qdev/machine: Introduce hotplug_allowed hook

Introduce this new per-machine hook to give any machine class a chance
to do a sanity check on the to-be-hotplugged device as a sanity test.
This will be used for x86 to try to detect some illegal configuration
of devices, e.g., possible conflictions between vfio-pci and x86
vIOMMU.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20190916080718.3299-3-peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 2289536e48..be18a5c032 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -166,6 +166,13 @@ typedef struct {
  *    The function pointer to hook different machine specific functions for
  *    parsing "smp-opts" from QemuOpts to MachineState::CpuTopology and more
  *    machine specific topology fields, such as smp_dies for PCMachine.
+ * @hotplug_allowed:
+ *    If the hook is provided, then it'll be called for each device
+ *    hotplug to check whether the device hotplug is allowed.  Return
+ *    true to grant allowance or false to reject the hotplug.  When
+ *    false is returned, an error must be set to show the reason of
+ *    the rejection.  If the hook is not provided, all hotplug will be
+ *    allowed.
  */
 struct MachineClass {
     /*< private >*/
@@ -224,6 +231,8 @@ struct MachineClass {
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);
+    bool (*hotplug_allowed)(MachineState *state, DeviceState *dev,
+                            Error **errp);
     CpuInstanceProperties (*cpu_index_to_instance_props)(MachineState *machine,
                                                          unsigned cpu_index);
     const CPUArchIdList *(*possible_cpu_arch_ids)(MachineState *machine);