[PATCH 7/8] arm64/kexec: Add checks for KVM

[geoff@infradead.org (Geoff Levand)]

Hi Mark,

On Mon, 2015-01-26 at 19:19 +0000, Mark Rutland wrote:
> On Sat, Jan 17, 2015 at 12:23:34AM +0000, Geoff Levand wrote:
> > Add runtime checks that fail the arm64 kexec syscall for situations that would
> > result in system instability do to problems in the KVM kernel support.
> > These checks should be removed when the KVM problems are resolved fixed.
> > 
> > Signed-off-by: Geoff Levand <geoff@infradead.org>
> > ---
> >  arch/arm64/kernel/machine_kexec.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> > index 3d84759..a36459d 100644
> > --- a/arch/arm64/kernel/machine_kexec.c
> > +++ b/arch/arm64/kernel/machine_kexec.c
> > @@ -16,6 +16,9 @@
> >  #include <asm/cacheflush.h>
> >  #include <asm/system_misc.h>
> >  
> > +/* TODO: Remove this include when KVM can support a kexec reboot. */
> > +#include <asm/virt.h>
> > +
> >  /* Global variables for the relocate_kernel routine. */
> >  extern const unsigned char relocate_new_kernel[];
> >  extern const unsigned long relocate_new_kernel_size;
> > @@ -100,6 +103,13 @@ int machine_kexec_prepare(struct kimage *image)
> >  
> >  	kexec_image_info(image);
> >  
> > +	/* TODO: Remove this message when KVM can support a kexec reboot. */
> > +	if (IS_ENABLED(CONFIG_KVM) && is_hyp_mode_available()) {
> > +		pr_err("%s: Your kernel is configured with KVM support (CONFIG_KVM=y) which currently does not allow for kexec re-boot.\n",
> > +			__func__);
> > +		return -ENOSYS;
> > +	}
> 
> If you really don't want to implement KVM teardown, surely this should
> be at the start of the series, so we don't have a point in the middle
> where things may explode in this case?

Yes, you're right.  I'm hoping we can get the KVM fix done soon so this
is not needed.

-Geoff