The USB-based tablet is often the only USB device in an x86 instance,
while the USB-based keyboard is often the only such device in an AArch64
instance (x86 have PS2 keyboards and mice). Replacing these with
virtio-based devices can eliminate the need to have a USB host adapter
in the instance. Enable just that possibility by adding a new value
image metadata property, 'hw_input_bus'. This allows us to specify not
only virtio-based pointer and keyboard input devices but also USB
equivalents.
Note that this also fixes one instance of a particular class of bugs,
whereby we have checks for *guest* architecture-specific behavior that
are being toggled based on the *host* architecture. In this instance,
we were attempting to add a keyboard device on AArch64 guests since they
don't have one by default, but we were determining the architecture by
looking at the CPU architecture reported in the host capabilities. By
replacing this check of the host capabilities with a call to the
'nova.virt.libvirt.utils.get_arch' helper, we correctly handle requests
to create non-host architecture guests via the 'hw_architecture' image
metadata property. There are many other instances of this bug and those
can be resolved separately.
Change-Id: If9f3ede3e8449f9a6c8d1da927974c0a73923d51
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
3f63c68195