s390x: Info skeys sub-command

Provide an  info skeys hmp sub-command to allow the end user to dump a storage
key for a given address. This is useful for guest operating system developers.

Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

hmp-commands.hx

@@ -1806,6 +1806,8 @@ show roms
 show the TPM device
 @item info memory-devices
 show the memory devices
+@item info skeys
+Display the value of a storage key (s390 only)
 @end table
 ETEXI
 

hw/s390x/s390-skeys.c

@@ -66,6 +66,29 @@ static void write_keys(QEMUFile *f, uint8_t *keys, uint64_t startgfn,
     }
 }
 
+void hmp_info_skeys(Monitor *mon, const QDict *qdict)
+{
+    S390SKeysState *ss = s390_get_skeys_device();
+    S390SKeysClass *skeyclass = S390_SKEYS_GET_CLASS(ss);
+    uint64_t addr = qdict_get_int(qdict, "addr");
+    uint8_t key;
+    int r;
+
+    /* Quick check to see if guest is using storage keys*/
+    if (!skeyclass->skeys_enabled(ss)) {
+        monitor_printf(mon, "Error: This guest is not using storage keys\n");
+        return;
+    }
+
+    r = skeyclass->get_skeys(ss, addr / TARGET_PAGE_SIZE, 1, &key);
+    if (r < 0) {
+        monitor_printf(mon, "Error: %s\n", strerror(-r));
+        return;
+    }
+
+    monitor_printf(mon, "  key: 0x%X\n", key);
+}
+
 void hmp_dump_skeys(Monitor *mon, const QDict *qdict)
 {
     const char *filename = qdict_get_str(qdict, "filename");

include/hw/s390x/storage-keys.h

@@ -54,4 +54,6 @@ void s390_skeys_init(void);
 S390SKeysState *s390_get_skeys_device(void);
 
 void hmp_dump_skeys(Monitor *mon, const QDict *qdict);
+void hmp_info_skeys(Monitor *mon, const QDict *qdict);
+
 #endif /* __S390_STORAGE_KEYS_H */

monitor.c

@@ -2881,6 +2881,15 @@ static mon_cmd_t info_cmds[] = {
         .help       = "Show rocker OF-DPA groups",
         .mhandler.cmd = hmp_rocker_of_dpa_groups,
     },
+#if defined(TARGET_S390X)
+    {
+        .name       = "skeys",
+        .args_type  = "addr:l",
+        .params     = "address",
+        .help       = "Display the value of a storage key",
+        .mhandler.cmd = hmp_info_skeys,
+    },
+#endif
     {
         .name       = NULL,
     },