[PATCH] powerpc: align memory_limit to 16MB in early_parse_mem

From: Joel Savitz <jsavitz@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Gonzalo Siero <gsierohu@redhat.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Benjamin Gray <bgray@linux.ibm.com>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, Joel Savitz <jsavitz@redhat.com>
Subject: [PATCH] powerpc: align memory_limit to 16MB in early_parse_mem
Date: Fri,  1 Mar 2024 15:30:23 -0500	[thread overview]
Message-ID: <20240301203023.2197451-1-jsavitz@redhat.com> (raw)

On 64-bit powerpc, usage of a non-16MB-aligned value for the mem= kernel
cmdline parameter results in a system hang at boot.

For example, using 'mem=4198400K' will always reproduce this issue.

This patch fixes the problem by aligning any argument to mem= to 16MB
corresponding with the large page size on powerpc.

Fixes: 2babf5c2ec2f ("[PATCH] powerpc: Unify mem= handling")
Co-developed-by: Gonzalo Siero <gsierohu@redhat.com>
Signed-off-by: Gonzalo Siero <gsierohu@redhat.com>
Signed-off-by: Joel Savitz <jsavitz@redhat.com>
---
 arch/powerpc/kernel/prom.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 0b5878c3125b..8cd3e2445d8a 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -82,8 +82,12 @@ static int __init early_parse_mem(char *p)
 {
 	if (!p)
 		return 1;
-
+#ifdef CONFIG_PPC64
+	/* Align to 16 MB == size of ppc64 large page */
+	memory_limit = ALIGN(memparse(p, &p), 0x1000000);
+#else
 	memory_limit = PAGE_ALIGN(memparse(p, &p));
+#endif
 	DBG("memory limit = 0x%llx\n", memory_limit);
 
 	return 0;
-- 
2.43.0

