cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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shared-dma-pool.yaml (3251B)

      1# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
      2%YAML 1.2
      3---
      4$id: http://devicetree.org/schemas/reserved-memory/shared-dma-pool.yaml#
      5$schema: http://devicetree.org/meta-schemas/core.yaml#
      6
      7title: /reserved-memory DMA pool node bindings
      8
      9maintainers:
     10  - devicetree-spec@vger.kernel.org
     11
     12allOf:
     13  - $ref: "reserved-memory.yaml"
     14
     15properties:
     16  compatible:
     17    oneOf:
     18      - const: shared-dma-pool
     19        description: >
     20          This indicates a region of memory meant to be used as a shared
     21          pool of DMA buffers for a set of devices. It can be used by an
     22          operating system to instantiate the necessary pool management
     23          subsystem if necessary.
     24
     25      - const: restricted-dma-pool
     26        description: >
     27          This indicates a region of memory meant to be used as a pool
     28          of restricted DMA buffers for a set of devices. The memory
     29          region would be the only region accessible to those devices.
     30          When using this, the no-map and reusable properties must not
     31          be set, so the operating system can create a virtual mapping
     32          that will be used for synchronization. The main purpose for
     33          restricted DMA is to mitigate the lack of DMA access control
     34          on systems without an IOMMU, which could result in the DMA
     35          accessing the system memory at unexpected times and/or
     36          unexpected addresses, possibly leading to data leakage or
     37          corruption. The feature on its own provides a basic level of
     38          protection against the DMA overwriting buffer contents at
     39          unexpected times. However, to protect against general data
     40          leakage and system memory corruption, the system needs to
     41          provide way to lock down the memory access, e.g., MPU. Note
     42          that since coherent allocation needs remapping, one must set
     43          up another device coherent pool by shared-dma-pool and use
     44          dma_alloc_from_dev_coherent instead for atomic coherent
     45          allocation.
     46
     47  linux,cma-default:
     48    type: boolean
     49    description: >
     50      If this property is present, then Linux will use the region for
     51      the default pool of the contiguous memory allocator.
     52
     53  linux,dma-default:
     54    type: boolean
     55    description: >
     56      If this property is present, then Linux will use the region for
     57      the default pool of the consistent DMA allocator.
     58
     59if:
     60  properties:
     61    compatible:
     62      contains:
     63        const: restricted-dma-pool
     64then:
     65  properties:
     66    no-map: false
     67    reusable: false
     68
     69unevaluatedProperties: false
     70
     71examples:
     72  - |
     73      reserved-memory {
     74          #address-cells = <1>;
     75          #size-cells = <1>;
     76          ranges;
     77
     78          /* global autoconfigured region for contiguous allocations */
     79          linux,cma {
     80              compatible = "shared-dma-pool";
     81              reusable;
     82              size = <0x4000000>;
     83              alignment = <0x2000>;
     84              linux,cma-default;
     85          };
     86
     87          display_reserved: framebuffer@78000000 {
     88              reg = <0x78000000 0x800000>;
     89          };
     90
     91          restricted_dma_reserved: restricted-dma-pool@50000000 {
     92              compatible = "restricted-dma-pool";
     93              reg = <0x50000000 0x4000000>;
     94          };
     95      };
     96
     97...