[Skiboot] [PATCH 09/16] core/fast-reboot: improve NMI handling during fast reset
npiggin at gmail.com
Tue Jan 8 01:04:21 AEDT 2019
Improve sreset and MCE handling in fast reboot. Switch the HILE bit
off before copying OPAL's exception vectors, so NMIs can be handled
properly. Also disable MSR[ME] while the vectors are being overwritten.
Some of the remaining problem cases are documented in comments.
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
core/fast-reboot.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/core/fast-reboot.c b/core/fast-reboot.c
index 02ef84646..eb1b348ae 100644
@@ -170,8 +170,42 @@ void fast_reboot(void)
cpu->save_r1 = 0;
+ * Move SPRs and exception vectors back to OPAL-mode while all
+ * others are quiesced. MSR[ME] is disabled while these are switched,
+ * but system reset can not be blocked -- in theory an sreset coming
+ * from the BMC or SPE could crash here.
+ * Primarily we want to fix up the HID bits here to allow the OPAL
+ * exception handlers to work. Machine check would be the important
+ * one.
+ * This is one case where a thread other than thread0 of the core
+ * may update the shared SPRs. All other threads are stopped, so
+ * there should be no races.
/* Restore skiboot vectors */
+ * Secondaries may still have an issue with machine checks if they have
+ * HILE set because the machine check exception does not FIXUP_ENDIAN.
+ * Adding that would trash CFAR however. So we have a window where
+ * if a secondary takes an interrupt before the HILE is fixed, it will
+ * crash.
+ * sreset vector has a FIXUP_ENDIAN sequence at the start, so
+ * secondaries can cope.
/* Send everyone else to 0x100 */
More information about the Skiboot