s390x: fix build for --without-default-devices

s390-pci-vfio.c calls into the vfio code, so we need it to be
built conditionally on vfio (which implies CONFIG_LINUX).

Fixes: cd7498d0 ("s390x/pci: Add routine to get the vfio dma available count")
Reported-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Message-Id: <20201103123237.718242-1-cohuck@redhat.com>
Acked-by: Greg Kurz <groug@kaod.org>
Tested-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>

hw/s390x/meson.build

@@ -27,7 +27,7 @@ s390x_ss.add(when: 'CONFIG_KVM', if_true: files(
 ))
 s390x_ss.add(when: 'CONFIG_S390_CCW_VIRTIO', if_true: files('s390-virtio-ccw.c'))
 s390x_ss.add(when: 'CONFIG_TERMINAL3270', if_true: files('3270-ccw.c'))
-s390x_ss.add(when: 'CONFIG_LINUX', if_true: files('s390-pci-vfio.c'))
+s390x_ss.add(when: 'CONFIG_VFIO', if_true: files('s390-pci-vfio.c'))
 
 virtio_ss = ss.source_set()
 virtio_ss.add(files('virtio-ccw.c'))

include/hw/s390x/s390-pci-vfio.h

@@ -13,8 +13,9 @@
 #define HW_S390_PCI_VFIO_H
 
 #include "hw/s390x/s390-pci-bus.h"
+#include CONFIG_DEVICES
 
-#ifdef CONFIG_LINUX
+#ifdef CONFIG_VFIO
 bool s390_pci_update_dma_avail(int fd, unsigned int *avail);
 S390PCIDMACount *s390_pci_start_dma_count(S390pciState *s,
                                           S390PCIBusDevice *pbdev);