Allowing for the future possibility of implementing AML-based
(i.e., firmware-triggered) access to the QEMU fw_cfg device,
acquire the global ACPI lock when accessing the device on behalf
of the guest-side sysfs driver, to prevent any potential race
conditions.
Suggested-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NGabriel Somlo <somlo@cmu.edu>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>