HMP: support specifying dump format for dump-guest-memory

Dumping guest memory is available to specify the dump format now. This patch
adds options '-z|-l|-s' to HMP command dump-guest-memory to specify dumping in
kdump-compression format, with zlib/lzo/snappy compression. And without these
options ELF format will be used.

The discussion about this feature is here:

http://lists.nongnu.org/archive/html/qemu-devel/2014-03/msg04235.html

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> (on s390x/kvm)
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

hmp-commands.hx

@@ -1000,10 +1000,13 @@ ETEXI
 
     {
         .name       = "dump-guest-memory",
-        .args_type  = "paging:-p,filename:F,begin:i?,length:i?",
-        .params     = "[-p] filename [begin length]",
+        .args_type  = "paging:-p,zlib:-z,lzo:-l,snappy:-s,filename:F,begin:i?,length:i?",
+        .params     = "[-p] [-z|-l|-s] filename [begin length]",
         .help       = "dump guest memory into file 'filename'.\n\t\t\t"
                       "-p: do paging to get guest's memory mapping.\n\t\t\t"
+                      "-z: dump in kdump-compressed format, with zlib compression.\n\t\t\t"
+                      "-l: dump in kdump-compressed format, with lzo compression.\n\t\t\t"
+                      "-s: dump in kdump-compressed format, with snappy compression.\n\t\t\t"
                       "begin: the starting physical address.\n\t\t\t"
                       "length: the memory size, in bytes.",
         .mhandler.cmd = hmp_dump_guest_memory,
@@ -1012,10 +1015,14 @@ ETEXI
 
 STEXI
 @item dump-guest-memory [-p] @var{filename} @var{begin} @var{length}
+@item dump-guest-memory [-z|-l|-s] @var{filename}
 @findex dump-guest-memory
 Dump guest memory to @var{protocol}. The file can be processed with crash or
-gdb.
+gdb. Without -z|-l|-s, the dump format is ELF.
         -p: do paging to get guest's memory mapping.
+        -z: dump in kdump-compressed format, with zlib compression.
+        -l: dump in kdump-compressed format, with lzo compression.
+        -s: dump in kdump-compressed format, with snappy compression.
   filename: dump file name.
      begin: the starting physical address. It's optional, and should be
             specified together with length.

hmp.c

@@ -1308,16 +1308,35 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict)
 {
     Error *errp = NULL;
     int paging = qdict_get_try_bool(qdict, "paging", 0);
+    int zlib = qdict_get_try_bool(qdict, "zlib", 0);
+    int lzo = qdict_get_try_bool(qdict, "lzo", 0);
+    int snappy = qdict_get_try_bool(qdict, "snappy", 0);
     const char *file = qdict_get_str(qdict, "filename");
     bool has_begin = qdict_haskey(qdict, "begin");
     bool has_length = qdict_haskey(qdict, "length");
-    /* kdump-compressed format is not supported for HMP */
-    bool has_format = false;
     int64_t begin = 0;
     int64_t length = 0;
     enum DumpGuestMemoryFormat dump_format = DUMP_GUEST_MEMORY_FORMAT_ELF;
     char *prot;
 
+    if (zlib + lzo + snappy > 1) {
+        error_setg(&errp, "only one of '-z|-l|-s' can be set");
+        hmp_handle_error(mon, &errp);
+        return;
+    }
+
+    if (zlib) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB;
+    }
+
+    if (lzo) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO;
+    }
+
+    if (snappy) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY;
+    }
+
     if (has_begin) {
         begin = qdict_get_int(qdict, "begin");
     }
@@ -1328,7 +1347,7 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict)
     prot = g_strconcat("file:", file, NULL);
 
     qmp_dump_guest_memory(paging, prot, has_begin, begin, has_length, length,
-                          has_format, dump_format, &errp);
+                          true, dump_format, &errp);
     hmp_handle_error(mon, &errp);
     g_free(prot);
 }