[libvirt] [PATCH 2/4] qemu: add support for dump-guest-core option

[Martin Kletzander]

The "dump-guest-core' option is new option for the machine type
(-machine pc,dump-guest-core) that controls whether the guest memory
will be marked as dumpable.

While testing this, I've found out that the value for the '-M' options
is not parsed correctly when additional parameters are used. However,
when '-machine' is used for the same options, it gets parsed as
expected. That's why this patch also modifies the parsing and creating
of the command line, so both '-M' and '-machine' are recognized. In
QEMU's help there is only mention of the 'machine parameter now with
no sign of the older '-M'.
---
 src/qemu/qemu_capabilities.c |    4 ++
 src/qemu/qemu_capabilities.h |    1 +
 src/qemu/qemu_command.c      |   89 +++++++++++++++++++++++++++++++++++++----
 3 files changed, 85 insertions(+), 9 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index b8160b6..37d96b3 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -175,6 +175,7 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST,
               "disable-s3",
               "disable-s4",

+              "dump-guest-core", /* 101 */
     );

 struct qemu_feature_flags {
@@ -1175,6 +1176,9 @@ qemuCapsComputeCmdFlags(const char *help,
     if (strstr(help, "-no-shutdown") && (version < 14000 || version > 15000))
         qemuCapsSet(flags, QEMU_CAPS_NO_SHUTDOWN);

+    if (strstr(help, "dump-guest-core=on|off"))
+        qemuCapsSet(flags, QEMU_CAPS_DUMP_GUEST_CORE);
+
     /*
      * Handling of -incoming arg with varying features
      *  -incoming tcp    (kvm >= 79, qemu >= 0.10.0)
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index e49424a..f35b1b5 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -140,6 +140,7 @@ enum qemuCapsFlags {
     QEMU_CAPS_VIRTIO_SCSI_PCI    = 102, /* -device virtio-scsi-pci */
     QEMU_CAPS_DISABLE_S3         = 103, /* S3 BIOS Advertisement on/off */
     QEMU_CAPS_DISABLE_S4         = 104, /* S4 BIOS Advertisement on/off */
+    QEMU_CAPS_DUMP_GUEST_CORE    = 105, /* dump-guest-core parameter */

     QEMU_CAPS_LAST,                   /* this must always be the last item */
 };
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 34ee00e..0af5233 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -4190,6 +4190,53 @@ no_memory:
     goto cleanup;
 }

+static int
+qemuBuildMachineArgStr(virCommandPtr cmd,
+                       const virDomainDefPtr def,
+                       virBitmapPtr qemuCaps)
+{
+    /* This should *never* be NULL, since we always provide
+     * a machine in the capabilities data for QEMU. So this
+     * check is just here as a safety in case the unexpected
+     * happens */
+    if (def->os.machine) {
+        if (!def->mem.dump_core) {
+            /* if no parameter to the machine type is needed, we still use
+             * '-M' to keep the most of the compatibility with older versions.
+             */
+            virCommandAddArgList(cmd, "-M", def->os.machine, NULL);
+        } else {
+            char *machine = NULL;
+
+            if (!qemuCapsGet(qemuCaps, QEMU_CAPS_DUMP_GUEST_CORE)) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               "%s", _("dump-guest-core is not available "
+                                       " with this QEMU binary"));
+                return -1;
+            }
+
+            virAsprintf(&machine,
+                        "%s,%s=%s",
+                        def->os.machine,
+                        "dump-guest-core",
+                        virDomainMemDumpTypeToString(def->mem.dump_core));
+
+            if (machine == NULL) {
+                virReportOOMError();
+                return -1;
+            }
+
+            /* However, in case there is a parameter to be added, we need to
+             * use the "-machine" parameter because qemu is not parsing the
+             * "-M" correctly */
+            virCommandAddArgList(cmd, "-machine", machine, NULL);
+            VIR_FREE(machine);
+        }
+    }
+
+    return 0;
+}
+
 static char *
 qemuBuildSmpArgStr(const virDomainDefPtr def,
                    virBitmapPtr qemuCaps)
@@ -4403,12 +4450,8 @@ qemuBuildCommandLine(virConnectPtr conn,
     }
     virCommandAddArg(cmd, "-S"); /* freeze CPU */

-    /* This should *never* be NULL, since we always provide
-     * a machine in the capabilities data for QEMU. So this
-     * check is just here as a safety in case the unexpected
-     * happens */
-    if (def->os.machine)
-        virCommandAddArgList(cmd, "-M", def->os.machine, NULL);
+    if (qemuBuildMachineArgStr(cmd, def, qemuCaps) < 0)
+        goto error;

     if (qemuBuildCpuArgStr(driver, def, emulator, qemuCaps,
                            &ut, &cpu, &hasHwVirt, !!migrateFrom) < 0)
@@ -8091,10 +8134,38 @@ virDomainDefPtr qemuParseCommandLine(virCapsPtr caps,
             }
             if (STREQ(def->name, ""))
                 VIR_FREE(def->name);
-        } else if (STREQ(arg, "-M")) {
+        } else if (STREQ(arg, "-M") ||
+                   STREQ(arg, "-machine")) {
+            char *params;
             WANT_VALUE();
-            if (!(def->os.machine = strdup(val)))
-                goto no_memory;
+            params = strchr(val, ',');
+            if (params == NULL) {
+                if (!(def->os.machine = strdup(val)))
+                    goto no_memory;
+            } else {
+                if (!(def->os.machine = strndup(val, params - val)))
+                    goto no_memory;
+
+                while(params++) {
+                    /* prepared for more "-machine" parameters */
+                    const char *tmp = params;
+                    params = strchr(params, ',');
+
+                    if (STRPREFIX(tmp, "dump-guest-core=")) {
+                        tmp += strlen("dump-guest-core=");
+                        if (params) {
+                            tmp = strndup(tmp, params - tmp);
+                            if (tmp == NULL)
+                                goto no_memory;
+                        }
+                        def->mem.dump_core = virDomainMemDumpTypeFromString(tmp);
+                        if (def->mem.dump_core == -1)
+                            def->mem.dump_core = VIR_DOMAIN_MEM_DUMP_DEFAULT;
+                        if (params)
+                            VIR_FREE(tmp);
+                    }
+                }
+            }
         } else if (STREQ(arg, "-serial")) {
             WANT_VALUE();
             if (STRNEQ(val, "none")) {
-- 
1.7.8.6