Re: [PATCH v2 15/16] powernv/fadump: consider f/w load area

OPAL loads kernel & initrd at 512MB offset (256MB size), also exported
as ibm,opal/dump/fw-load-area. So, if boot memory size of FADump is
less than 768MB, kernel memory to be exported as '/proc/vmcore' would
be overwritten by f/w while loading kernel & initrd. To avoid such a
scenario, enforce a minimum boot memory size of 768MB on OPAL platform.

Also, skip using FADump if a newer F/W version loads kernel & initrd
above 768MB.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
---
 arch/powerpc/kernel/fadump-common.h          |   15 +++++++++++++--
 arch/powerpc/kernel/fadump.c                 |    8 ++++++++
 arch/powerpc/platforms/powernv/opal-fadump.c |   23 +++++++++++++++++++++++
 3 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/fadump-common.h b/arch/powerpc/kernel/fadump-common.h
index 1bd3aeb..f59fdc7 100644
--- a/arch/powerpc/kernel/fadump-common.h
+++ b/arch/powerpc/kernel/fadump-common.h

@@ -24,14 +24,25 @@
 #define RMA_END		(ppc64_rma_size)
 
 /*
+ * With kernel & initrd loaded at 512MB (with 256MB size), enforce a minimum
+ * boot memory size of 768MB to ensure f/w loading kernel and initrd doesn't
+ * mess with crash'ed kernel's memory during MPIPL.
+ */
+#define OPAL_MIN_BOOT_MEM	(0x30000000UL)
+
+/*
  * On some Power systems where RMO is 128MB, it still requires minimum of
  * 256MB for kernel to boot successfully. When kdump infrastructure is
  * configured to save vmcore over network, we run into OOM issue while
  * loading modules related to network setup. Hence we need additional 64M
  * of memory to avoid OOM issue.
  */
-#define MIN_BOOT_MEM	(((RMA_END < (0x1UL << 28)) ? (0x1UL << 28) : RMA_END) \
-			+ (0x1UL << 26))
+#define PSERIES_MIN_BOOT_MEM	(((RMA_END < (0x1UL << 28)) ? (0x1UL << 28) : \
+				 RMA_END) + (0x1UL << 26))
+
+#define MIN_BOOT_MEM	((fw_dump.fadump_platform ==			\
+			 FADUMP_PLATFORM_POWERNV) ? OPAL_MIN_BOOT_MEM :	\
+			 PSERIES_MIN_BOOT_MEM)

 
 /* The upper limit percentage for user specified boot memory size (25%) */
 #define MAX_BOOT_MEM_RATIO			4

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index ba26169..3c3adc2 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c

@@ -582,6 +582,14 @@ int __init fadump_reserve_mem(void)
 				ALIGN(fw_dump.boot_memory_size,
 							FADUMP_CMA_ALIGNMENT);
 #endif
+
+		if ((fw_dump.fadump_platform == FADUMP_PLATFORM_POWERNV) &&
+		    (fw_dump.boot_memory_size < OPAL_MIN_BOOT_MEM)) {