From: Martin Schwidefsky <schwidefsky@de.ibm.com>

An arbitrary guest must not be allowed to trigger cmm actions.  Only one
specific guest namely the one that serves as the resource monitor may send cmm
messages.  Add a parameter that allows to specify the guest that may send
messages.  z/VMs resource manager has the name 'VMRMSVM' which is the default.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 arch/s390/mm/cmm.c          |    9 ++++++++-
 drivers/s390/net/smsgiucv.c |   19 ++++++++++++++-----
 drivers/s390/net/smsgiucv.h |    4 ++--
 3 files changed, 24 insertions(+), 8 deletions(-)

diff -puN arch/s390/mm/cmm.c~s390-cmm-guest-sender-id arch/s390/mm/cmm.c
--- 25/arch/s390/mm/cmm.c~s390-cmm-guest-sender-id	2005-04-26 03:41:07.034488920 -0700
+++ 25-akpm/arch/s390/mm/cmm.c	2005-04-26 03:41:07.040488008 -0700
@@ -20,6 +20,11 @@
 #include <asm/pgalloc.h>
 #include <asm/uaccess.h>
 
+static char *sender = "VMRMSVM";
+module_param(sender, charp, 0);
+MODULE_PARM_DESC(sender,
+		 "Guest name that may send SMSG messages (default VMRMSVM)");
+
 #include "../../../drivers/s390/net/smsgiucv.h"
 
 #define CMM_NR_PAGES ((PAGE_SIZE / sizeof(unsigned long)) - 2)
@@ -367,10 +372,12 @@ static struct ctl_table cmm_dir_table[] 
 #ifdef CONFIG_CMM_IUCV
 #define SMSG_PREFIX "CMM"
 static void
-cmm_smsg_target(char *msg)
+cmm_smsg_target(char *from, char *msg)
 {
 	long pages, seconds;
 
+	if (strlen(sender) > 0 && strcmp(from, sender) != 0)
+		return;
 	if (!cmm_skip_blanks(msg + strlen(SMSG_PREFIX), &msg))
 		return;
 	if (strncmp(msg, "SHRINK", 6) == 0) {
diff -puN drivers/s390/net/smsgiucv.c~s390-cmm-guest-sender-id drivers/s390/net/smsgiucv.c
--- 25/drivers/s390/net/smsgiucv.c~s390-cmm-guest-sender-id	2005-04-26 03:41:07.035488768 -0700
+++ 25-akpm/drivers/s390/net/smsgiucv.c	2005-04-26 03:41:07.041487856 -0700
@@ -32,7 +32,7 @@ struct smsg_callback {
 	struct list_head list;
 	char *prefix;
 	int len;
-	void (*callback)(char *str);
+	void (*callback)(char *from, char *str);
 };
 
 MODULE_AUTHOR
@@ -55,8 +55,9 @@ smsg_message_pending(iucv_MessagePending
 {
 	struct smsg_callback *cb;
 	unsigned char *msg;
+	unsigned char sender[9];
 	unsigned short len;
-	int rc;
+	int rc, i;
 
 	len = eib->ln1msg2.ipbfln1f;
 	msg = kmalloc(len + 1, GFP_ATOMIC|GFP_DMA);
@@ -69,10 +70,18 @@ smsg_message_pending(iucv_MessagePending
 	if (rc == 0) {
 		msg[len] = 0;
 		EBCASC(msg, len);
+		memcpy(sender, msg, 8);
+		sender[8] = 0;
+		/* Remove trailing whitespace from the sender name. */
+		for (i = 7; i >= 0; i--) {
+			if (sender[i] != ' ' && sender[i] != '\t')
+				break;
+			sender[i] = 0;
+		}
 		spin_lock(&smsg_list_lock);
 		list_for_each_entry(cb, &smsg_list, list)
 			if (strncmp(msg + 8, cb->prefix, cb->len) == 0) {
-				cb->callback(msg + 8);
+				cb->callback(sender, msg + 8);
 				break;
 			}
 		spin_unlock(&smsg_list_lock);
@@ -91,7 +100,7 @@ static struct device_driver smsg_driver 
 };
 
 int
-smsg_register_callback(char *prefix, void (*callback)(char *str))
+smsg_register_callback(char *prefix, void (*callback)(char *from, char *str))
 {
 	struct smsg_callback *cb;
 
@@ -108,7 +117,7 @@ smsg_register_callback(char *prefix, voi
 }
 
 void
-smsg_unregister_callback(char *prefix, void (*callback)(char *str))
+smsg_unregister_callback(char *prefix, void (*callback)(char *from, char *str))
 {
 	struct smsg_callback *cb, *tmp;
 
diff -puN drivers/s390/net/smsgiucv.h~s390-cmm-guest-sender-id drivers/s390/net/smsgiucv.h
--- 25/drivers/s390/net/smsgiucv.h~s390-cmm-guest-sender-id	2005-04-26 03:41:07.036488616 -0700
+++ 25-akpm/drivers/s390/net/smsgiucv.h	2005-04-26 03:41:07.041487856 -0700
@@ -5,6 +5,6 @@
  * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
  */
 
-int  smsg_register_callback(char *, void (*)(char *));
-void smsg_unregister_callback(char *, void (*)(char *));
+int  smsg_register_callback(char *, void (*)(char *, char *));
+void smsg_unregister_callback(char *, void (*)(char *, char *));
 
_