diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/driver-api/vfio.rst | 147 | ||||
| -rw-r--r-- | Documentation/networking/device_drivers/ethernet/amd/pds_vfio_pci.rst | 79 | ||||
| -rw-r--r-- | Documentation/networking/device_drivers/ethernet/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/virt/kvm/devices/vfio.rst | 47 |
4 files changed, 255 insertions, 19 deletions
diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst index 68abc089d6dd..633d11c7fa71 100644 --- a/Documentation/driver-api/vfio.rst +++ b/Documentation/driver-api/vfio.rst @@ -239,6 +239,137 @@ group and can access them as follows:: /* Gratuitous device reset and go... */ ioctl(device, VFIO_DEVICE_RESET); +IOMMUFD and vfio_iommu_type1 +---------------------------- + +IOMMUFD is the new user API to manage I/O page tables from userspace. +It intends to be the portal of delivering advanced userspace DMA +features (nested translation [5]_, PASID [6]_, etc.) while also providing +a backwards compatibility interface for existing VFIO_TYPE1v2_IOMMU use +cases. Eventually the vfio_iommu_type1 driver, as well as the legacy +vfio container and group model is intended to be deprecated. + +The IOMMUFD backwards compatibility interface can be enabled two ways. +In the first method, the kernel can be configured with +CONFIG_IOMMUFD_VFIO_CONTAINER, in which case the IOMMUFD subsystem +transparently provides the entire infrastructure for the VFIO +container and IOMMU backend interfaces. The compatibility mode can +also be accessed if the VFIO container interface, ie. /dev/vfio/vfio is +simply symlink'd to /dev/iommu. Note that at the time of writing, the +compatibility mode is not entirely feature complete relative to +VFIO_TYPE1v2_IOMMU (ex. DMA mapping MMIO) and does not attempt to +provide compatibility to the VFIO_SPAPR_TCE_IOMMU interface. Therefore +it is not generally advisable at this time to switch from native VFIO +implementations to the IOMMUFD compatibility interfaces. + +Long term, VFIO users should migrate to device access through the cdev +interface described below, and native access through the IOMMUFD +provided interfaces. + +VFIO Device cdev +---------------- + +Traditionally user acquires a device fd via VFIO_GROUP_GET_DEVICE_FD +in a VFIO group. + +With CONFIG_VFIO_DEVICE_CDEV=y the user can now acquire a device fd +by directly opening a character device /dev/vfio/devices/vfioX where +"X" is the number allocated uniquely by VFIO for registered devices. +cdev interface does not support noiommu devices, so user should use +the legacy group interface if noiommu is wanted. + +The cdev only works with IOMMUFD. Both VFIO drivers and applications +must adapt to the new cdev security model which requires using +VFIO_DEVICE_BIND_IOMMUFD to claim DMA ownership before starting to +actually use the device. Once BIND succeeds then a VFIO device can +be fully accessed by the user. + +VFIO device cdev doesn't rely on VFIO group/container/iommu drivers. +Hence those modules can be fully compiled out in an environment +where no legacy VFIO application exists. + +So far SPAPR does not support IOMMUFD yet. So it cannot support device +cdev either. + +vfio device cdev access is still bound by IOMMU group semantics, ie. there +can be only one DMA owner for the group. Devices belonging to the same +group can not be bound to multiple iommufd_ctx or shared between native +kernel and vfio bus driver or other driver supporting the driver_managed_dma +flag. A violation of this ownership requirement will fail at the +VFIO_DEVICE_BIND_IOMMUFD ioctl, which gates full device access. + +Device cdev Example +------------------- + +Assume user wants to access PCI device 0000:6a:01.0:: + + $ ls /sys/bus/pci/devices/0000:6a:01.0/vfio-dev/ + vfio0 + +This device is therefore represented as vfio0. The user can verify +its existence:: + + $ ls -l /dev/vfio/devices/vfio0 + crw------- 1 root root 511, 0 Feb 16 01:22 /dev/vfio/devices/vfio0 + $ cat /sys/bus/pci/devices/0000:6a:01.0/vfio-dev/vfio0/dev + 511:0 + $ ls -l /dev/char/511\:0 + lrwxrwxrwx 1 root root 21 Feb 16 01:22 /dev/char/511:0 -> ../vfio/devices/vfio0 + +Then provide the user with access to the device if unprivileged +operation is desired:: + + $ chown user:user /dev/vfio/devices/vfio0 + +Finally the user could get cdev fd by:: + + cdev_fd = open("/dev/vfio/devices/vfio0", O_RDWR); + +An opened cdev_fd doesn't give the user any permission of accessing +the device except binding the cdev_fd to an iommufd. After that point +then the device is fully accessible including attaching it to an +IOMMUFD IOAS/HWPT to enable userspace DMA:: + + struct vfio_device_bind_iommufd bind = { + .argsz = sizeof(bind), + .flags = 0, + }; + struct iommu_ioas_alloc alloc_data = { + .size = sizeof(alloc_data), + .flags = 0, + }; + struct vfio_device_attach_iommufd_pt attach_data = { + .argsz = sizeof(attach_data), + .flags = 0, + }; + struct iommu_ioas_map map = { + .size = sizeof(map), + .flags = IOMMU_IOAS_MAP_READABLE | + IOMMU_IOAS_MAP_WRITEABLE | + IOMMU_IOAS_MAP_FIXED_IOVA, + .__reserved = 0, + }; + + iommufd = open("/dev/iommu", O_RDWR); + + bind.iommufd = iommufd; + ioctl(cdev_fd, VFIO_DEVICE_BIND_IOMMUFD, &bind); + + ioctl(iommufd, IOMMU_IOAS_ALLOC, &alloc_data); + attach_data.pt_id = alloc_data.out_ioas_id; + ioctl(cdev_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_data); + + /* Allocate some space and setup a DMA mapping */ + map.user_va = (int64_t)mmap(0, 1024 * 1024, PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); + map.iova = 0; /* 1MB starting at 0x0 from device view */ + map.length = 1024 * 1024; + map.ioas_id = alloc_data.out_ioas_id;; + + ioctl(iommufd, IOMMU_IOAS_MAP, &map); + + /* Other device operations as stated in "VFIO Usage Example" */ + VFIO User API ------------------------------------------------------------------------------- @@ -279,6 +410,7 @@ similar to a file operations structure:: struct iommufd_ctx *ictx, u32 *out_device_id); void (*unbind_iommufd)(struct vfio_device *vdev); int (*attach_ioas)(struct vfio_device *vdev, u32 *pt_id); + void (*detach_ioas)(struct vfio_device *vdev); int (*open_device)(struct vfio_device *vdev); void (*close_device)(struct vfio_device *vdev); ssize_t (*read)(struct vfio_device *vdev, char __user *buf, @@ -315,9 +447,10 @@ container_of(). - The [un]bind_iommufd callbacks are issued when the device is bound to and unbound from iommufd. - - The attach_ioas callback is issued when the device is attached to an - IOAS managed by the bound iommufd. The attached IOAS is automatically - detached when the device is unbound from iommufd. + - The [de]attach_ioas callback is issued when the device is attached to + and detached from an IOAS managed by the bound iommufd. However, the + attached IOAS can also be automatically detached when the device is + unbound from iommufd. - The read/write/mmap callbacks implement the device region access defined by the device's own VFIO_DEVICE_GET_REGION_INFO ioctl. @@ -564,3 +697,11 @@ This implementation has some specifics: \-0d.1 00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90) + +.. [5] Nested translation is an IOMMU feature which supports two stage + address translations. This improves the address translation efficiency + in IOMMU virtualization. + +.. [6] PASID stands for Process Address Space ID, introduced by PCI + Express. It is a prerequisite for Shared Virtual Addressing (SVA) + and Scalable I/O Virtualization (Scalable IOV). diff --git a/Documentation/networking/device_drivers/ethernet/amd/pds_vfio_pci.rst b/Documentation/networking/device_drivers/ethernet/amd/pds_vfio_pci.rst new file mode 100644 index 000000000000..7a6bc848a2b2 --- /dev/null +++ b/Documentation/networking/device_drivers/ethernet/amd/pds_vfio_pci.rst @@ -0,0 +1,79 @@ +.. SPDX-License-Identifier: GPL-2.0+ +.. note: can be edited and viewed with /usr/bin/formiko-vim + +========================================================== +PCI VFIO driver for the AMD/Pensando(R) DSC adapter family +========================================================== + +AMD/Pensando Linux VFIO PCI Device Driver +Copyright(c) 2023 Advanced Micro Devices, Inc. + +Overview +======== + +The ``pds-vfio-pci`` module is a PCI driver that supports Live Migration +capable Virtual Function (VF) devices in the DSC hardware. + +Using the device +================ + +The pds-vfio-pci device is enabled via multiple configuration steps and +depends on the ``pds_core`` driver to create and enable SR-IOV Virtual +Function devices. + +Shown below are the steps to bind the driver to a VF and also to the +associated auxiliary device created by the ``pds_core`` driver. This +example assumes the pds_core and pds-vfio-pci modules are already +loaded. + +.. code-block:: bash + :name: example-setup-script + + #!/bin/bash + + PF_BUS="0000:60" + PF_BDF="0000:60:00.0" + VF_BDF="0000:60:00.1" + + # Prevent non-vfio VF driver from probing the VF device + echo 0 > /sys/class/pci_bus/$PF_BUS/device/$PF_BDF/sriov_drivers_autoprobe + + # Create single VF for Live Migration via pds_core + echo 1 > /sys/bus/pci/drivers/pds_core/$PF_BDF/sriov_numvfs + + # Allow the VF to be bound to the pds-vfio-pci driver + echo "pds-vfio-pci" > /sys/class/pci_bus/$PF_BUS/device/$VF_BDF/driver_override + + # Bind the VF to the pds-vfio-pci driver + echo "$VF_BDF" > /sys/bus/pci/drivers/pds-vfio-pci/bind + +After performing the steps above, a file in /dev/vfio/<iommu_group> +should have been created. + + +Enabling the driver +=================== + +The driver is enabled via the standard kernel configuration system, +using the make command:: + + make oldconfig/menuconfig/etc. + +The driver is located in the menu structure at: + + -> Device Drivers + -> VFIO Non-Privileged userspace driver framework + -> VFIO support for PDS PCI devices + +Support +======= + +For general Linux networking support, please use the netdev mailing +list, which is monitored by Pensando personnel:: + + netdev@vger.kernel.org + +For more specific support needs, please use the Pensando driver support +email:: + + drivers@pensando.io diff --git a/Documentation/networking/device_drivers/ethernet/index.rst b/Documentation/networking/device_drivers/ethernet/index.rst index 94ecb67c0885..9827e816084b 100644 --- a/Documentation/networking/device_drivers/ethernet/index.rst +++ b/Documentation/networking/device_drivers/ethernet/index.rst @@ -16,6 +16,7 @@ Contents: altera/altera_tse amd/pds_core amd/pds_vdpa + amd/pds_vfio_pci aquantia/atlantic chelsio/cxgb cirrus/cs89x0 diff --git a/Documentation/virt/kvm/devices/vfio.rst b/Documentation/virt/kvm/devices/vfio.rst index 08b544212638..c549143bb891 100644 --- a/Documentation/virt/kvm/devices/vfio.rst +++ b/Documentation/virt/kvm/devices/vfio.rst @@ -9,22 +9,34 @@ Device types supported: - KVM_DEV_TYPE_VFIO Only one VFIO instance may be created per VM. The created device -tracks VFIO groups in use by the VM and features of those groups -important to the correctness and acceleration of the VM. As groups -are enabled and disabled for use by the VM, KVM should be updated -about their presence. When registered with KVM, a reference to the -VFIO-group is held by KVM. +tracks VFIO files (group or device) in use by the VM and features +of those groups/devices important to the correctness and acceleration +of the VM. As groups/devices are enabled and disabled for use by the +VM, KVM should be updated about their presence. When registered with +KVM, a reference to the VFIO file is held by KVM. Groups: - KVM_DEV_VFIO_GROUP - -KVM_DEV_VFIO_GROUP attributes: - KVM_DEV_VFIO_GROUP_ADD: Add a VFIO group to VFIO-KVM device tracking - kvm_device_attr.addr points to an int32_t file descriptor - for the VFIO group. - KVM_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking - kvm_device_attr.addr points to an int32_t file descriptor - for the VFIO group. + KVM_DEV_VFIO_FILE + alias: KVM_DEV_VFIO_GROUP + +KVM_DEV_VFIO_FILE attributes: + KVM_DEV_VFIO_FILE_ADD: Add a VFIO file (group/device) to VFIO-KVM device + tracking + + kvm_device_attr.addr points to an int32_t file descriptor for the + VFIO file. + + KVM_DEV_VFIO_FILE_DEL: Remove a VFIO file (group/device) from VFIO-KVM + device tracking + + kvm_device_attr.addr points to an int32_t file descriptor for the + VFIO file. + +KVM_DEV_VFIO_GROUP (legacy kvm device group restricted to the handling of VFIO group fd): + KVM_DEV_VFIO_GROUP_ADD: same as KVM_DEV_VFIO_FILE_ADD for group fd only + + KVM_DEV_VFIO_GROUP_DEL: same as KVM_DEV_VFIO_FILE_DEL for group fd only + KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table allocated by sPAPR KVM. kvm_device_attr.addr points to a struct:: @@ -40,7 +52,10 @@ KVM_DEV_VFIO_GROUP attributes: - @tablefd is a file descriptor for a TCE table allocated via KVM_CREATE_SPAPR_TCE. -The GROUP_ADD operation above should be invoked prior to accessing the +The FILE/GROUP_ADD operation above should be invoked prior to accessing the device file descriptor via VFIO_GROUP_GET_DEVICE_FD in order to support drivers which require a kvm pointer to be set in their .open_device() -callback. +callback. It is the same for device file descriptor via character device +open which gets device access via VFIO_DEVICE_BIND_IOMMUFD. For such file +descriptors, FILE_ADD should be invoked before VFIO_DEVICE_BIND_IOMMUFD +to support the drivers mentioned in prior sentence as well. |