powerpc/kexec: Fix kexec/kdump in P9 guest kernels

[Michael Ellerman]

On Fri, 2017-11-24 at 03:51:02 UTC, Michael Ellerman wrote:
> The code that cleans up the IAMR/AMOR before kexec'ing failed to
> remember that when we're running as a guest AMOR is not writable, it's
> hypervisor privileged.
> 
> They symptom is that the kexec stops before entering purgatory and
> nothing else is seen on the console. If you examine the state of the
> system all threads will be in the 0x700 program check handler.
> 
> Fix it by making the write to AMOR dependent on HV mode.
> 
> Fixes: 1e2a516e89fc ("powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR")
> Cc: stable at vger.kernel.org # v4.10+
> Reported-by: Yilin Zhang <yilzhang at redhat.com>
> Debugged-by: David Gibson <david at gibson.dropbear.id.au>
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> Acked-by: Balbir Singh <bsingharora at gmail.com>
> Reviewed-by: David Gibson <david at gibson.dropbear.id.au>
> Tested-by: David Gibson <david at gibson.dropbear.id.au>

Applied to powerpc fixes.

https://git.kernel.org/powerpc/c/2621e945fbf1d6df5f3f0ba7be5bae

cheers