On Wed, Feb 03, 2016 at 06:00:16PM +0000, Marc Zyngier wrote:

Having both VHE and non-VHE capable CPUs in the same system
is likely to be a recipe for disaster.

If the boot CPU has VHE, but a secondary is not, we won't be
able to downgrade and run the kernel at EL1. Add CPU hotplug
to the mix, and this produces a terrifying mess.

Let's solve the problem once and for all. If you mix VHE and
non-VHE CPUs in the same system, you deserve to loose, and this
patch makes sure you don't get a chance.

This is implemented by storing the kernel execution level in
a global variable. Secondaries will park themselves in a
WFI loop if they observe a mismatch. Also, the primary CPU
will detect that the secondary CPU has died on a mismatched
execution level. Panic will follow.

Signed-off-by: Marc Zyngier <redacted>

Reviewed-by: Christoffer Dall <redacted>