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Stefano Stabellini
4ec51e8780
This commit creates a new doc to document how to do passthrough without IOMMU. Signed-off-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Penny Zheng <penny.zheng@arm.com> Acked-by: Julien Grall <jgrall@amazon.com> Tested-by: Stefano Stabellini <sstabellini@kernel.org>
53 lines
1.6 KiB
Plaintext
53 lines
1.6 KiB
Plaintext
Request Device Assignment without IOMMU support
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===============================================
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*WARNING:
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Users should be aware that it is not always secure to assign a device without
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IOMMU protection.
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When the device is not protected by the IOMMU, the administrator should make
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sure that:
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1. The device is assigned to a trusted guest.
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2. Users have additional security mechanism on the platform.
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This document assumes that the IOMMU is absent from the system or it is
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disabled (status = "disabled" in device tree).
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Add xen,force-assign-without-iommu; to the device tree snippet:
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ethernet: ethernet@ff0e0000 {
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compatible = "cdns,zynqmp-gem";
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xen,path = "/amba/ethernet@ff0e0000";
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xen,reg = <0x0 0xff0e0000 0x1000 0x0 0xff0e0000>;
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xen,force-assign-without-iommu;
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};
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Request 1:1 memory mapping for the domain on static allocation
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==============================================================
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Add a direct-map property under the appropriate /chosen/domU node which
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is also statically allocated with physical memory ranges through
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xen,static-mem property as its guest RAM.
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Below is an example on how to specify the 1:1 memory mapping for the domain
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on static allocation in the device-tree:
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/ {
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chosen {
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domU1 {
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compatible = "xen,domain";
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#address-cells = <0x2>;
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#size-cells = <0x2>;
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cpus = <2>;
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memory = <0x0 0x80000>;
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#xen,static-mem-address-cells = <0x1>;
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#xen,static-mem-size-cells = <0x1>;
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xen,static-mem = <0x30000000 0x20000000>;
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direct-map;
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...
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};
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};
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};
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Besides reserving a 512MB region starting at the host physical address
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0x30000000 to DomU1, it also requests 1:1 memory mapping.
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