hw/mips: malta: Don't boot from flash with KVM T&E

In KVM trap & emulate (T&E) mode the flash reset region at 0xbfc00000
isn't executable, which is why the minimal kernel bootloader is loaded
and executed from the last 1MB of DRAM instead.

Therefore if no kernel is provided on the command line and KVM is
enabled, exit with an error since booting from flash will fail.
Reported-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/mips/mips_malta.c

@@ -1052,6 +1052,12 @@ void mips_malta_init(MachineState *machine)
                              bootloader_run_addr, kernel_entry);
         }
     } else {
+        /* The flash region isn't executable from a KVM T&E guest */
+        if (kvm_enabled()) {
+            error_report("KVM enabled but no -kernel argument was specified. "
+                         "Booting from flash is not supported with KVM T&E.");
+            exit(1);
+        }
         /* Load firmware from flash. */
         if (!dinfo) {
             /* Load a BIOS image. */