[PATCH v2 qemu 3/3] dump: Add qmp argument "reassembled"

[Stephen Brennan <stephen.s.brennan@oracle.com>]

This can be used from QMP command line as "-R" to mirror the
corresponding flag for makedumpfile. This enables the kdump_reassembled
flag introduced in the previous patch.

Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
---
 dump/dump-hmp-cmds.c |  8 +++++++-
 dump/dump.c          | 12 +++++++++++-
 hmp-commands.hx      |  7 +++++--
 qapi/dump.json       | 14 +++++++++++++-
 4 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/dump/dump-hmp-cmds.c b/dump/dump-hmp-cmds.c
index b038785fee..1d882e4bd8 100644
--- a/dump/dump-hmp-cmds.c
+++ b/dump/dump-hmp-cmds.c
@@ -24,9 +24,11 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict)
     bool has_begin = qdict_haskey(qdict, "begin");
     bool has_length = qdict_haskey(qdict, "length");
     bool has_detach = qdict_haskey(qdict, "detach");
+    bool has_reassembled = qdict_haskey(qdict, "reassembled");
     int64_t begin = 0;
     int64_t length = 0;
     bool detach = false;
+    bool reassembled = false;
     enum DumpGuestMemoryFormat dump_format = DUMP_GUEST_MEMORY_FORMAT_ELF;
     char *prot;
 
@@ -61,11 +63,15 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict)
     if (has_detach) {
         detach = qdict_get_bool(qdict, "detach");
     }
+    if (has_reassembled) {
+        reassembled = qdict_get_bool(qdict, "reassembled");
+    }
 
     prot = g_strconcat("file:", file, NULL);
 
     qmp_dump_guest_memory(paging, prot, true, detach, has_begin, begin,
-                          has_length, length, true, dump_format, &err);
+                          has_length, length, true, has_reassembled,
+                          reassembled, dump_format, &err);
     hmp_handle_error(mon, err);
     g_free(prot);
 }
diff --git a/dump/dump.c b/dump/dump.c
index fb9040cfbc..42d4015fb3 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -2089,6 +2089,7 @@ void qmp_dump_guest_memory(bool paging, const char *file,
                            bool has_detach, bool detach,
                            bool has_begin, int64_t begin, bool has_length,
                            int64_t length, bool has_format,
+                           bool has_reassembled, bool reassembled,
                            DumpGuestMemoryFormat format, Error **errp)
 {
     ERRP_GUARD();
@@ -2119,6 +2120,12 @@ void qmp_dump_guest_memory(bool paging, const char *file,
                          "filter");
         return;
     }
+    if (has_reassembled && format != DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB
+                        && format != DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO
+                        && format != DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY) {
+        error_setg(errp, "'reassembled' only applies to kdump format");
+        return;
+    }
     if (has_begin && !has_length) {
         error_setg(errp, QERR_MISSING_PARAMETER, "length");
         return;
@@ -2130,6 +2137,9 @@ void qmp_dump_guest_memory(bool paging, const char *file,
     if (has_detach) {
         detach_p = detach;
     }
+    if (!has_reassembled) {
+        reassembled = false;
+    }
 
     /* check whether lzo/snappy is supported */
 #ifndef CONFIG_LZO
@@ -2192,7 +2202,7 @@ void qmp_dump_guest_memory(bool paging, const char *file,
     dump_state_prepare(s);
 
     dump_init(s, fd, has_format, format, paging, has_begin,
-              begin, length, false, errp);
+              begin, length, reassembled, errp);
     if (*errp) {
         qatomic_set(&s->status, DUMP_STATUS_FAILED);
         return;
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 2cbd0f77a0..c3062da470 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1085,14 +1085,15 @@ ERST
 
     {
         .name       = "dump-guest-memory",
-        .args_type  = "paging:-p,detach:-d,windmp:-w,zlib:-z,lzo:-l,snappy:-s,filename:F,begin:l?,length:l?",
-        .params     = "[-p] [-d] [-z|-l|-s|-w] filename [begin length]",
+        .args_type  = "paging:-p,detach:-d,windmp:-w,zlib:-z,lzo:-l,snappy:-s,reassembled:-R,filename:F,begin:l?,length:l?",
+        .params     = "[-p] [-d] [-z|-l|-s|-w] [-R] 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"
                       "-d: return immediately (do not wait for completion).\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"
+                      "-R: when using kdump (-z, -l, -s), try to avoid the flattened format.\n\t\t\t"
                       "-w: dump in Windows crashdump format (can be used instead of ELF-dump converting),\n\t\t\t"
                       "    for Windows x86 and x64 guests with vmcoreinfo driver only.\n\t\t\t"
                       "begin: the starting physical address.\n\t\t\t"
@@ -1115,6 +1116,8 @@ SRST
     dump in kdump-compressed format, with lzo compression.
   ``-s``
     dump in kdump-compressed format, with snappy compression.
+  ``-R``
+    when using kdump (-z, -l, -s), try to avoid the flattened format.
   ``-w``
     dump in Windows crashdump format (can be used instead of ELF-dump converting),
     for Windows x64 guests with vmcoreinfo driver only
diff --git a/qapi/dump.json b/qapi/dump.json
index 4ae1f722a9..9cc7c3ea93 100644
--- a/qapi/dump.json
+++ b/qapi/dump.json
@@ -69,6 +69,18 @@
 #     to dump all guest's memory, please specify the start @begin and
 #     @length
 #
+# @reassembled: if false (the default), the kdump output formats will use the
+#     "makedumpfile flattened" variant of the format, which is less broadly
+#     compatible with analysis tools. The flattened dump can be reassembled
+#     after the fact using the command "makedumpfile -R". If true, Qemu
+#     attempts to generate the standard kdump format. This requires a
+#     seekable file as output -- if the output file is not seekable, then
+#     the flattened format is still generated. The standard format is more
+#     broadly compatible with debugging tools, but generating it requires a
+#     seekable output file descriptor, and could use more system memory due
+#     to page cache utilization. This should be left unspecified for non-kdump
+#     output formats.
+#
 # @format: if specified, the format of guest memory dump.  But non-elf
 #     format is conflict with paging and filter, ie.  @paging, @begin
 #     and @length is not allowed to be specified with non-elf @format
@@ -89,7 +101,7 @@
 { 'command': 'dump-guest-memory',
   'data': { 'paging': 'bool', 'protocol': 'str', '*detach': 'bool',
             '*begin': 'int', '*length': 'int',
-            '*format': 'DumpGuestMemoryFormat'} }
+            '*reassembled': 'bool', '*format': 'DumpGuestMemoryFormat'} }
 
 ##
 # @DumpStatus:
-- 
2.39.3