[S390] fix "mem=" handling in case of standby memory

Standby memory detected with the sclp interface gets always registered
with add_memory calls without considering the limitationt that the
"mem=" kernel paramater implies.
So fix this and only register standby memory that is below the specified
limit.
This fixes zfcpdump since it uses "mem=32M". In case there is appr.
2GB standby memory present all of usable memory would be used for the
struct pages needed for standby memory.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 14 insertions, 2 deletions

diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
index 2bd9faeb3919..e8bd6ac22c99 100644
--- a/arch/s390/include/asm/setup.h
+++ b/arch/s390/include/asm/setup.h
@@ -43,6 +43,8 @@ struct mem_chunk {
 
 extern struct mem_chunk memory_chunk[];
 extern unsigned long real_memory_size;
+extern int memory_end_set;
+extern unsigned long memory_end;
 
 void detect_memory_layout(struct mem_chunk chunk[]);
 
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index d825f4950e4e..c5cfb6185eac 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -82,7 +82,9 @@ char elf_platform[ELF_PLATFORM_SIZE];
 
 struct mem_chunk __initdata memory_chunk[MEMORY_CHUNKS];
 volatile int __cpu_logical_map[NR_CPUS]; /* logical cpu to cpu address */
-static unsigned long __initdata memory_end;
+
+int __initdata memory_end_set;
+unsigned long __initdata memory_end;
 
 /*
  * This is set up by the setup-routine at boot-time
@@ -281,6 +283,7 @@ void (*pm_power_off)(void) = machine_power_off;
 static int __init early_parse_mem(char *p)
 {
         memory_end = memparse(p, &p);
+        memory_end_set = 1;
         return 0;
 }
 early_param("mem", early_parse_mem);
@@ -508,8 +511,10 @@ static void __init setup_memory_end(void)
         int i;
 
 #if defined(CONFIG_ZFCPDUMP) || defined(CONFIG_ZFCPDUMP_MODULE)
-        if (ipl_info.type == IPL_TYPE_FCP_DUMP)
+        if (ipl_info.type == IPL_TYPE_FCP_DUMP) {
                 memory_end = ZFCPDUMP_HSA_SIZE;
+                memory_end_set = 1;
+        }
 #endif
         memory_size = 0;
         memory_end &= PAGE_MASK;
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index 506390496416..77ab6e34a100 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -19,6 +19,7 @@
 #include <linux/memory.h>
 #include <asm/chpid.h>
 #include <asm/sclp.h>
+#include <asm/setup.h>
 
 #include "sclp.h"
 
@@ -474,6 +475,10 @@ static void __init add_memory_merged(u16 rn)
                 goto skip_add;
         if (start + size > VMEM_MAX_PHYS)
                 size = VMEM_MAX_PHYS - start;
+        if (memory_end_set && (start >= memory_end))
+                goto skip_add;
+        if (memory_end_set && (start + size > memory_end))
+                size = memory_end - start;
         add_memory(0, start, size);
 skip_add:
         first_rn = rn;