[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v5 11/11] xen/docs: Document how to do passthrough without IOMMU
From: Stefano Stabellini <sstabellini@xxxxxxxxxx> This commit creates a new doc to document how to do passthrough without IOMMU. Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx> Tested-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> --- v2 changes: - nothing changed --- v3 changes: - nothing changed --- v4 changes: - nothing changed --- v5 changes: - nothing changed --- docs/misc/arm/passthrough-noiommu.txt | 52 +++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 docs/misc/arm/passthrough-noiommu.txt diff --git a/docs/misc/arm/passthrough-noiommu.txt b/docs/misc/arm/passthrough-noiommu.txt new file mode 100644 index 0000000000..3e2ef21ad7 --- /dev/null +++ b/docs/misc/arm/passthrough-noiommu.txt @@ -0,0 +1,52 @@ +Request Device Assignment without IOMMU support +=============================================== + +*WARNING: +Users should be aware that it is not always secure to assign a device without +IOMMU protection. +When the device is not protected by the IOMMU, the administrator should make +sure that: + 1. The device is assigned to a trusted guest. + 2. Users have additional security mechanism on the platform. + +This document assumes that the IOMMU is absent from the system or it is +disabled (status = "disabled" in device tree). + +Add xen,force-assign-without-iommu; to the device tree snippet: + +ethernet: ethernet@ff0e0000 { + compatible = "cdns,zynqmp-gem"; + xen,path = "/amba/ethernet@ff0e0000"; + xen,reg = <0x0 0xff0e0000 0x1000 0x0 0xff0e0000>; + xen,force-assign-without-iommu; +}; + +Request 1:1 memory mapping for the domain on static allocation +============================================================== + +Add a direct-map property under the appropriate /chosen/domU node which +is also statically allocated with physical memory ranges through +xen,static-mem property as its guest RAM. + +Below is an example on how to specify the 1:1 memory mapping for the domain +on static allocation in the device-tree: + +/ { + chosen { + domU1 { + compatible = "xen,domain"; + #address-cells = <0x2>; + #size-cells = <0x2>; + cpus = <2>; + memory = <0x0 0x80000>; + #xen,static-mem-address-cells = <0x1>; + #xen,static-mem-size-cells = <0x1>; + xen,static-mem = <0x30000000 0x20000000>; + direct-map; + ... + }; + }; +}; + +Besides reserving a 512MB region starting at the host physical address +0x30000000 to DomU1, it also requests 1:1 memory mapping. -- 2.25.1
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