powerpc/64s/kuap: Restore AMR in system reset exception

The system reset interrupt handler locks AMR and exits with
EXCEPTION_RESTORE_REGS without restoring AMR. Similarly to the
soft-NMI handler, it needs to restore.

Fixes: 890274c ("powerpc/64s: Implement KUAP for Radix MMU")
Signed-off-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: npiggin

arch/powerpc/kernel/exceptions-64s.S

@@ -971,6 +971,7 @@ EXC_COMMON_BEGIN(system_reset_common)
 	ld	r10,SOFTE(r1)
 	stb	r10,PACAIRQSOFTMASK(r13)
 
+	kuap_restore_amr r10
 	EXCEPTION_RESTORE_REGS
 	RFI_TO_USER_OR_KERNEL