docs/specs/riscv-iommu.rst

6 QEMU implements a RISC-V IOMMU emulation based on the RISC-V IOMMU spec
9 The emulation includes a PCI reference device (riscv-iommu-pci) and a platform
10 bus device (riscv-iommu-sys) that QEMU RISC-V boards can use.  The 'virt'
16 This device implements the RISC-V IOMMU emulation as recommended by the section
20 As a reference device it doesn't implement anything outside of the specification,
23 To include the device in the 'virt' machine:
29 This will add a RISC-V IOMMU PCI device in the board following any additional
30 PCI parameters (like PCI bus address).  The behavior of the RISC-V IOMMU is
31 defined by the spec but its operation is OS dependent.
33 As of this writing the existing Linux kernel support `linux-v8`_, not yet merged,
34 does not have support for features like VFIO passthrough.  The IOMMU emulation
37 enable features like KVM VFIO passthrough with irqbypass.  Until the kernel support
38 is feature complete feel free to use the kernel available in the Ventana Micro Systems
41 The current Linux kernel support will use the IOMMU device to create IOMMU groups
42 with any eligible cards available in the system, regardless of factors such as the
43 order in which the devices are added in the command line.
45 This means that these command lines are equivalent as far as the current
64 Both will create iommu groups for the two e1000e cards.
66 Another thing to notice on `linux-v8`_ and `ventana-linux`_ is that the kernel driver
68 use the riscv-iommu-pci device with the existing kernel support we need to emulate
76 Several options are available to control the capabilities of the device, namely:
78 - "bus": the bus that the IOMMU device uses
79 - "ioatc-limit": size of the Address Translation Cache (default to 2Mb)
91 This device implements the RISC-V IOMMU emulation as a platform bus device that
94 For the 'virt' board the device is disabled by default.  To enable it use the
101 There is no options to configure the capabilities of this device in the 'virt'
102 board using the QEMU command line.  The device is configured with the following