1.. SPDX-License-Identifier: GPL-2.0 2 3=================== 4VFIO virtual device 5=================== 6 7Device types supported: 8 9 - KVM_DEV_TYPE_VFIO 10 11Only one VFIO instance may be created per VM. The created device 12tracks VFIO files (group or device) in use by the VM and features 13of those groups/devices important to the correctness and acceleration 14of the VM. As groups/devices are enabled and disabled for use by the 15VM, KVM should be updated about their presence. When registered with 16KVM, a reference to the VFIO file is held by KVM. 17 18Groups: 19 KVM_DEV_VFIO_FILE 20 alias: KVM_DEV_VFIO_GROUP 21 22KVM_DEV_VFIO_FILE attributes: 23 KVM_DEV_VFIO_FILE_ADD: Add a VFIO file (group/device) to VFIO-KVM device 24 tracking 25 26 kvm_device_attr.addr points to an int32_t file descriptor for the 27 VFIO file. 28 29 KVM_DEV_VFIO_FILE_DEL: Remove a VFIO file (group/device) from VFIO-KVM 30 device tracking 31 32 kvm_device_attr.addr points to an int32_t file descriptor for the 33 VFIO file. 34 35KVM_DEV_VFIO_GROUP (legacy kvm device group restricted to the handling of VFIO group fd): 36 KVM_DEV_VFIO_GROUP_ADD: same as KVM_DEV_VFIO_FILE_ADD for group fd only 37 38 KVM_DEV_VFIO_GROUP_DEL: same as KVM_DEV_VFIO_FILE_DEL for group fd only 39 40 KVM_DEV_VFIO_GROUP_SET_SPAPR_TCE: attaches a guest visible TCE table 41 allocated by sPAPR KVM. 42 kvm_device_attr.addr points to a struct:: 43 44 struct kvm_vfio_spapr_tce { 45 __s32 groupfd; 46 __s32 tablefd; 47 }; 48 49 where: 50 51 - @groupfd is a file descriptor for a VFIO group; 52 - @tablefd is a file descriptor for a TCE table allocated via 53 KVM_CREATE_SPAPR_TCE. 54 55The FILE/GROUP_ADD operation above should be invoked prior to accessing the 56device file descriptor via VFIO_GROUP_GET_DEVICE_FD in order to support 57drivers which require a kvm pointer to be set in their .open_device() 58callback. It is the same for device file descriptor via character device 59open which gets device access via VFIO_DEVICE_BIND_IOMMUFD. For such file 60descriptors, FILE_ADD should be invoked before VFIO_DEVICE_BIND_IOMMUFD 61to support the drivers mentioned in prior sentence as well. 62