This RFC adds a Xen-specific virtio-cpufreq device model so a guest
frontend can query the host pCPU frequency of the pCPU that currently
runs a given vCPU.

The guest protocol uses virtio device ID 42, which is not assigned by
the virtio specification or by Linux. Patch 1 defines that ID in
QEMU's imported virtio_ids.h. checkpatch warns that this file is
normally updated via scripts/update-linux-headers.sh; that script
cannot produce ID 42 until the ID exists upstream, so the define is
added by hand for this RFC.

The backend requires each vCPU to be pinned to a unique pCPU. The PCI
device uses two MSI-X vectors so virtio_notify() reaches the Android
frontend we tested against.

This is a port of an AMD qemu-xen device. A companion Linux guest
driver RFC was sent to linux-pm.

Based on work by Meng Zhang.

Baorui.Liu (3):
  standard-headers: add experimental VIRTIO_ID_CPUFREQ
  hw/virtio: add virtio-cpufreq Xen backend
  hw/virtio: give virtio-cpufreq two MSI-X vectors

 MAINTAINERS                                 |   7 +
 hw/virtio/Kconfig                           |   5 +
 hw/virtio/meson.build                       |   2 +
 hw/virtio/virtio-cpufreq-pci.c              |  88 +++++++
 hw/virtio/virtio-cpufreq.c                  | 242 ++++++++++++++++++++
 hw/virtio/virtio-pci.c                      |   3 +
 hw/virtio/virtio-qmp.c                      |   1 +
 hw/virtio/virtio.c                          |   1 +
 include/hw/virtio/virtio-cpufreq.h          |  23 ++
 include/standard-headers/linux/virtio_ids.h |   1 +
 10 files changed, 373 insertions(+)
 create mode 100644 hw/virtio/virtio-cpufreq-pci.c
 create mode 100644 hw/virtio/virtio-cpufreq.c
 create mode 100644 include/hw/virtio/virtio-cpufreq.h

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2.34.1