virtio: move bi-endian target support to a single location

Paolo's recent cpu.h cleanups broke legacy virtio for ppc64 LE guests (and
arm BE guests as well, even if I have not verified that). Especially, commit
"33c11879 qemu-common: push cpu.h inclusion out of qemu-common.h" has
the side-effect of silently hiding the TARGET_IS_BIENDIAN macro from the
virtio memory accessors, and thus fully disabling support of endian changing
targets.

To be sure this cannot happen again, let's gather all the bi-endian bits
where they belong in include/hw/virtio/virtio-access.h.

The changes in hw/virtio/vhost.c are safe because vhost_needs_vring_endian()
is not called on a hot path and non bi-endian targets will return false
anyway.

While here, also rename TARGET_IS_BIENDIAN to be more precise: it is only for
legacy virtio and bi-endian guests.
Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NCédric Le Goater <clg@kaod.org>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/virtio/vhost.c

@@ -767,15 +767,11 @@ static inline bool vhost_needs_vring_endian(VirtIODevice *vdev)
     if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
         return false;
     }
-#ifdef TARGET_IS_BIENDIAN
 #ifdef HOST_WORDS_BIGENDIAN
     return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE;
 #else
     return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG;
 #endif
-#else
-    return false;
-#endif
 }
 
 static int vhost_virtqueue_set_vring_endian_legacy(struct vhost_dev *dev,

include/hw/virtio/virtio-access.h

@@ -17,9 +17,13 @@
 #include "hw/virtio/virtio.h"
 #include "exec/address-spaces.h"
 
+#if defined(TARGET_PPC64) || defined(TARGET_ARM)
+#define LEGACY_VIRTIO_IS_BIENDIAN 1
+#endif
+
 static inline bool virtio_access_is_big_endian(VirtIODevice *vdev)
 {
-#if defined(TARGET_IS_BIENDIAN)
+#if defined(LEGACY_VIRTIO_IS_BIENDIAN)
     return virtio_is_big_endian(vdev);
 #elif defined(TARGET_WORDS_BIGENDIAN)
     if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {

target-arm/cpu.h

@@ -29,8 +29,6 @@
 #  define TARGET_LONG_BITS 32
 #endif
 
-#define TARGET_IS_BIENDIAN 1
-
 #define CPUArchState struct CPUARMState
 
 #include "qemu-common.h"

target-ppc/cpu.h

@@ -28,8 +28,6 @@
 #define TARGET_LONG_BITS 64
 #define TARGET_PAGE_BITS 12
 
-#define TARGET_IS_BIENDIAN 1
-
 /* Note that the official physical address space bits is 62-M where M
    is implementation dependent.  I've not looked up M for the set of
    cpus we emulate at the system level.  */