[PATCH 09/15] x86: Emergency virtualization disable function

[Eduardo Habkost]

On Wed, Nov 05, 2008 at 11:27:32PM +0100, Pavel Machek wrote:
> On Wed 2008-11-05 17:56:52, Eduardo Habkost wrote:
> > This patch adds an interface to set a function that can be used to
> > disable virtualization extensions on the CPU on emergency cases, such
> > as on kdump or emergency reboot.
> > 
> > The function will be set by code that enables virtualization extensions
> > on the CPUs (i.e. KVM), and should do the very least to disable virt
> > extensions on the CPU where it is being called.
> > 
> > The functions that set the function pointer uses RCU synchronization,
> > just in case the crash NMI is triggered while KVM is unloading.
> > 
> > We can't just use the same notifiers used at reboot time (that are used
> > by non-crash-dump kexec), because at crash time some CPUs may have IRQs
> > disabled, so we can't use IPIs. The crash shutdown code use NMIs to tell
> > the other CPUs to be halted, so the notifier call will be hooked into
> > the CPU halting code that is on the crash shutdown NMI handler.
> > 
> > [v2: drop 'unsigned int cpu' arg from function]
> > [v3: make emergency_virt_disable() non-static]
> > [v4: add a config option for it: CPU_VIRT_EXTENSIONS]
> > [v5: add has_virt_extensions() function]
> > [v6: don't define the registering functions if CPU_VIRT_EXTENSIONS is
> >  not enabled]
> > [v7: use EXPORT_SYMBOL_GPL]
> > 
> 
> > --- /dev/null
> > +++ b/arch/x86/kernel/virtext.c
> > @@ -0,0 +1,89 @@
> > +/* Core CPU virtualization extensions handling
> > + *
> > + * This should carry the code for handling CPU virtualization extensions
> > + * that needs to live in the kernel core.
> > + *
> > + * Author: Eduardo Habkost <ehabkost at redhat.com>
> > + *
> > + * Copyright (C) 2008, Red Hat Inc.
> > + */
> 
> GPL?

Yes, of course.

As IANAL, I used a similar .c file as reference for the author/copyright
info header, and used arch/x86/kernel/crash.c, that doesn't refer to
the GPL also. I think I chose a bad example as reference.

arch/x86/kernel/crash.c even has "All rights reserved". Ouch.

-- 
Eduardo