powerpc/powernv: Invoke opal_cec_reboot2() on unrecoverable machine check errors.
On non-recoverable MCE errors in kernel space, Linux kernel panics
and system reboots. On BMC based system opal-prd runs as a daemon
in the host. Hence, kernel crash may prevent opal-prd to detect and
analyze this MCE error. This may land us in a situation where the faulty
memory never gets de-configured and Linux would keep hitting same MCE error
again and again. If this happens in early stage of kernel initialization,
then Linux will keep crashing and rebooting in a loop.
This patch fixes this issue by invoking new opal_cec_reboot2() call with
reboot type OPAL_REBOOT_PLATFORM_ERROR to inform BMC/OCC about this
error, so that BMC can collect relevant data for error analysis and
decide what component to de-configure before rebooting.
This patch is dependent on OPAL patchset posted on skiboot mailing list
at https://lists.ozlabs.org/pipermail/skiboot/2015-July/001771.html that
introduces opal_cec_reboot2() opal call.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index f084afa..a2b53f2 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -441,6 +441,7 @@
int opal_machine_check(struct pt_regs *regs)
{
struct machine_check_event evt;
+ int ret;
if (!get_mce_event(&evt, MCE_EVENT_RELEASE))
return 0;
@@ -455,6 +456,40 @@
if (opal_recover_mce(regs, &evt))
return 1;
+
+ /*
+ * Unrecovered machine check, we are heading to panic path.
+ *
+ * We may have hit this MCE in very early stage of kernel
+ * initialization even before opal-prd has started running. If
+ * this is the case then this MCE error may go un-noticed or
+ * un-analyzed if we go down panic path. We need to inform
+ * BMC/OCC about this error so that they can collect relevant
+ * data for error analysis before rebooting.
+ * Use opal_cec_reboot2(OPAL_REBOOT_PLATFORM_ERROR) to do so.
+ * This function may not return on BMC based system.
+ */
+ ret = opal_cec_reboot2(OPAL_REBOOT_PLATFORM_ERROR,
+ "Unrecoverable Machine Check exception");
+ if (ret == OPAL_UNSUPPORTED) {
+ pr_emerg("Reboot type %d not supported\n",
+ OPAL_REBOOT_PLATFORM_ERROR);
+ }
+
+ /*
+ * We reached here. There can be three possibilities:
+ * 1. We are running on a firmware level that do not support
+ * opal_cec_reboot2()
+ * 2. We are running on a firmware level that do not support
+ * OPAL_REBOOT_PLATFORM_ERROR reboot type.
+ * 3. We are running on FSP based system that does not need opal
+ * to trigger checkstop explicitly for error analysis. The FSP
+ * PRD component would have already got notified about this
+ * error through other channels.
+ *
+ * In any case, let us just fall through. We anyway heading
+ * down to panic path.
+ */
return 0;
}