tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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.