seccomp: whitelist syscalls fallocate(), fadvise64(), inotify_init1() and inotify_add_watch()

fallocate() is needed for snapshotting. If it isn’t whitelisted

    $ qemu-img create -f qcow2 x.qcow 1G
    Formatting 'x.qcow', fmt=qcow2 size=1073741824 encryption=off cluster_size=65536 lazy_refcounts=off
    $ qemu-kvm -display none -monitor stdio -sandbox on x.qcow
    QEMU 2.1.50 monitor - type 'help' for more information
    (qemu) savevm foo
    (qemu) loadvm foo

will fail, as will subsequent savevm commands on the same image.

fadvise64(), inotify_init1(), inotify_add_watch() are needed by
the SDL display. Without the whitelist entries,

    qemu-kvm -sandbox on

fails immediately.

In my tests fadvise64() is called 50--51 times per VM run. That
number seems independent of the duration of the run. fallocate(),
inotify_init1(), inotify_add_watch() are called once each.
Accordingly, they are added to the whitelist at a very low
priority.

Signed-off-by: Philipp Gesang <philipp.gesang@intra2net.com>
Signed-off-by: Eduardo Otubo <eduardo.otubo@profitbricks.com>
seccomp: change configure to avoid arm 32 to break

Current stable version of libseccomp (2.1.1) only supports i386 and
x86_64 archs correctly. This patch limits the usage of the syscall
filter for those archs and updates to the correct last version of
libseccomp.

This patch also fixes the bug:
https://bugs.launchpad.net/qemu/+bug/1363641

Signed-off-by: Eduardo Otubo <eduardo.otubo@profitbricks.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Paul Moore <pmoore@redhat.com>