accel: Introduce the current_accel() wrapper

The accel/ code only accesses the MachineState::accel field.
As we simply want to access the accelerator, not the machine,
add a current_accel() wrapper.
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NAlistair Francis <alistair.francis@wdc.com>
Signed-off-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Message-Id: <20200121110349.25842-9-philmd@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

accel/accel.c

@@ -63,6 +63,11 @@ int accel_init_machine(AccelState *accel, MachineState *ms)
     return ret;
 }
 
+AccelState *current_accel(void)
+{
+    return current_machine->accelerator;
+}
+
 void accel_setup_post(MachineState *ms)
 {
     AccelState *accel = ms->accelerator;

include/sysemu/accel.h

@@ -70,4 +70,6 @@ int accel_init_machine(AccelState *accel, MachineState *ms);
 /* Called just before os_setup_post (ie just before drop OS privs) */
 void accel_setup_post(MachineState *ms);
 
+AccelState *current_accel(void);
+
 #endif