linux_dsm_epyc7002/Documentation/virtual/kvm/devices/vfio.txt
Alex Williamson ec53500fae kvm: Add VFIO device
So far we've succeeded at making KVM and VFIO mostly unaware of each
other, but areas are cropping up where a connection beyond eventfds
and irqfds needs to be made.  This patch introduces a KVM-VFIO device
that is meant to be a gateway for such interaction.  The user creates
the device and can add and remove VFIO groups to it via file
descriptors.  When a group is added, KVM verifies the group is valid
and gets a reference to it via the VFIO external user interface.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2013-10-30 19:02:03 +01:00

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VFIO virtual device
===================
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.
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_DEV_VFIO_GROUP_DEL: Remove a VFIO group from VFIO-KVM device tracking
For each, kvm_device_attr.addr points to an int32_t file descriptor
for the VFIO group.