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path: root/drivers/vfio/Kconfig
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2021-08-26vfio: Use kconfig if XX/endif blocks instead of repeating 'depends on'Jason Gunthorpe
This results in less kconfig wordage and a simpler understanding of the required "depends on" to create the menu structure. The next patch increases the nesting level a lot so this is a nice preparatory simplification. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Link: https://lore.kernel.org/r/20210826103912.128972-13-yishaih@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2021-08-26vfio: Use select for eventfdJason Gunthorpe
If VFIO_VIRQFD is required then turn on eventfd automatically. The majority of kconfig users of the EVENTFD use select not depends on. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Link: https://lore.kernel.org/r/20210826103912.128972-12-yishaih@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2021-08-02vfio: Use config not menuconfig for VFIO_NOIOMMUJason Gunthorpe
VFIO_NOIOMMU is supposed to be an element in the VFIO menu, not start a new menu. Correct this copy-paste mistake. Fixes: 03a76b60f8ba ("vfio: Include No-IOMMU mode") Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Link: https://lore.kernel.org/r/0-v1-3f0b685c3679+478-vfio_menuconfig_jgg@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2021-03-16vfio: Depend on MMUJason Gunthorpe
VFIO_IOMMU_TYPE1 does not compile with !MMU: ../drivers/vfio/vfio_iommu_type1.c: In function 'follow_fault_pfn': ../drivers/vfio/vfio_iommu_type1.c:536:22: error: implicit declaration of function 'pte_write'; did you mean 'vfs_write'? [-Werror=implicit-function-declaration] So require it. Suggested-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Message-Id: <0-v1-02cb5500df6e+78-vfio_no_mmu_jgg@nvidia.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2021-03-16vfio: IOMMU_API should be selectedJason Gunthorpe
As IOMMU_API is a kconfig without a description (eg does not show in the menu) the correct operator is select not 'depends on'. Using 'depends on' for this kind of symbol means VFIO is not selectable unless some other random kconfig has already enabled IOMMU_API for it. Fixes: cba3345cc494 ("vfio: VFIO core") Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Message-Id: <1-v1-df057e0f92c3+91-vfio_arm_compile_test_jgg@nvidia.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2020-10-07vfio/fsl-mc: Add VFIO framework skeleton for fsl-mc devicesBharat Bhushan
DPAA2 (Data Path Acceleration Architecture) consists in mechanisms for processing Ethernet packets, queue management, accelerators, etc. The Management Complex (mc) is a hardware entity that manages the DPAA2 hardware resources. It provides an object-based abstraction for software drivers to use the DPAA2 hardware. The MC mediates operations such as create, discover, destroy of DPAA2 objects. The MC provides memory-mapped I/O command interfaces (MC portals) which DPAA2 software drivers use to operate on DPAA2 objects. A DPRC is a container object that holds other types of DPAA2 objects. Each object in the DPRC is a Linux device and bound to a driver. The MC-bus driver is a platform driver (different from PCI or platform bus). The DPRC driver does runtime management of a bus instance. It performs the initial scan of the DPRC and handles changes in the DPRC configuration (adding/removing objects). All objects inside a container share the same hardware isolation context, meaning that only an entire DPRC can be assigned to a virtual machine. When a container is assigned to a virtual machine, all the objects within that container are assigned to that virtual machine. The DPRC container assigned to the virtual machine is not allowed to change contents (add/remove objects) by the guest. The restriction is set by the host and enforced by the mc hardware. The DPAA2 objects can be directly assigned to the guest. However the MC portals (the memory mapped command interface to the MC) need to be emulated because there are commands that configure the interrupts and the isolation IDs which are virtual in the guest. Example: echo vfio-fsl-mc > /sys/bus/fsl-mc/devices/dprc.2/driver_override echo dprc.2 > /sys/bus/fsl-mc/drivers/vfio-fsl-mc/bind The dprc.2 is bound to the VFIO driver and all the objects within dprc.2 are going to be bound to the VFIO driver. This patch adds the infrastructure for VFIO support for fsl-mc devices. Subsequent patches will add support for binding and secure assigning these devices using VFIO. More details about the DPAA2 objects can be found here: Documentation/networking/device_drivers/freescale/dpaa2/overview.rst Signed-off-by: Bharat Bhushan <Bharat.Bhushan@nxp.com> Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2019-07-15docs: driver-api: add a series of orphaned documentsMauro Carvalho Chehab
There are lots of documents under Documentation/*.txt and a few other orphan documents elsehwere that belong to the driver-API book. Move them to their right place. Reviewed-by: Cornelia Huck <cohuck@redhat.com> # vfio-related parts Acked-by: Logan Gunthorpe <logang@deltatee.com> # switchtec Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-05-21treewide: Add SPDX license identifier - Makefile/KconfigThomas Gleixner
Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-19Make anon_inodes unconditionalDavid Howells
Make the anon_inodes facility unconditional so that it can be used by core VFS code and pidfd code. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> [christian@brauner.io: adapt commit message to mention pidfds] Signed-off-by: Christian Brauner <christian@brauner.io>
2018-09-25drivers/vfio: Allow type-1 IOMMU instantiation with all ARM/ARM64 IOMMUsGeert Uytterhoeven
Currently the type-1 IOMMU instantiation depends on "ARM_SMMU || ARM_SMMU_V3", while it applies to other ARM/ARM64 platforms with an IOMMU (e.g. Renesas VMSA-compatible IPMMUs). Instead of extending the list of IOMMU types on ARM platforms, replace the list by "ARM || ARM64", like other architectures do. The feature is still restricted to ARM/ARM64 platforms with an IOMMU by the dependency on IOMMU_API. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2017-02-08vfio: Fix build break when SPAPR_TCE_IOMMU=nMichael Ellerman
Currently the kconfig logic for VFIO_IOMMU_SPAPR_TCE and VFIO_SPAPR_EEH is broken when SPAPR_TCE_IOMMU=n. Leading to: warning: (VFIO) selects VFIO_IOMMU_SPAPR_TCE which has unmet direct dependencies (VFIO && SPAPR_TCE_IOMMU) warning: (VFIO) selects VFIO_IOMMU_SPAPR_TCE which has unmet direct dependencies (VFIO && SPAPR_TCE_IOMMU) drivers/vfio/vfio_iommu_spapr_tce.c:113:8: error: implicit declaration of function 'mm_iommu_find' This stems from the fact that VFIO selects VFIO_IOMMU_SPAPR_TCE, and although it has an if clause, the condition is not correct. We could fix it by doing select VFIO_IOMMU_SPAPR_TCE if SPAPR_TCE_IOMMU, but the cleaner fix is to drop the selects and tie VFIO_IOMMU_SPAPR_TCE to the value of VFIO, and express the dependencies in only once place. Do the same for VFIO_SPAPR_EEH. The end result is that the values of VFIO_IOMMU_SPAPR_TCE and VFIO_SPAPR_EEH follow the value of VFIO, except when SPAPR_TCE_IOMMU=n and/or EEH=n. Which is exactly what we want to happen. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2016-11-17vfio: Mediated device Core driverKirti Wankhede
Design for Mediated Device Driver: Main purpose of this driver is to provide a common interface for mediated device management that can be used by different drivers of different devices. This module provides a generic interface to create the device, add it to mediated bus, add device to IOMMU group and then add it to vfio group. Below is the high Level block diagram, with Nvidia, Intel and IBM devices as example, since these are the devices which are going to actively use this module as of now. +---------------+ | | | +-----------+ | mdev_register_driver() +--------------+ | | | +<------------------------+ __init() | | | mdev | | | | | | bus | +------------------------>+ |<-> VFIO user | | driver | | probe()/remove() | vfio_mdev.ko | APIs | | | | | | | +-----------+ | +--------------+ | | | MDEV CORE | | MODULE | | mdev.ko | | +-----------+ | mdev_register_device() +--------------+ | | | +<------------------------+ | | | | | | nvidia.ko |<-> physical | | | +------------------------>+ | device | | | | callback +--------------+ | | Physical | | | | device | | mdev_register_device() +--------------+ | | interface | |<------------------------+ | | | | | | i915.ko |<-> physical | | | +------------------------>+ | device | | | | callback +--------------+ | | | | | | | | mdev_register_device() +--------------+ | | | +<------------------------+ | | | | | | ccw_device.ko|<-> physical | | | +------------------------>+ | device | | | | callback +--------------+ | +-----------+ | +---------------+ Core driver provides two types of registration interfaces: 1. Registration interface for mediated bus driver: /** * struct mdev_driver - Mediated device's driver * @name: driver name * @probe: called when new device created * @remove:called when device removed * @driver:device driver structure * **/ struct mdev_driver { const char *name; int (*probe) (struct device *dev); void (*remove) (struct device *dev); struct device_driver driver; }; Mediated bus driver for mdev device should use this interface to register and unregister with core driver respectively: int mdev_register_driver(struct mdev_driver *drv, struct module *owner); void mdev_unregister_driver(struct mdev_driver *drv); Mediated bus driver is responsible to add/delete mediated devices to/from VFIO group when devices are bound and unbound to the driver. 2. Physical device driver interface This interface provides vendor driver the set APIs to manage physical device related work in its driver. APIs are : * dev_attr_groups: attributes of the parent device. * mdev_attr_groups: attributes of the mediated device. * supported_type_groups: attributes to define supported type. This is mandatory field. * create: to allocate basic resources in vendor driver for a mediated device. This is mandatory to be provided by vendor driver. * remove: to free resources in vendor driver when mediated device is destroyed. This is mandatory to be provided by vendor driver. * open: open callback of mediated device * release: release callback of mediated device * read : read emulation callback. * write: write emulation callback. * ioctl: ioctl callback. * mmap: mmap emulation callback. Drivers should use these interfaces to register and unregister device to mdev core driver respectively: extern int mdev_register_device(struct device *dev, const struct parent_ops *ops); extern void mdev_unregister_device(struct device *dev); There are no locks to serialize above callbacks in mdev driver and vfio_mdev driver. If required, vendor driver can have locks to serialize above APIs in their driver. Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Neo Jia <cjia@nvidia.com> Reviewed-by: Jike Song <jike.song@intel.com> Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2015-12-21vfio: Include No-IOMMU modeAlex Williamson
There is really no way to safely give a user full access to a DMA capable device without an IOMMU to protect the host system. There is also no way to provide DMA translation, for use cases such as device assignment to virtual machines. However, there are still those users that want userspace drivers even under those conditions. The UIO driver exists for this use case, but does not provide the degree of device access and programming that VFIO has. In an effort to avoid code duplication, this introduces a No-IOMMU mode for VFIO. This mode requires building VFIO with CONFIG_VFIO_NOIOMMU and enabling the "enable_unsafe_noiommu_mode" option on the vfio driver. This should make it very clear that this mode is not safe. Additionally, CAP_SYS_RAWIO privileges are necessary to work with groups and containers using this mode. Groups making use of this support are named /dev/vfio/noiommu-$GROUP and can only make use of the special VFIO_NOIOMMU_IOMMU for the container. Use of this mode, specifically binding a device without a native IOMMU group to a VFIO bus driver will taint the kernel and should therefore not be considered supported. This patch includes no-iommu support for the vfio-pci bus driver only. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com>
2015-12-04Revert: "vfio: Include No-IOMMU mode"Alex Williamson
Revert commit 033291eccbdb ("vfio: Include No-IOMMU mode") due to lack of a user. This was originally intended to fill a need for the DPDK driver, but uptake has been slow so rather than support an unproven kernel interface revert it and revisit when userspace catches up. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2015-11-13Merge tag 'vfio-v4.4-rc1' of git://github.com/awilliam/linux-vfioLinus Torvalds
Pull VFIO updates from Alex Williamson: - Use kernel interfaces for VPD emulation (Alex Williamson) - Platform fix for releasing IRQs (Eric Auger) - Type1 IOMMU always advertises PAGE_SIZE support when smaller mapping sizes are available (Eric Auger) - Platform fixes for incorrectly using copies of structures rather than pointers to structures (James Morse) - Rework platform reset modules, fix leak, and add AMD xgbe reset module (Eric Auger) - Fix vfio_device_get_from_name() return value (Joerg Roedel) - No-IOMMU interface (Alex Williamson) - Fix potential out of bounds array access in PCI config handling (Dan Carpenter) * tag 'vfio-v4.4-rc1' of git://github.com/awilliam/linux-vfio: vfio/pci: make an array larger vfio: Include No-IOMMU mode vfio: Fix bug in vfio_device_get_from_name() VFIO: platform: reset: AMD xgbe reset module vfio: platform: reset: calxedaxgmac: fix ioaddr leak vfio: platform: add dev_info on device reset vfio: platform: use list of registered reset function vfio: platform: add compat in vfio_platform_device vfio: platform: reset: calxedaxgmac: add reset function registration vfio: platform: introduce module_vfio_reset_handler macro vfio: platform: add capability to register a reset function vfio: platform: introduce vfio-platform-base module vfio/platform: store mapped memory in region, instead of an on-stack copy vfio/type1: handle case where IOMMU does not support PAGE_SIZE size VFIO: platform: clear IRQ_NOAUTOEN when de-assigning the IRQ vfio/pci: Use kernel VPD access functions vfio: Whitelist PCI bridges
2015-11-04vfio: Include No-IOMMU modeAlex Williamson
There is really no way to safely give a user full access to a DMA capable device without an IOMMU to protect the host system. There is also no way to provide DMA translation, for use cases such as device assignment to virtual machines. However, there are still those users that want userspace drivers even under those conditions. The UIO driver exists for this use case, but does not provide the degree of device access and programming that VFIO has. In an effort to avoid code duplication, this introduces a No-IOMMU mode for VFIO. This mode requires building VFIO with CONFIG_VFIO_NOIOMMU and enabling the "enable_unsafe_noiommu_mode" option on the vfio driver. This should make it very clear that this mode is not safe. Additionally, CAP_SYS_RAWIO privileges are necessary to work with groups and containers using this mode. Groups making use of this support are named /dev/vfio/noiommu-$GROUP and can only make use of the special VFIO_NOIOMMU_IOMMU for the container. Use of this mode, specifically binding a device without a native IOMMU group to a VFIO bus driver will taint the kernel and should therefore not be considered supported. This patch includes no-iommu support for the vfio-pci bus driver only. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com>
2015-10-01vfio: Register/unregister irq_bypass_producerFeng Wu
This patch adds the registration/unregistration of an irq_bypass_producer for MSI/MSIx on vfio pci devices. Acked-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Feng Wu <feng.wu@intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2015-05-29drivers/vfio: Allow type-1 IOMMU instantiation on top of an ARM SMMUv3Will Deacon
The ARM SMMUv3 driver is compatible with the notion of a type-1 IOMMU in VFIO. This patch allows VFIO_IOMMU_TYPE1 to be selected if ARM_SMMU_V3=y. Signed-off-by: Will Deacon <will.deacon@arm.com> Acked-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Joerg Roedel <jroedel@suse.de>
2015-03-17vfio: Split virqfd into a separate module for vfio bus driversAlex Williamson
An unintended consequence of commit 42ac9bd18d4f ("vfio: initialize the virqfd workqueue in VFIO generic code") is that the vfio module is renamed to vfio_core so that it can include both vfio and virqfd. That's a user visible change that may break module loading scritps and it imposes eventfd support as a dependency on the core vfio code, which it's really not. virqfd is intended to be provided as a service to vfio bus drivers, so instead of wrapping it into vfio.ko, we can make it a stand-alone module toggled by vfio bus drivers. This has the additional benefit of removing initialization and exit from the core vfio code. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2015-03-16vfio: platform: add the VFIO PLATFORM module to KconfigAntonios Motakis
Enable building the VFIO PLATFORM driver that allows to use Linux platform devices with VFIO. Signed-off-by: Antonios Motakis <a.motakis@virtualopensystems.com> Signed-off-by: Baptiste Reynal <b.reynal@virtualopensystems.com> Reviewed-by: Eric Auger <eric.auger@linaro.org> Tested-by: Eric Auger <eric.auger@linaro.org> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2014-11-14drivers/vfio: allow type-1 IOMMU instantiation on top of an ARM SMMUWill Deacon
The ARM SMMU driver is compatible with the notion of a type-1 IOMMU in VFIO. This patch allows VFIO_IOMMU_TYPE1 to be selected if ARM_SMMU=y. Signed-off-by: Will Deacon <will.deacon@arm.com> [aw: update for existing S390 patch] Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2014-11-07vfio: make vfio run on s390Frank Blaschka
add Kconfig switch to hide INTx add Kconfig switch to let vfio announce PCI BARs are not mapable Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2014-08-08drivers/vfio: Fix EEH build errorGavin Shan
The VFIO related components could be built as dynamic modules. Unfortunately, CONFIG_EEH can't be configured to "m". The patch fixes the build errors when configuring VFIO related components as dynamic modules as follows: CC [M] drivers/vfio/vfio_iommu_spapr_tce.o In file included from drivers/vfio/vfio.c:33:0: include/linux/vfio.h:101:43: warning: ‘struct pci_dev’ declared \ inside parameter list [enabled by default] : WRAP arch/powerpc/boot/zImage.pseries WRAP arch/powerpc/boot/zImage.maple WRAP arch/powerpc/boot/zImage.pmac WRAP arch/powerpc/boot/zImage.epapr MODPOST 1818 modules ERROR: ".vfio_spapr_iommu_eeh_ioctl" [drivers/vfio/vfio_iommu_spapr_tce.ko]\ undefined! ERROR: ".vfio_spapr_pci_eeh_open" [drivers/vfio/pci/vfio-pci.ko] undefined! ERROR: ".vfio_spapr_pci_eeh_release" [drivers/vfio/pci/vfio-pci.ko] undefined! Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2014-03-27vfio: always select ANON_INODESArnd Bergmann
The vfio code cannot be built when CONFIG_ANON_INODES is disabled, so this enforces the symbol to be enabled through Kconfig. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2013-06-20powerpc/vfio: Enable on pSeries platformAlexey Kardashevskiy
The enables VFIO on the pSeries platform, enabling user space programs to access PCI devices directly. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-06-20powerpc/vfio: Implement IOMMU driver for VFIOAlexey Kardashevskiy
VFIO implements platform independent stuff such as a PCI driver, BAR access (via read/write on a file descriptor or direct mapping when possible) and IRQ signaling. The platform dependent part includes IOMMU initialization and handling. This implements an IOMMU driver for VFIO which does mapping/unmapping pages for the guest IO and provides information about DMA window (required by a POWER guest). Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2012-07-31vfio: Add PCI device driverAlex Williamson
Add PCI device support for VFIO. PCI devices expose regions for accessing config space, I/O port space, and MMIO areas of the device. PCI config access is virtualized in the kernel, allowing us to ensure the integrity of the system, by preventing various accesses while reducing duplicate support across various userspace drivers. I/O port supports read/write access while MMIO also supports mmap of sufficiently sized regions. Support for INTx, MSI, and MSI-X interrupts are provided using eventfds to userspace. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-07-31vfio: Type1 IOMMU implementationAlex Williamson
This VFIO IOMMU backend is designed primarily for AMD-Vi and Intel VT-d hardware, but is potentially usable by anything supporting similar mapping functionality. We arbitrarily call this a Type1 backend for lack of a better name. This backend has no IOVA or host memory mapping restrictions for the user and is optimized for relatively static mappings. Mapped areas are pinned into system memory. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2012-07-31vfio: VFIO coreAlex Williamson
VFIO is a secure user level driver for use with both virtual machines and user level drivers. VFIO makes use of IOMMU groups to ensure the isolation of devices in use, allowing unprivileged user access. It's intended that VFIO will replace KVM device assignment and UIO drivers (in cases where the target platform includes a sufficiently capable IOMMU). New in this version of VFIO is support for IOMMU groups managed through the IOMMU core as well as a rework of the API, removing the group merge interface. We now go back to a model more similar to original VFIO with UIOMMU support where the file descriptor obtained from /dev/vfio/vfio allows access to the IOMMU, but only after a group is added, avoiding the previous privilege issues with this type of model. IOMMU support is also now fully modular as IOMMUs have vastly different interface requirements on different platforms. VFIO users are able to query and initialize the IOMMU model of their choice. Please see the follow-on Documentation commit for further description and usage example. Signed-off-by: Alex Williamson <alex.williamson@redhat.com>