[Skiboot] [PATCH] IPMI: Trigger attention in abort path.

Mahesh Salgaonkar mahesh at linux.vnet.ibm.com
Thu Oct 24 03:20:45 AEDT 2019

OpenBMC is capable of catching attn instruction as TI and facilitate in
rebooting (IPL-ing) host while keeping a reboot counter. This functionality
was not present with other BMCs e.g. SMC and AMI. And hence OPAL never used
to trigger an attn during abort/assert path for BMC based system. Instead
it always triggered normal reboot during abort. This means that BMC never
gets notified about OPAL termination/reboot. This sometimes leads into
never ending IPL-ing loop if OPAL keeps aborting very early in boot path.
This can be avoided on OpenBMC system that supports handling of TI (attn

With AutoReboot policy, OpenBMC handles TIs (attn instruction) and counts
them against the reboot counter. In cases where OPAL is crashing before
host reaches to runtime, OpenBMC will move the system in Quiesced state
after 3 or so attempts of IPL/reboot so that system can be debugged.

This patch triggers an attn on OpenBMC system to inform BMC about the OPAL
termination. When system is moved to Quiesced state by BMC, it does not
makes sure that all CPU threads are also quiesced. Hence, make sure to
move all secondaries into quiesced state before calling attn.

Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
 hw/ipmi/ipmi-attn.c       |   32 ++++++++++++++++++++++++++------
 include/platform.h        |    1 +
 platforms/astbmc/common.c |    1 +
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/hw/ipmi/ipmi-attn.c b/hw/ipmi/ipmi-attn.c
index 3a615189d..4b5e9ca89 100644
--- a/hw/ipmi/ipmi-attn.c
+++ b/hw/ipmi/ipmi-attn.c
@@ -14,6 +14,7 @@
 #include <skiboot.h>
 #include <stack.h>
 #include <timebase.h>
+#include <direct-controls.h>
 /* Use same attention SRC for BMC based machine */
@@ -67,18 +68,37 @@ void __attribute__((noreturn)) ipmi_terminate(const char *msg)
-	/* Terminate called before initializing IPMI (early abort) */
-	if (!ipmi_present()) {
-		if (platform.cec_reboot)
-			platform.cec_reboot();
-		goto out;
+	/*
+	 * if BMC has attn support then let BMC know that we are terminating by
+	 * triggering attn so that BMC will decide whether to reboot/IPL or not
+	 * depending on AutoReboot policy.  This helps in cases where OPAL is
+	 * crashing/terminating before host reaches to runtime. With BMC
+	 * AutoReboot policy, in such cases, it will make sure that system is
+	 * moved to Quiesced state after 3 or so attempts to IPL. Without
+	 * `attn` call BMC will never know that OPAL is terminating and system
+	 * would go into never ending IPL'ing loop.
+	 *
+	 * When BMC moves the system into Quiesced state, it does not make sure
+	 * that all CPU threads are also quiesced. Hence, make sure to move all
+	 * secondaries into quiesced state before calling attn.
+	 *
+	 * Once the system reaches to runtime BMC resets the boot counter.
+	 * Hence next time when BMC receieves the attn it will IPL the system
+	 * if AutoReboot is enabled. We don't need to worry about self
+	 * rebooting
+	 */
+	if (platform.bmc->sw->attn_supported) {
+		/* Put everybody in stop/quiesce except myself. */
+		sreset_all_prepare();
+		trigger_attn();
+		for (;;) ;
 	/* Reboot call */
 	if (platform.cec_reboot)
 	while (1)
diff --git a/include/platform.h b/include/platform.h
index 0b043856b..1fdc07fb8 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -39,6 +39,7 @@ struct bmc_sw_config {
 	uint32_t ipmi_oem_partial_add_esel;
 	uint32_t ipmi_oem_pnor_access_status;
 	uint32_t ipmi_oem_hiomap_cmd;
+	uint32_t attn_supported;
 struct bmc_platform {
diff --git a/platforms/astbmc/common.c b/platforms/astbmc/common.c
index 15ac231fb..0a1cc86b0 100644
--- a/platforms/astbmc/common.c
+++ b/platforms/astbmc/common.c
@@ -512,6 +512,7 @@ const struct bmc_sw_config bmc_sw_ami = {
 const struct bmc_sw_config bmc_sw_openbmc = {
 	.ipmi_oem_partial_add_esel   = IPMI_CODE(0x3a, 0xf0),
 	.ipmi_oem_hiomap_cmd         = IPMI_CODE(0x3a, 0x5a),
+	.attn_supported              = 1,
 /* Extracted from a Palmetto */

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