Replace -no-virtio-balloon by -balloon

We want to do (at least) two things to the virtio-balloon device:
suppress it, and control its PCI address.  Option -no-virtio-balloon
lets us do only the former.  To get the latter, replace
-no-virtio-balloon with

    -balloon none   disable balloon device
    -balloon virtio[,addr=str]
                    enable virtio balloon device (default)

Syntax suggested by Anthony Liguori.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/pc.c

@@ -1408,8 +1408,9 @@ static void pc_init1(ram_addr_t ram_size,
     }
 
     /* Add virtio balloon device */
-    if (pci_enabled && !no_virtio_balloon) {
-        pci_create_simple(pci_bus, -1, "virtio-balloon-pci");
+    if (pci_enabled && virtio_balloon) {
+        pci_dev = pci_create("virtio-balloon-pci", virtio_balloon_devaddr);
+        qdev_init(&pci_dev->qdev);
     }
 
     /* Add virtio console devices */

qemu-options.hx

@@ -684,12 +684,17 @@ Disable HPET support.
 ETEXI
 
 #ifdef TARGET_I386
-DEF("no-virtio-balloon", 0, QEMU_OPTION_no_virtio_balloon,
-    "-no-virtio-balloon disable virtio balloon device\n")
+DEF("balloon", HAS_ARG, QEMU_OPTION_balloon,
+    "-balloon none   disable balloon device\n"
+    "-balloon virtio[,addr=str]\n"
+    "                enable virtio balloon device (default)\n")
 #endif
 STEXI
-@item -no-virtio-balloon
-Disable virtio-balloon device.
+@item -balloon none
+Disable balloon device.
+@item -balloon virtio[,addr=@var{addr}]
+Enable virtio balloon device (default), optionally with PCI address
+@var{addr}.
 ETEXI
 
 #ifdef TARGET_I386

sysemu.h

@@ -116,7 +116,8 @@ extern int win2k_install_hack;
 extern int rtc_td_hack;
 extern int alt_grab;
 extern int usb_enabled;
-extern int no_virtio_balloon;
+extern int virtio_balloon;
+extern const char *virtio_balloon_devaddr;
 extern int smp_cpus;
 extern int cursor_hide;
 extern int graphic_rotate;

vl.c

@@ -242,7 +242,8 @@ int smp_cpus = 1;
 const char *vnc_display;
 int acpi_enabled = 1;
 int no_hpet = 0;
-int no_virtio_balloon = 0;
+int virtio_balloon = 1;
+const char *virtio_balloon_devaddr;
 int fd_bootchk = 1;
 int no_reboot = 0;
 int no_shutdown = 0;
@@ -4762,6 +4763,29 @@ static void select_vgahw (const char *p)
     }
 }
 
+#ifdef TARGET_I386
+static int balloon_parse(const char *arg)
+{
+    char buf[128];
+    const char *p;
+
+    if (!strcmp(arg, "none")) {
+        virtio_balloon = 0;
+    } else if (!strncmp(arg, "virtio", 6)) {
+        virtio_balloon = 1;
+        if (arg[6] == ',')  {
+            p = arg + 7;
+            if (get_param_value(buf, sizeof(buf), "addr", p)) {
+                virtio_balloon_devaddr = strdup(buf);
+            }
+        }
+    } else {
+        return -1;
+    }
+    return 0;
+}
+#endif
+
 #ifdef _WIN32
 static BOOL WINAPI qemu_ctrl_handler(DWORD type)
 {
@@ -5578,8 +5602,11 @@ int main(int argc, char **argv, char **envp)
             case QEMU_OPTION_no_hpet:
                 no_hpet = 1;
                 break;
-            case QEMU_OPTION_no_virtio_balloon:
-                no_virtio_balloon = 1;
+            case QEMU_OPTION_balloon:
+                if (balloon_parse(optarg) < 0) {
+                    fprintf(stderr, "Unknown -balloon argument %s\n", optarg);
+                    exit(1);
+                }
                 break;
 #endif
             case QEMU_OPTION_no_reboot: