POWER9 eXternal Interrupt Virtualization Engine (XIVE Gen1)
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Device types supported:
  KVM_DEV_TYPE_XIVE     POWER9 XIVE Interrupt Controller generation 1

This device acts as a VM interrupt controller. It provides the KVM
interface to configure the interrupt sources of a VM in the underlying
POWER9 XIVE interrupt controller.

Only one XIVE instance may be instantiated. A guest XIVE device
requires a POWER9 host and the guest OS should have support for the
XIVE native exploitation interrupt mode. If not, it should run using
the legacy interrupt mode, referred as XICS (POWER7/8).

* Groups:

  1. KVM_DEV_XIVE_GRP_CTRL
  Provides global controls on the device

  2. KVM_DEV_XIVE_GRP_SOURCE (write only)
  Initializes a new source in the XIVE device and mask it.
  Attributes:
    Interrupt source number  (64-bit)
  The kvm_device_attr.addr points to a __u64 value:
  bits:     | 63   ....  2 |   1   |   0
  values:   |    unused    | level | type
  - type:  0:MSI 1:LSI
  - level: assertion level in case of an LSI.
  Errors:
    -E2BIG:  Interrupt source number is out of range
    -ENOMEM: Could not create a new source block
    -EFAULT: Invalid user pointer for attr->addr.
    -ENXIO:  Could not allocate underlying HW interrupt