;
> +       exp_info.priv = sec_buf;
> +
> +       dmabuf = dma_buf_export(&exp_info);
> +       if (IS_ERR(dmabuf)) {
> +               ret = PTR_ERR(dmabuf);
> +               goto err_free_buf;
> +       }
> +
> +       return dmabuf;
> +
> +err_free_buf:
> +       kfree(sec_buf);
> +       return ERR_PTR(ret);
> +}
> +
> +static const struct dma_heap_ops sec_heap_ops = {
> +       .allocate = secure_heap_allocate,
> +};
> +
> +static struct secure_heap secure_heaps[] = {
> +       {
> +               .name           = "secure_mtk_cm",
> +               .mem_type       = SECURE_MEMORY_TYPE_MTK_CM_TZ,
> +       },
> +};

Move this to the vendor specific implementation.

> +
> +static int secure_heap_init(void)
> +{
> +       struct secure_heap *sec_heap = secure_heaps;
> +       struct dma_heap_export_info exp_info;
> +       struct dma_heap *heap;
> +       unsigned int i;
> +
> +       for (i = 0; i < ARRAY_SIZE(secure_heaps); i++, sec_heap++) {
> +               exp_info.name = sec_heap->name;
> +               exp_info.ops = &sec_heap_ops;
> +               exp_info.priv = (void *)sec_heap;
> +
> +               heap = dma_heap_add(&exp_info);
> +               if (IS_ERR(heap))
> +                       return PTR_ERR(heap);
> +       }
> +       return 0;
> +}

secure_heap_init should take a 'struct secure_heap*' as an argument
and be defined in dma-heap-secure.h.

> +
> +module_init(secure_heap_init);
> +MODULE_DESCRIPTION("Secure Heap Driver");
> +MODULE_LICENSE("GPL");

Remove from this file, it should go in the specific implementations.

> --
> 2.25.1
>