qemu/include/hw/virtio/virtio-access.h
Greg Kurz e5157e313c virtio: optimize virtio_access_is_big_endian() for little-endian targets
When adding cross-endian support, we introduced the TARGET_IS_BIENDIAN macro
and the virtio_access_is_big_endian() helper to have a branchless fast path
in the virtio memory accessors for targets that don't switch endian.

This was considered as a strong requirement at the time.

Now we have added a runtime check for virtio 1.0, which ruins the benefit
of the virtio_access_is_big_endian() helper for always little-endian targets.

With this patch, always little-endian targets stop checking for virtio 1.0,
since the result is little-endian in all cases.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
2016-02-16 12:05:18 +02:00

175 lines
4.4 KiB
C

/*
* 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)
if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
/* Devices conforming to VIRTIO 1.0 or later are always LE. */
return false;
}
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 */