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 <hbath...@linux.ibm.com>
---
 arch/powerpc/kernel/fadump-common.h          |   11 +---------
 arch/powerpc/kernel/fadump.c                 |   11 +++++++++-
 arch/powerpc/platforms/powernv/opal-fadump.c |   29 ++++++++++++++++++++++++++
 arch/powerpc/platforms/powernv/opal-fadump.h |    7 ++++++
 arch/powerpc/platforms/pseries/rtas-fadump.c |    6 +++++
 arch/powerpc/platforms/pseries/rtas-fadump.h |   11 ++++++++++
 6 files changed, 64 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/fadump-common.h 
b/arch/powerpc/kernel/fadump-common.h
index 5dbcefc..e758eb6 100644
--- a/arch/powerpc/kernel/fadump-common.h
+++ b/arch/powerpc/kernel/fadump-common.h
@@ -26,16 +26,6 @@
 #define RMA_START      0x0
 #define RMA_END                (ppc64_rma_size)
 
-/*
- * 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))
-
 /* The upper limit percentage for user specified boot memory size (25%) */
 #define MAX_BOOT_MEM_RATIO                     4
 
@@ -163,6 +153,7 @@ struct fadump_ops {
        ulong   (*init_fadump_mem_struct)(struct fw_dump *fadump_config);
        ulong   (*get_kernel_metadata_size)(void);
        int     (*setup_kernel_metadata)(struct fw_dump *fadump_config);
+       ulong   (*get_bootmem_min)(void);
        int     (*register_fadump)(struct fw_dump *fadump_config);
        int     (*unregister_fadump)(struct fw_dump *fadump_config);
        int     (*invalidate_fadump)(struct fw_dump *fadump_config);
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index bb6a63c..ffc9e3f 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -335,7 +335,8 @@ static inline unsigned long 
fadump_calculate_reserve_size(void)
        if (memory_limit && size > memory_limit)
                size = memory_limit;
 
-       return (size > MIN_BOOT_MEM ? size : MIN_BOOT_MEM);
+       return (size > fw_dump.ops->get_bootmem_min() ? size :
+               fw_dump.ops->get_bootmem_min());
 }
 
 /*
@@ -493,6 +494,14 @@ int __init fadump_reserve_mem(void)
                                ALIGN(fw_dump.boot_memory_size,
                                                        FADUMP_CMA_ALIGNMENT);
 #endif
+
+               if (fw_dump.boot_memory_size < fw_dump.ops->get_bootmem_min()) {
+                       pr_err("Can't enable fadump with boot memory size 
(0x%lx) less than 0x%lx\n",
+                              fw_dump.boot_memory_size,
+                              fw_dump.ops->get_bootmem_min());
+                       goto error_out;
+               }
+
                if (!fadump_get_boot_mem_regions()) {
                        pr_err("Too many holes in boot memory area to enable 
fadump\n");
                        goto error_out;
diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c 
b/arch/powerpc/platforms/powernv/opal-fadump.c
index 3ef212d..618186e 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.c
+++ b/arch/powerpc/platforms/powernv/opal-fadump.c
@@ -15,6 +15,7 @@
 
 #include <linux/string.h>
 #include <linux/seq_file.h>
+#include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/libfdt.h>
 #include <linux/mm.h>
@@ -241,6 +242,11 @@ static int opal_fadump_setup_kernel_metadata(struct 
fw_dump *fadump_conf)
        return err;
 }
 
+static ulong opal_fadump_get_bootmem_min(void)
+{
+       return OPAL_FADUMP_MIN_BOOT_MEM;
+}
+
 static int opal_fadump_register_fadump(struct fw_dump *fadump_conf)
 {
        int i, err = -EIO;
@@ -535,6 +541,7 @@ static struct fadump_ops opal_fadump_ops = {
        .init_fadump_mem_struct         = opal_fadump_init_mem_struct,
        .get_kernel_metadata_size       = opal_fadump_get_kernel_metadata_size,
        .setup_kernel_metadata          = opal_fadump_setup_kernel_metadata,
+       .get_bootmem_min                = opal_fadump_get_bootmem_min,
        .register_fadump                = opal_fadump_register_fadump,
        .unregister_fadump              = opal_fadump_unregister_fadump,
        .invalidate_fadump              = opal_fadump_invalidate_fadump,
@@ -547,6 +554,7 @@ int __init opal_fadump_dt_scan(struct fw_dump *fadump_conf, 
ulong node)
 {
        unsigned long dn;
        const __be32 *prop;
+       int i, len;
 
        /*
         * Check if Firmware-Assisted Dump is supported. if yes, check
@@ -563,6 +571,27 @@ int __init opal_fadump_dt_scan(struct fw_dump 
*fadump_conf, ulong node)
                return 1;
        }
 
+       prop = of_get_flat_dt_prop(dn, "fw-load-area", &len);
+       if (prop) {
+               /*
+                * Each f/w load area is an (address,size) pair,
+                * 2 cells each, totalling 4 cells per range.
+                */
+               for (i = 0; i < len / (sizeof(*prop) * 4); i++) {
+                       u64 base, end;
+
+                       base = of_read_number(prop + (i * 4) + 0, 2);
+                       end = base;
+                       end += of_read_number(prop + (i * 4) + 2, 2);
+                       if (end > OPAL_FADUMP_MIN_BOOT_MEM) {
+                               pr_err("F/W load area: 0x%llx-0x%llx\n",
+                                      base, end);
+                               pr_err("F/W version not supported!\n");
+                               return 1;
+                       }
+               }
+       }
+
        fadump_conf->ops                = &opal_fadump_ops;
        fadump_conf->fadump_platform    = FADUMP_PLATFORM_POWERNV;
        fadump_conf->fadump_supported   = 1;
diff --git a/arch/powerpc/platforms/powernv/opal-fadump.h 
b/arch/powerpc/platforms/powernv/opal-fadump.h
index c833725..f09b0ea 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.h
+++ b/arch/powerpc/platforms/powernv/opal-fadump.h
@@ -16,6 +16,13 @@
 #ifndef CONFIG_PRESERVE_FA_DUMP
 #include <asm/reg.h>
 
+/*
+ * 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_FADUMP_MIN_BOOT_MEM               (0x30000000UL)
+
 /* OPAL FADump structure format version */
 #define OPAL_FADUMP_VERSION                    0x1
 
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c 
b/arch/powerpc/platforms/pseries/rtas-fadump.c
index 4372fb3..7c44bd4 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -145,6 +145,11 @@ static int rtas_fadump_setup_kernel_metadata(struct 
fw_dump *fadump_conf)
        return 0;
 }
 
+static ulong rtas_fadump_get_bootmem_min(void)
+{
+       return RTAS_FADUMP_MIN_BOOT_MEM;
+}
+
 static int rtas_fadump_register_fadump(struct fw_dump *fadump_conf)
 {
        int rc, err = -EIO;
@@ -514,6 +519,7 @@ static struct fadump_ops rtas_fadump_ops = {
        .init_fadump_mem_struct         = rtas_fadump_init_mem_struct,
        .get_kernel_metadata_size       = rtas_fadump_get_kernel_metadata_size,
        .setup_kernel_metadata          = rtas_fadump_setup_kernel_metadata,
+       .get_bootmem_min                = rtas_fadump_get_bootmem_min,
        .register_fadump                = rtas_fadump_register_fadump,
        .unregister_fadump              = rtas_fadump_unregister_fadump,
        .invalidate_fadump              = rtas_fadump_invalidate_fadump,
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.h 
b/arch/powerpc/platforms/pseries/rtas-fadump.h
index 25da5b8..080e214 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.h
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.h
@@ -16,6 +16,17 @@
 #ifndef __PPC64_RTAS_FA_DUMP_H__
 #define __PPC64_RTAS_FA_DUMP_H__
 
+/*
+ * 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 RTAS_FADUMP_MIN_BOOT_MEM       (((RMA_END < (0x1UL << 28)) ?   \
+                                        (0x1UL << 28) : RMA_END) +     \
+                                        (0x1UL << 26))
+
 /* Firmware provided dump sections */
 #define RTAS_FADUMP_CPU_STATE_DATA     0x0001
 #define RTAS_FADUMP_HPTE_REGION                0x0002

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