cpu: Cleanup AMR and IAMR when re-initializing CPUs

There's a bug in current Linux kernels leaving crap in those registers
accross kexec and not sanitizing them on boot. This breaks kexec under
some circumstances (such as booting a hash kernel from a radix one
on P9 DD2.0).

The long term fix is in Linux, but this workaround is a reasonable
way of "sanitizing" those SPRs when Linux calls opal_reinit_cpus()
and shouldn't have adverse effects.

We could also use that same mechanism to cleanup other things as
well such as restoring some other SPRs to their default value in
the future.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/processor.h b/include/processor.h
index af3fd2b..2e1ac37 100644
--- a/include/processor.h
+++ b/include/processor.h
@@ -51,6 +51,8 @@
 #define SPR_SRR0	0x01a	/* RW: Exception save/restore reg 0 */
 #define SPR_SRR1	0x01b	/* RW: Exception save/restore reg 1 */
 #define SPR_CFAR	0x01c	/* RW: Come From Address Register */
+#define SPR_AMR		0x01d	/* RW: Authority Mask Register */
+#define SPR_IAMR	0x03d	/* RW: Instruction Authority Mask Register */
 #define SPR_RPR		0x0ba   /* RW: Relative Priority Register */
 #define SPR_TBRL	0x10c	/* RO: Timebase low */
 #define SPR_TBRU	0x10d	/* RO: Timebase high */