From: Stefano Stabellini <sstabellini@kernel.org>
To: Claire Chang <tientzu@chromium.org>
Cc: Rob Herring <robh+dt@kernel.org>,
mpe@ellerman.id.au, Joerg Roedel <joro@8bytes.org>,
Will Deacon <will@kernel.org>,
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Subject: Re: [PATCH v12 11/12] dt-bindings: of: Add restricted DMA pool
Date: Wed, 16 Jun 2021 17:09:29 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.2106161651290.24906@sstabellini-ThinkPad-T480s> (raw)
In-Reply-To: <20210616062157.953777-12-tientzu@chromium.org>
On Wed, 16 Jun 2021, Claire Chang wrote:
> Introduce the new compatible string, restricted-dma-pool, for restricted
> DMA. One can specify the address and length of the restricted DMA memory
> region by restricted-dma-pool in the reserved-memory node.
>
> Signed-off-by: Claire Chang <tientzu@chromium.org>
> ---
> .../reserved-memory/reserved-memory.txt | 36 +++++++++++++++++--
> 1 file changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
> index e8d3096d922c..46804f24df05 100644
> --- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
> +++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
> @@ -51,6 +51,23 @@ compatible (optional) - standard definition
> used as a shared pool of DMA buffers for a set of devices. It can
> be used by an operating system to instantiate the necessary pool
> management subsystem if necessary.
> + - restricted-dma-pool: This indicates a region of memory meant to be
> + used as a pool of restricted DMA buffers for a set of devices. The
> + memory region would be the only region accessible to those devices.
> + When using this, the no-map and reusable properties must not be set,
> + so the operating system can create a virtual mapping that will be used
> + for synchronization. The main purpose for restricted DMA is to
> + mitigate the lack of DMA access control on systems without an IOMMU,
> + which could result in the DMA accessing the system memory at
> + unexpected times and/or unexpected addresses, possibly leading to data
> + leakage or corruption. The feature on its own provides a basic level
> + of protection against the DMA overwriting buffer contents at
> + unexpected times. However, to protect against general data leakage and
> + system memory corruption, the system needs to provide way to lock down
> + the memory access, e.g., MPU. Note that since coherent allocation
> + needs remapping, one must set up another device coherent pool by
> + shared-dma-pool and use dma_alloc_from_dev_coherent instead for atomic
> + coherent allocation.
> - vendor specific string in the form <vendor>,[<device>-]<usage>
> no-map (optional) - empty property
> - Indicates the operating system must not create a virtual mapping
> @@ -85,10 +102,11 @@ memory-region-names (optional) - a list of names, one for each corresponding
>
> Example
> -------
> -This example defines 3 contiguous regions are defined for Linux kernel:
> +This example defines 4 contiguous regions for Linux kernel:
> one default of all device drivers (named linux,cma@72000000 and 64MiB in size),
> -one dedicated to the framebuffer device (named framebuffer@78000000, 8MiB), and
> -one for multimedia processing (named multimedia-memory@77000000, 64MiB).
> +one dedicated to the framebuffer device (named framebuffer@78000000, 8MiB),
> +one for multimedia processing (named multimedia-memory@77000000, 64MiB), and
> +one for restricted dma pool (named restricted_dma_reserved@0x50000000, 64MiB).
>
> / {
> #address-cells = <1>;
> @@ -120,6 +138,11 @@ one for multimedia processing (named multimedia-memory@77000000, 64MiB).
> compatible = "acme,multimedia-memory";
> reg = <0x77000000 0x4000000>;
> };
> +
> + restricted_dma_reserved: restricted_dma_reserved {
> + compatible = "restricted-dma-pool";
> + reg = <0x50000000 0x4000000>;
> + };
> };
>
> /* ... */
> @@ -138,4 +161,11 @@ one for multimedia processing (named multimedia-memory@77000000, 64MiB).
> memory-region = <&multimedia_reserved>;
> /* ... */
> };
> +
> + pcie_device: pcie_device@0,0 {
> + reg = <0x83010000 0x0 0x00000000 0x0 0x00100000
> + 0x83010000 0x0 0x00100000 0x0 0x00100000>;
> + memory-region = <&restricted_dma_mem_reserved>;
Shouldn't it be &restricted_dma_reserved ?
next prev parent reply other threads:[~2021-06-17 0:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-16 6:21 [PATCH v12 00/12] Restricted DMA Claire Chang
2021-06-16 6:21 ` [PATCH v12 01/12] swiotlb: Refactor swiotlb init functions Claire Chang
2021-06-16 6:21 ` [PATCH v12 02/12] swiotlb: Refactor swiotlb_create_debugfs Claire Chang
2021-06-16 6:21 ` [PATCH v12 03/12] swiotlb: Set dev->dma_io_tlb_mem to the swiotlb pool used Claire Chang
2021-06-16 6:21 ` [PATCH v12 04/12] swiotlb: Update is_swiotlb_buffer to add a struct device argument Claire Chang
2021-06-16 6:21 ` [PATCH v12 05/12] swiotlb: Update is_swiotlb_active " Claire Chang
2021-06-16 6:21 ` [PATCH v12 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing Claire Chang
2021-06-16 7:39 ` Christoph Hellwig
2021-06-17 0:47 ` Stefano Stabellini
2021-06-16 6:21 ` [PATCH v12 07/12] swiotlb: Move alloc_size to swiotlb_find_slots Claire Chang
2021-06-16 6:21 ` [PATCH v12 08/12] swiotlb: Refactor swiotlb_tbl_unmap_single Claire Chang
2021-06-16 6:21 ` [PATCH v12 09/12] swiotlb: Add restricted DMA alloc/free support Claire Chang
2021-06-16 7:39 ` Christoph Hellwig
2021-06-16 6:21 ` [PATCH v12 10/12] swiotlb: Add restricted DMA pool initialization Claire Chang
2021-06-16 6:21 ` [PATCH v12 11/12] dt-bindings: of: Add restricted DMA pool Claire Chang
2021-06-17 0:09 ` Stefano Stabellini [this message]
2021-06-16 6:21 ` [PATCH v12 12/12] of: Add plumbing for " Claire Chang
2021-06-16 12:08 ` [PATCH v12 00/12] Restricted DMA Will Deacon
2021-06-17 6:40 ` Claire Chang
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