[Skiboot] [PATCH v2 1/2] mpipl: Delay MPIPL registration until OPAL init is complete

[Vasant Hegde]

If OPAL boot fails after MPIPL init (opal_mpipl_init()) then we call MPIPL
boot instead of reboot. BMC is not aware of MPIPL. Hence it may result in
continuous MPIPL loop (boot -> crash -> MPIPL -> boot).

If OPAL boot fails (before loading kernel) then its better to call reboot.
So that BMC can detect `n` number of boot failures (generally n = 3) and
stop booting. That way we can avoid continuous loop.

This patch moves MPIPL init to the end of init process (just before starting
kernel). So that if we fail to boot OPAL we call normal reboot.

Also this patch introduces new function to detect MPIPL is enabled or not
(is_mpipl_enabled()). And in assert() path we check for this function
instead of `dump` DT node. So that it will make sure we will not call
MPIPL until opal_mpipl_init is complete.

Signed-off-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
---
Changes in v2:
  - Moved mpipl_init just before checksum_romem(). Othesewise fast
    reboot fails.

-Vasant

 core/init.c         |  7 ++++---
 core/opal-dump.c    | 10 ++++++++++
 hw/sbe-p9.c         |  2 +-
 include/opal-dump.h |  3 +++
 4 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/core/init.c b/core/init.c
index 9f3b8c6fd..0a593cd1a 100644
--- a/core/init.c
+++ b/core/init.c
@@ -635,6 +635,10 @@ void __noreturn load_and_boot_kernel(bool is_reboot)
 	patch_traps(false);
 	cpu_set_hile_mode(false); /* Clear HILE on all CPUs */
 
+	/* init MPIPL */
+	if (!is_reboot)
+		opal_mpipl_init();
+
 	checksum_romem();
 
 	debug_descriptor.state_flags |= OPAL_BOOT_COMPLETE;
@@ -1363,9 +1367,6 @@ void __noreturn __nomcount main_cpu_entry(const void *fdt)
 	/* Create the LPC bus interrupt-map on P9 */
 	lpc_finalize_interrupts();
 
-	/* init opal dump */
-	opal_mpipl_init();
-
 	/* Add the list of interrupts going to OPAL */
 	add_opal_interrupts();
 
diff --git a/core/opal-dump.c b/core/opal-dump.c
index a31ecbe4d..ca6bf0648 100644
--- a/core/opal-dump.c
+++ b/core/opal-dump.c
@@ -67,6 +67,8 @@ static int opal_mpipl_max_tags = MAX_OPAL_MPIPL_TAGS;
 
 static u64 opal_dump_addr, opal_dump_size;
 
+static bool mpipl_enabled;
+
 static int opal_mpipl_add_entry(u8 region, u64 src, u64 dest, u64 size)
 {
 	int i;
@@ -526,6 +528,11 @@ void opal_mpipl_reserve_mem(void)
 		       arch_regs_dest, arch_regs_size);
 }
 
+bool is_mpipl_enabled(void)
+{
+	return mpipl_enabled;
+}
+
 void opal_mpipl_init(void)
 {
 	void *mdst_base = (void *)MDST_TABLE_BASE;
@@ -575,4 +582,7 @@ void opal_mpipl_init(void)
 	opal_register(OPAL_MPIPL_UPDATE, opal_mpipl_update, 4);
 	opal_register(OPAL_MPIPL_REGISTER_TAG, opal_mpipl_register_tag, 2);
 	opal_register(OPAL_MPIPL_QUERY_TAG, opal_mpipl_query_tag, 2);
+
+	/* Enable MPIPL */
+	mpipl_enabled = true;
 }
diff --git a/hw/sbe-p9.c b/hw/sbe-p9.c
index 18caa0a28..24ed91b93 100644
--- a/hw/sbe-p9.c
+++ b/hw/sbe-p9.c
@@ -949,7 +949,7 @@ void p9_sbe_terminate(void)
 	struct proc_chip *chip;
 
 	/* Return if MPIPL is not supported */
-	if (!dt_find_by_path(opal_node, "dump"))
+	if (!is_mpipl_enabled())
 		return;
 
 	/* Unregister flash. It will request BMC MBOX reset */
diff --git a/include/opal-dump.h b/include/opal-dump.h
index 060712e99..bc1b8768d 100644
--- a/include/opal-dump.h
+++ b/include/opal-dump.h
@@ -127,4 +127,7 @@ void opal_mpipl_save_crashing_pir(void);
 /* Reserve memory to capture OPAL dump */
 extern void opal_mpipl_reserve_mem(void);
 
+/* Check MPIPL enabled or not */
+extern bool is_mpipl_enabled(void);
+
 #endif	/* __OPAL_DUMP_H */
-- 
2.26.2