machine: Provide a function to check the dynamic sysbus allowlist

Provide a new function dynamic_sysbus_dev_allowed() which checks the
per-machine list of permitted dynamic sysbus devices and returns a
boolean result indicating whether the device is allowed.  We can use
this in the implementation of validate_sysbus_device(), but we will
also need it so that machine hotplug callbacks can validate devices
rather than assuming that any sysbus device might be hotpluggable
into the platform bus.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-id: 20210325153310.9131-3-peter.maydell@linaro.org

1 files changed, 24 insertions, 0 deletions

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 6fc5cefcec..ad6c8fd537 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -52,6 +52,30 @@ void machine_set_cpu_numa_node(MachineState *machine,
  */
 void machine_class_allow_dynamic_sysbus_dev(MachineClass *mc, const char *type);
 
+/**
+ * device_is_dynamic_sysbus: test whether device is a dynamic sysbus device
+ * @mc: Machine class
+ * @dev: device to check
+ *
+ * Returns: true if @dev is a sysbus device on the machine's list
+ * of dynamically pluggable sysbus devices; otherwise false.
+ *
+ * This function checks whether @dev is a valid dynamic sysbus device,
+ * by first confirming that it is a sysbus device and then checking it
+ * against the list of permitted dynamic sysbus devices which has been
+ * set up by the machine using machine_class_allow_dynamic_sysbus_dev().
+ *
+ * It is valid to call this with something that is not a subclass of
+ * TYPE_SYS_BUS_DEVICE; the function will return false in this case.
+ * This allows hotplug callback functions to be written as:
+ *     if (device_is_dynamic_sysbus(mc, dev)) {
+ *         handle dynamic sysbus case;
+ *     } else if (some other kind of hotplug) {
+ *         handle that;
+ *     }
+ */
+bool device_is_dynamic_sysbus(MachineClass *mc, DeviceState *dev);
+
 /*
  * Checks that backend isn't used, preps it for exclusive usage and
  * returns migratable MemoryRegion provided by backend.