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Date: Wed, 31 Jan 2024 14:24:00 +0100
From: Joakim Bech <joakim.bech@linaro.org>
To: Yong Wu <yong.wu@mediatek.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Matthias Brugger <matthias.bgg@gmail.com>, christian.koenig@amd.com,
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Subject: Re: [PATCH v4 2/7] dma-buf: heaps: Initialize a restricted heap
Message-ID: <20240131132400.h3hklvnjjp3pelqz@pop-os.localdomain>
References: <20240112092014.23999-1-yong.wu@mediatek.com>
 <20240112092014.23999-3-yong.wu@mediatek.com>
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In-Reply-To: <20240112092014.23999-3-yong.wu@mediatek.com>

On Fri, Jan 12, 2024 at 05:20:09PM +0800, Yong Wu wrote:
> Initialize a restricted 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           |  9 ++++
>  drivers/dma-buf/heaps/Makefile          |  3 +-
>  drivers/dma-buf/heaps/restricted_heap.c | 67 +++++++++++++++++++++++++
>  drivers/dma-buf/heaps/restricted_heap.h | 22 ++++++++
>  4 files changed, 100 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/dma-buf/heaps/restricted_heap.c
>  create mode 100644 drivers/dma-buf/heaps/restricted_heap.h
> 
> diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-buf/heaps/Kconfig
> index a5eef06c4226..e54506f480ea 100644
> --- a/drivers/dma-buf/heaps/Kconfig
> +++ b/drivers/dma-buf/heaps/Kconfig
> @@ -12,3 +12,12 @@ 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_RESTRICTED
> +	bool "DMA-BUF Restricted Heap"
> +	depends on DMABUF_HEAPS
> +	help
> +	  Choose this option to enable dma-buf restricted heap. The purpose of this
> +	  heap is to manage buffers that are inaccessible to the kernel and user space.
> +	  There may be several ways to restrict it, for example it may be encrypted or
> +	  protected by a TEE or hypervisor. If in doubt, say N.
> diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-buf/heaps/Makefile
> index 974467791032..a2437c1817e2 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-$(CONFIG_DMABUF_HEAPS_RESTRICTED)	+= restricted_heap.o
> +obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)	+= system_heap.o
> diff --git a/drivers/dma-buf/heaps/restricted_heap.c b/drivers/dma-buf/heaps/restricted_heap.c
> new file mode 100644
> index 000000000000..fd7c82abd42e
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/restricted_heap.c
> @@ -0,0 +1,67 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * DMABUF restricted heap exporter
> + *
> + * Copyright (C) 2024 MediaTek Inc.
> + */
> +
> +#include <linux/dma-buf.h>
> +#include <linux/dma-heap.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +
> +#include "restricted_heap.h"
> +
> +static struct dma_buf *
> +restricted_heap_allocate(struct dma_heap *heap, unsigned long size,
> +			 unsigned long fd_flags, unsigned long heap_flags)
> +{
> +	struct restricted_buffer *restricted_buf;
> +	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> +	struct dma_buf *dmabuf;
> +	int ret;
> +
> +	restricted_buf = kzalloc(sizeof(*restricted_buf), GFP_KERNEL);
> +	if (!restricted_buf)
> +		return ERR_PTR(-ENOMEM);
> +
> +	restricted_buf->size = ALIGN(size, PAGE_SIZE);
> +	restricted_buf->heap = heap;
> +
> +	exp_info.exp_name = dma_heap_get_name(heap);
> +	exp_info.size = restricted_buf->size;
> +	exp_info.flags = fd_flags;
> +	exp_info.priv = restricted_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(restricted_buf);
> +	return ERR_PTR(ret);
> +}
> +
> +static const struct dma_heap_ops restricted_heap_ops = {
> +	.allocate = restricted_heap_allocate,
> +};
> +
> +int restricted_heap_add(struct restricted_heap *rstrd_heap)
>
Nothing wrong, but what about shortening rstrd_heap throughout the patch
set to "rheap", I would find that easier to read.

> +{
> +	struct dma_heap_export_info exp_info;
> +	struct dma_heap *heap;
> +
> +	exp_info.name = rstrd_heap->name;
> +	exp_info.ops = &restricted_heap_ops;
> +	exp_info.priv = (void *)rstrd_heap;
> +
> +	heap = dma_heap_add(&exp_info);
> +	if (IS_ERR(heap))
> +		return PTR_ERR(heap);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(restricted_heap_add);
> diff --git a/drivers/dma-buf/heaps/restricted_heap.h b/drivers/dma-buf/heaps/restricted_heap.h
> new file mode 100644
> index 000000000000..443028f6ba3b
> --- /dev/null
> +++ b/drivers/dma-buf/heaps/restricted_heap.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Restricted heap Header.
> + *
> + * Copyright (C) 2024 MediaTek, Inc.
> + */
> +
> +#ifndef _DMABUF_RESTRICTED_HEAP_H_
> +#define _DMABUF_RESTRICTED_HEAP_H_
> +
> +struct restricted_buffer {
> +	struct dma_heap		*heap;
> +	size_t			size;
> +};
> +
> +struct restricted_heap {
> +	const char		*name;
> +};
> +
> +int restricted_heap_add(struct restricted_heap *rstrd_heap);
> +
> +#endif
> -- 
> 2.25.1
> 

-- 
// Regards
Joakim