In the case of a crash/panic an architecture specific function
machine_crash_shutdown is called.  This patch adds to the x86 machine_crash
function the standard kernel code for shutting down apics.

Every line of code added to that function increases the risk that we will call
code after a kernel panic that is not safe.

This patch should not make it to the stable kernel without a being reviewed a
lot more.  It is unclear how much a hardned kernel can take when it comes to
misconfigured apics.  So since a normal kernel has problems this patch does a
clean shutdown.

It is my expectation this patch will be dropped from future generations of the
kexec work.  But for the moment it is a crutch to keep from breaking
everything.

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>