powerpc/fadump: reset metadata address during clean up

During kexec boot, metadata address needs to be reset to avoid running
into errors interpreting stale metadata address, in case the kexec'ed
kernel crashes before metadata address could be setup again.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821346629.5656.10783321582005237813.stgit@hbathini.in.ibm.com

arch/powerpc/include/asm/fadump-internal.h

@@ -117,6 +117,7 @@ struct fadump_ops {
 	int	(*fadump_register)(struct fw_dump *fadump_conf);
 	int	(*fadump_unregister)(struct fw_dump *fadump_conf);
 	int	(*fadump_invalidate)(struct fw_dump *fadump_conf);
+	void	(*fadump_cleanup)(struct fw_dump *fadump_conf);
 	int	(*fadump_process)(struct fw_dump *fadump_conf);
 	void	(*fadump_region_show)(struct fw_dump *fadump_conf,
 				      struct seq_file *m);

arch/powerpc/kernel/fadump.c

@@ -965,6 +965,9 @@ static int register_fadump(void)
 
 void fadump_cleanup(void)
 {
+	if (!fw_dump.fadump_supported)
+		return;
+
 	/* Invalidate the registration only if dump is active. */
 	if (fw_dump.dump_active) {
 		pr_debug("Invalidating firmware-assisted dump registration\n");
@@ -974,6 +977,9 @@ void fadump_cleanup(void)
 		fw_dump.ops->fadump_unregister(&fw_dump);
 		free_crash_memory_ranges();
 	}
+
+	if (fw_dump.ops->fadump_cleanup)
+		fw_dump.ops->fadump_cleanup(&fw_dump);
 }
 
 static void fadump_free_reserved_memory(unsigned long start_pfn,

arch/powerpc/platforms/powernv/opal-fadump.c

@@ -105,6 +105,15 @@ static int opal_fadump_invalidate(struct fw_dump *fadump_conf)
 	return -EIO;
 }
 
+static void opal_fadump_cleanup(struct fw_dump *fadump_conf)
+{
+	s64 ret;
+
+	ret = opal_mpipl_register_tag(OPAL_MPIPL_TAG_KERNEL, 0);
+	if (ret != OPAL_SUCCESS)
+		pr_warn("Could not reset (%llu) kernel metadata tag!\n", ret);
+}
+
 static int __init opal_fadump_process(struct fw_dump *fadump_conf)
 {
 	return -EINVAL;
@@ -145,6 +154,7 @@ static struct fadump_ops opal_fadump_ops = {
 	.fadump_register		= opal_fadump_register,
 	.fadump_unregister		= opal_fadump_unregister,
 	.fadump_invalidate		= opal_fadump_invalidate,
+	.fadump_cleanup			= opal_fadump_cleanup,
 	.fadump_process			= opal_fadump_process,
 	.fadump_region_show		= opal_fadump_region_show,
 	.fadump_trigger			= opal_fadump_trigger,