ipmi: flush the ipmi message queue before booting a kernel

Bring ipmi to a consistent state before booting a kernel by flushing
all outstanding messages. The OS may not start kicking the IPMI state
machine for some time.

For example, without this change, when booting in QEMU, the IPMI command
issued by ipmi_wdt_final_reset() to disable the watchdog is not sent to
the BMC before the OS boots, effectively leaving the watchdog enabled
until the OS begins to drive OPAL pollers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Stewart Smith <stewart@flamingspork.com>
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>

6 files changed, 44 insertions, 5 deletions

diff --git a/core/ipmi.c b/core/ipmi.c
index 59aa95f..673aa0c 100644
--- a/core/ipmi.c
+++ b/core/ipmi.c
@@ -159,7 +159,7 @@ void ipmi_cmd_done(uint8_t cmd, uint8_t netfn, uint8_t cc, struct ipmi_msg *msg)
 
 void ipmi_queue_msg_sync(struct ipmi_msg *msg)
 {
-	void (*poll)(void) = msg->backend->poll;
+	bool (*poll)(void) = msg->backend->poll;
 
 	if (!ipmi_present())
 		return;
@@ -192,6 +192,15 @@ void ipmi_queue_msg_sync(struct ipmi_msg *msg)
 	}
 }
 
+void ipmi_flush(void)
+{
+	if (!ipmi_present())
+		return;
+
+	while (ipmi_backend->poll())
+		time_wait_ms(10);
+}
+
 static void ipmi_read_event_complete(struct ipmi_msg *msg)
 {
 	prlog(PR_DEBUG, "IPMI read event %02x complete: %d bytes. cc: %02x\n",
diff --git a/hw/bt.c b/hw/bt.c
index 5016fea..1912cd3 100644
--- a/hw/bt.c
+++ b/hw/bt.c
@@ -519,9 +519,14 @@ static void bt_poll(struct timer *t __unused, void *data __unused,
 		       bt.irq_ok ? TIMER_POLL : msecs_to_tb(BT_DEFAULT_POLL_MS));
 }
 
-static void bt_ipmi_poll(void)
+static bool bt_ipmi_poll(void)
 {
+	if (!lpc_ok())
+		return false;
+
 	bt_poll(NULL, NULL, mftb());
+
+	return bt.queue_len > 0;
 }
 
 static void bt_add_msg(struct bt_msg *bt_msg)
diff --git a/hw/fsp/fsp-ipmi.c b/hw/fsp/fsp-ipmi.c
index e368c28..9e600f3 100644
--- a/hw/fsp/fsp-ipmi.c
+++ b/hw/fsp/fsp-ipmi.c
@@ -243,14 +243,22 @@ static int fsp_ipmi_dequeue_msg(struct ipmi_msg *ipmi_msg)
 	return 0;
 }
 
+
+static bool fsp_ipmi_poll(void)
+{
+	/* fsp_opal_poll poller checks command responses */
+	opal_run_pollers();
+
+	return !list_empty(&fsp_ipmi.msg_queue);
+}
+
 static struct ipmi_backend fsp_ipmi_backend = {
 	.alloc_msg	= fsp_ipmi_alloc_msg,
 	.free_msg	= fsp_ipmi_free_msg,
 	.queue_msg	= fsp_ipmi_queue_msg,
 	.queue_msg_head	= fsp_ipmi_queue_msg_head,
 	.dequeue_msg	= fsp_ipmi_dequeue_msg,
-	/* FIXME if ever use ipmi_queue_msg_sync on FSP */
-	.poll           = NULL,
+	.poll           = fsp_ipmi_poll,
 };
 
 static bool fsp_ipmi_rr_notify(uint32_t cmd_sub_mod,
diff --git a/include/ipmi.h b/include/ipmi.h
index 3e629ba..5b7efd1 100644
--- a/include/ipmi.h
+++ b/include/ipmi.h
@@ -178,8 +178,10 @@ struct ipmi_backend {
 	 *
 	 * So, ensure we have a way to drive any state machines that an IPMI
 	 * backend may neeed to crank to ensure forward progress.
+	 *
+	 * This returns true while there are any messages queued.
 	 */
-	void (*poll)(void);
+	bool (*poll)(void);
 };
 
 extern struct ipmi_backend *ipmi_backend;
@@ -220,6 +222,9 @@ void ipmi_queue_msg_sync(struct ipmi_msg *msg);
 /* Removes the message from the list, queued previously */
 int ipmi_dequeue_msg(struct ipmi_msg *msg);
 
+/* Polls the backend until all queued messages are completed */
+void ipmi_flush(void);
+
 /* Process a completed message */
 void ipmi_cmd_done(uint8_t cmd, uint8_t netfn, uint8_t cc, struct ipmi_msg *msg);
 
diff --git a/platforms/astbmc/common.c b/platforms/astbmc/common.c
index 9ce22b3..bfbba2d 100644
--- a/platforms/astbmc/common.c
+++ b/platforms/astbmc/common.c
@@ -504,6 +504,12 @@ void astbmc_exit(void)
 	ipmi_wdt_final_reset();
 
 	ipmi_set_boot_count();
+
+	/*
+	 * Booting into an OS that may not call back into skiboot for
+	 * some time. Ensure all IPMI messages are processed first.
+	 */
+	ipmi_flush();
 }
 
 static const struct bmc_sw_config bmc_sw_ami = {
diff --git a/platforms/ibm-fsp/common.c b/platforms/ibm-fsp/common.c
index 4a723b2..f289d1f 100644
--- a/platforms/ibm-fsp/common.c
+++ b/platforms/ibm-fsp/common.c
@@ -186,6 +186,12 @@ void ibm_fsp_exit(void)
 
 	/* Clear SRCs on the op-panel when Linux starts */
 	op_panel_clear_src();
+
+	/*
+	 * Booting into an OS that may not call back into skiboot for
+	 * some time. Ensure all IPMI messages are processed first.
+	 */
+	ipmi_flush();
 }
 
 int64_t ibm_fsp_cec_reboot(void)