From 1ad796e8c79747b225a6fdf930907c0977194261 Mon Sep 17 00:00:00 2001
From: Hari Bathini <hbathini@linux.ibm.com>
Date: Mon, 12 Sep 2022 12:20:31 +0530
Subject: [PATCH] ppc64/kdump: Limit kdump base to 512MB
References: bsc#1203410 ltc#199904
Patch-mainline: Submitted https://lore.kernel.org/linuxppc-dev/20220912065031.57416-1-hbathini@linux.ibm.com/
Since commit e641eb03ab2b0 ("powerpc: Fix up the kdump base cap to
128M") memory for kdump kernel has been reserved at an offset of
128MB. This held up well for a long time before running into boot
failure on LPARs having a lot of cores. Commit 7c5ed82b800d8
("powerpc: Set crashkernel offset to mid of RMA region") fixed this
boot failure by moving the offset to mid of RMA region. This change
meant the offset is either 256MB or 512MB on LPARs as ppc64_rma_size
was 512MB or 1024MB owing to commit 103a8542cb35b ("powerpc/book3s64/
radix: Fix boot failure with large amount of guest memory")
But ppc64_rma_size can be larger as well with newer f/w. So, limit
crashkernel reservation offset to 512MB to avoid running into boot
failures during kdump kernel boot, due to RTAS or other allocation
restrictions.
Also, while here, use SZ_128M instead of opening coding it.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kexec/core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kexec/core.c b/arch/powerpc/kexec/core.c
index ddac5217bb5d..b3f47ee75086 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -146,7 +146,7 @@ void __init reserve_crashkernel(void)
#ifdef CONFIG_PPC64
/*
* On the LPAR platform place the crash kernel to mid of
- * RMA size (512MB or more) to ensure the crash kernel
+ * RMA size (max. of 512MB) to ensure the crash kernel
* gets enough space to place itself and some stack to be
* in the first segment. At the same time normal kernel
* also get enough space to allocate memory for essential
@@ -154,9 +154,9 @@ void __init reserve_crashkernel(void)
* kernel starts at 128MB offset on other platforms.
*/
if (firmware_has_feature(FW_FEATURE_LPAR))
- crashk_res.start = ppc64_rma_size / 2;
+ crashk_res.start = min_t(u64, ppc64_rma_size / 2, SZ_512M);
else
- crashk_res.start = min(0x8000000ULL, (ppc64_rma_size / 2));
+ crashk_res.start = min_t(u64, ppc64_rma_size / 2, SZ_128M);
#else
crashk_res.start = KDUMP_KERNELBASE;
#endif
--
2.35.3