hw/i386/pc: Ensure vmport prerequisites are fulfilled

Since commit 4ccd5fe22feb95137d325f422016a6473541fe9f ('pc: add option
to disable PS/2 mouse/keyboard'), the vmport will not be created unless
the i8042 PS/2 controller is enabled. To avoid confusion, let's fail if
vmport was explicitly requested, but the i8042 controller is disabled.
This also changes the behavior of vmport=auto to take i8042 controller
availability into account.

Signed-off-by: Kamil Szczęk <kamil@szczek.dev>
Reviewed-by: Bernhard Beschow <shentey@gmail.com>
Message-ID: <0MS3y5E-hHqODIhiuFxmCnIrXd612JIGq31UuMsz4KGCKZ_wWuF-PHGKTRSGS0nWaPEddOdF4YOczHdgorulECPo792OhWov7O9BBF6UMX4=@szczek.dev>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

hw/i386/pc.c

@@ -1075,7 +1075,7 @@ static const MemoryRegionOps ioportF0_io_ops = {
 };
 
 static void pc_superio_init(ISABus *isa_bus, bool create_fdctrl,
-                            bool create_i8042, bool no_vmport)
+                            bool create_i8042, bool no_vmport, Error **errp)
 {
     int i;
     DriveInfo *fd[MAX_FD];
@@ -1100,6 +1100,10 @@ static void pc_superio_init(ISABus *isa_bus, bool create_fdctrl,
     }
 
     if (!create_i8042) {
+        if (!no_vmport) {
+            error_setg(errp,
+                       "vmport requires the i8042 controller to be enabled");
+        }
         return;
     }
 
@@ -1219,12 +1223,13 @@ void pc_basic_device_init(struct PCMachineState *pcms,
 
     assert(pcms->vmport >= 0 && pcms->vmport < ON_OFF_AUTO__MAX);
     if (pcms->vmport == ON_OFF_AUTO_AUTO) {
-        pcms->vmport = xen_enabled() ? ON_OFF_AUTO_OFF : ON_OFF_AUTO_ON;
+        pcms->vmport = (xen_enabled() || !pcms->i8042_enabled)
+            ? ON_OFF_AUTO_OFF : ON_OFF_AUTO_ON;
     }
 
     /* Super I/O */
     pc_superio_init(isa_bus, create_fdctrl, pcms->i8042_enabled,
-                    pcms->vmport != ON_OFF_AUTO_ON);
+                    pcms->vmport != ON_OFF_AUTO_ON, &error_fatal);
 }
 
 void pc_nic_init(PCMachineClass *pcmc, ISABus *isa_bus, PCIBus *pci_bus)

qemu-options.hx

@@ -68,8 +68,8 @@ SRST
 
     ``vmport=on|off|auto``
         Enables emulation of VMWare IO port, for vmmouse etc. auto says
-        to select the value based on accel. For accel=xen the default is
-        off otherwise the default is on.
+        to select the value based on accel and i8042. For accel=xen or
+        i8042=off the default is off otherwise the default is on.
 
     ``dump-guest-core=on|off``
         Include guest memory in a core dump. The default is on.