powerpc/64s/exception: machine check use correct cfar for late handler

[ Upstream commit 0b66370c61fcf5fcc1d6901013e110284da6e2bb ]

Bare metal machine checks run an "early" handler in real mode before
running the main handler which reports the event.

The main handler runs exactly as a normal interrupt handler, after the
"windup" which sets registers back as they were at interrupt entry.
CFAR does not get restored by the windup code, so that will be wrong
when the handler is run.

Restore the CFAR to the saved value before running the late handler.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802105709.27696-8-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 92474227262b499cd4682aa425aa5617c546ca64..0c8b966e807022639504dab55f921ce49f14fab7 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -467,6 +467,10 @@ EXC_COMMON_BEGIN(machine_check_handle_early)
        RFI_TO_USER_OR_KERNEL
 9:
        /* Deliver the machine check to host kernel in V mode. */
+BEGIN_FTR_SECTION
+       ld      r10,ORIG_GPR3(r1)
+       mtspr   SPRN_CFAR,r10
+END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
        MACHINE_CHECK_HANDLER_WINDUP
        b       machine_check_pSeries