virtio: memory accessors for endian-ambivalent targets

This is the virtio-access.h header file taken from Rusty's "endian-ambivalent
targets using legacy virtio" patch. It introduces helpers that should be used
when accessing vring data or by drivers for data that contains headers.
The virtio config space is also target endian, but the current code already
handles that with the virtio_is_big_endian() helper. There is no obvious
benefit at using the virtio accessors in this case.

Now we have two distinct paths: a fast inline one for fixed endian targets,
and a slow out-of-line one for targets that define the new TARGET_IS_BIENDIAN
macro.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
[ relicensed virtio-access.h to GPLv2+ on Rusty's request,
  pass &address_space_memory to physical memory accessors,
  per-device endianness,
  virtio tswap16 and tswap64 helpers,
  faspath for fixed endian targets,
  Greg Kurz <gkurz@linux.vnet.ibm.com> ]
Cc: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

include/hw/virtio/virtio-access.h

@@ -0,0 +1,170 @@
+/*
+ * Virtio Accessor Support: In case your target can change endian.
+ *
+ * Copyright IBM, Corp. 2013
+ *
+ * Authors:
+ *  Rusty Russell   <rusty@au.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+#ifndef _QEMU_VIRTIO_ACCESS_H
+#define _QEMU_VIRTIO_ACCESS_H
+#include "hw/virtio/virtio.h"
+#include "exec/address-spaces.h"
+
+static inline bool virtio_access_is_big_endian(VirtIODevice *vdev)
+{
+#if defined(TARGET_IS_BIENDIAN)
+    return virtio_is_big_endian(vdev);
+#elif defined(TARGET_WORDS_BIGENDIAN)
+    return true;
+#else
+    return false;
+#endif
+}
+
+static inline uint16_t virtio_lduw_phys(VirtIODevice *vdev, hwaddr pa)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        return lduw_be_phys(&address_space_memory, pa);
+    }
+    return lduw_le_phys(&address_space_memory, pa);
+}
+
+static inline uint32_t virtio_ldl_phys(VirtIODevice *vdev, hwaddr pa)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        return ldl_be_phys(&address_space_memory, pa);
+    }
+    return ldl_le_phys(&address_space_memory, pa);
+}
+
+static inline uint64_t virtio_ldq_phys(VirtIODevice *vdev, hwaddr pa)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        return ldq_be_phys(&address_space_memory, pa);
+    }
+    return ldq_le_phys(&address_space_memory, pa);
+}
+
+static inline void virtio_stw_phys(VirtIODevice *vdev, hwaddr pa,
+                                   uint16_t value)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        stw_be_phys(&address_space_memory, pa, value);
+    } else {
+        stw_le_phys(&address_space_memory, pa, value);
+    }
+}
+
+static inline void virtio_stl_phys(VirtIODevice *vdev, hwaddr pa,
+                                   uint32_t value)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        stl_be_phys(&address_space_memory, pa, value);
+    } else {
+        stl_le_phys(&address_space_memory, pa, value);
+    }
+}
+
+static inline void virtio_stw_p(VirtIODevice *vdev, void *ptr, uint16_t v)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        stw_be_p(ptr, v);
+    } else {
+        stw_le_p(ptr, v);
+    }
+}
+
+static inline void virtio_stl_p(VirtIODevice *vdev, void *ptr, uint32_t v)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        stl_be_p(ptr, v);
+    } else {
+        stl_le_p(ptr, v);
+    }
+}
+
+static inline void virtio_stq_p(VirtIODevice *vdev, void *ptr, uint64_t v)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        stq_be_p(ptr, v);
+    } else {
+        stq_le_p(ptr, v);
+    }
+}
+
+static inline int virtio_lduw_p(VirtIODevice *vdev, const void *ptr)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        return lduw_be_p(ptr);
+    } else {
+        return lduw_le_p(ptr);
+    }
+}
+
+static inline int virtio_ldl_p(VirtIODevice *vdev, const void *ptr)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        return ldl_be_p(ptr);
+    } else {
+        return ldl_le_p(ptr);
+    }
+}
+
+static inline uint64_t virtio_ldq_p(VirtIODevice *vdev, const void *ptr)
+{
+    if (virtio_access_is_big_endian(vdev)) {
+        return ldq_be_p(ptr);
+    } else {
+        return ldq_le_p(ptr);
+    }
+}
+
+static inline uint16_t virtio_tswap16(VirtIODevice *vdev, uint16_t s)
+{
+#ifdef HOST_WORDS_BIGENDIAN
+    return virtio_access_is_big_endian(vdev) ? s : bswap16(s);
+#else
+    return virtio_access_is_big_endian(vdev) ? bswap16(s) : s;
+#endif
+}
+
+static inline void virtio_tswap16s(VirtIODevice *vdev, uint16_t *s)
+{
+    *s = virtio_tswap16(vdev, *s);
+}
+
+static inline uint32_t virtio_tswap32(VirtIODevice *vdev, uint32_t s)
+{
+#ifdef HOST_WORDS_BIGENDIAN
+    return virtio_access_is_big_endian(vdev) ? s : bswap32(s);
+#else
+    return virtio_access_is_big_endian(vdev) ? bswap32(s) : s;
+#endif
+}
+
+static inline void virtio_tswap32s(VirtIODevice *vdev, uint32_t *s)
+{
+    *s = virtio_tswap32(vdev, *s);
+}
+
+static inline uint64_t virtio_tswap64(VirtIODevice *vdev, uint64_t s)
+{
+#ifdef HOST_WORDS_BIGENDIAN
+    return virtio_access_is_big_endian(vdev) ? s : bswap64(s);
+#else
+    return virtio_access_is_big_endian(vdev) ? bswap64(s) : s;
+#endif
+}
+
+static inline void virtio_tswap64s(VirtIODevice *vdev, uint64_t *s)
+{
+    *s = virtio_tswap64(vdev, *s);
+}
+#endif /* _QEMU_VIRTIO_ACCESS_H */