qemu: recognize -machine accel=kvm when parsing native

In Fedora 19, 'qemu-kvm' is a simple wrapper that calls
'qemu-system-x86_64 -machine accel=kvm'.  Attempting
to use 'virsh qemu-attach $pid' to a machine started as:

qemu-kvm -cdrom /var/lib/libvirt/images/foo.img \
 -monitor unix:/tmp/demo,server,nowait -name foo \
 --uuid cece4f9f-dff0-575d-0e8e-01fe380f12ea

was failing with:
error: XML error: No PCI buses available

because we did not see 'kvm' in the executable name read from
/proc/$pid/cmdline, and tried to assign os.machine as
"accel=kvm" instead of "pc"; this in turn led to refusal to
recognize the pci bus.

Noticed while investigating https://bugzilla.redhat.com/995312
although there are still other issues to fix before that bug
will be completely solved.

I've concluded that the existing parser code for native-to-xml
is a horrendous hodge-podge of ad-hoc approaches; I basically
rewrote the -machine section to be a bit saner.

* src/qemu/qemu_command.c (qemuParseCommandLine): Don't assume
-machine argument is always appropriate for os.machine; set
virtType if accel is present.
Signed-off-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_command.c

@@ -11352,35 +11352,42 @@ qemuParseCommandLine(virCapsPtr qemuCaps,
                 VIR_FREE(def->name);
         } else if (STREQ(arg, "-M") ||
                    STREQ(arg, "-machine")) {
-            char *params;
-            WANT_VALUE();
-            params = strchr(val, ',');
-            if (params == NULL) {
-                if (VIR_STRDUP(def->os.machine, val) < 0)
-                    goto error;
-            } else {
-                if (VIR_STRNDUP(def->os.machine, val, params - val) < 0)
-                    goto error;
+            char **list;
+            char *param;
+            size_t j = 0;
 
-                while (params++) {
-                    /* prepared for more "-machine" parameters */
-                    char *tmp = params;
-                    params = strchr(params, ',');
+            /* -machine [type=]name[,prop[=value][,...]]
+             * Set os.machine only if first parameter lacks '=' or
+             * contains explicit type='...' */
+            WANT_VALUE();
+            list = virStringSplit(val, ",", 0);
+            param = list[0];
 
-                    if (STRPREFIX(tmp, "dump-guest-core=")) {
-                        tmp += strlen("dump-guest-core=");
-                        if (params && VIR_STRNDUP(tmp, tmp, params - tmp) < 0)
+            if (STRPREFIX(param, "type="))
+                param += strlen("type=");
+            if (!strchr(param, '=')) {
+                if (VIR_STRDUP(def->os.machine, param) < 0) {
+                    virStringFreeList(list);
                     goto error;
-                        def->mem.dump_core = virDomainMemDumpTypeFromString(tmp);
+                }
+                j++;
+            }
+
+            /* handle all remaining "-machine" parameters */
+            while ((param = list[j++])) {
+                if (STRPREFIX(param, "dump-guest-core=")) {
+                    param += strlen("dump-guest-core=");
+                    def->mem.dump_core = virDomainMemDumpTypeFromString(param);
                     if (def->mem.dump_core <= 0)
                         def->mem.dump_core = VIR_DOMAIN_MEM_DUMP_DEFAULT;
-                        if (params)
-                            VIR_FREE(tmp);
-                    } else if (STRPREFIX(tmp, "mem-merge=off")) {
+                } else if (STRPREFIX(param, "mem-merge=off")) {
                     def->mem.nosharepages = true;
+                } else if (STRPREFIX(param, "accel=kvm")) {
+                    def->virtType = VIR_DOMAIN_VIRT_KVM;
+                    def->features |= (1 << VIR_DOMAIN_FEATURE_PAE);
                 }
             }
-            }
+            virStringFreeList(list);
         } else if (STREQ(arg, "-serial")) {
             WANT_VALUE();
             if (STRNEQ(val, "none")) {