core: Add support for per-CPU statistics

Record VM exits on a per-CPU basis and export this information via the
"CPU Get Info" hypercall.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
driver: Export cell statistics via sysfs

Provide an accumulation of per-CPU statistics for each cell via sysfs.
This can help analyzing potential performance issues of Jailhouse cells.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
tools: Prepare further command line tool extensions

Allow to add more extension scripts to the command line tool. We define
a structure that describes an extension by command / subcommand and
provides help to be displayed by the tool. The extension script itself
has to be called jailhouse-<command>-<subcommand>. We look for it in
$PATH, extended by the tool's directory and /usr/lib/jailhouse.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
tools: Add cell statistics viewer

Add a tool extension to view cell statistics via a basic curses-based
user interface.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>