From: Rusty Russell <address@hidden>
virtio data structures are defined as "target endian", which assumes
that's a fixed value. In fact, that actually means it's platform-specific.
The OASIS virtio 1.0 spec will fix this, by making all little endian.
We need to support both implementations and we want to share as much code
as possible.
A good way to do it is to introduce a per-device boolean property to tell
memory accessors whether they should swap bytes or not. This flag should
be set at device reset time, because:
- endianness won't change while the device is in use, and if we reboot
into a different endianness, a new device reset will occur
- as suggested by Alexander Graf, we can keep all the logic to set the
property in a single place and share all the virtio memory accessors
between the two implementations
For legacy devices, we rely on a per-platform hook to set the flag. The
virtio 1.0 implementation will just have to add some more logic in
virtio_reset() instead of calling the hook:
if (vdev->legacy) {
vdev->needs_byteswap = virtio_legacy_get_byteswap();
} else {
#ifdef HOST_WORDS_BIGENDIAN
vdev->needs_byteswap = true;
#else
vdev->needs_byteswap = false;
#endif
}
The needs_byteswap flag is preserved accross migrations.
Signed-off-by: Rusty Russell <address@hidden>
[ fixed checkpatch.pl error with the virtio_byteswap initialisation,
ldq_phys() API change,
relicensed virtio-access.h to GPLv2+ on Rusty's request,
introduce a per-device needs_byteswap flag,
add VirtIODevice * arg to virtio helpers,
rename virtio_get_byteswap to virtio_legacy_get_byteswap,
Greg Kurz <address@hidden> ]
Signed-off-by: Greg Kurz <address@hidden>
---
hw/virtio/virtio.c | 5 +
include/hw/virtio/virtio-access.h | 139 +++++++++++++++++++++++++++++++++++++
include/hw/virtio/virtio.h | 3 +
stubs/Makefile.objs | 1
stubs/virtio_get_byteswap.c | 6 ++
5 files changed, 154 insertions(+)
create mode 100644 include/hw/virtio/virtio-access.h
create mode 100644 stubs/virtio_get_byteswap.c
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index aeabf3a..24b565f 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -19,6 +19,7 @@
#include "hw/virtio/virtio.h"
#include "qemu/atomic.h"
#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-access.h"
/*
* The alignment to use between consumer and producer parts of vring.
@@ -546,6 +547,8 @@ void virtio_reset(void *opaque)
virtio_set_status(vdev, 0);
+ vdev->needs_byteswap = virtio_legacy_get_byteswap();
+
if (k->reset) {
k->reset(vdev);
}
@@ -845,6 +848,7 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
qemu_put_8s(f, &vdev->status);
qemu_put_8s(f, &vdev->isr);
+ qemu_put_8s(f, (uint8_t *) &vdev->needs_byteswap);
qemu_put_be16s(f, &vdev->queue_sel);
qemu_put_be32s(f, &vdev->guest_features);
qemu_put_be32(f, vdev->config_len);
@@ -905,6 +909,7 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
qemu_get_8s(f, &vdev->status);
qemu_get_8s(f, &vdev->isr);
+ qemu_get_8s(f, (uint8_t *) &vdev->needs_byteswap);
qemu_get_be16s(f, &vdev->queue_sel);
qemu_get_be32s(f, &features);
diff --git a/include/hw/virtio/virtio-access.h b/include/hw/virtio/virtio-access.h
new file mode 100644
index 0000000..70dd1e2
--- /dev/null
+++ b/include/hw/virtio/virtio-access.h
@@ -0,0 +1,139 @@
+/*
+ * Virtio Accessor Support: In case your target can change endian.
+ *
+ * Copyright IBM, Corp. 2013
+ *
+ * Authors:
+ * Rusty Russell <address@hidden>
+ *
+ * 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"
+
+static inline uint16_t virtio_lduw_phys(AddressSpace *as, hwaddr pa,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap16(lduw_phys(as, pa));
+ }
+ return lduw_phys(as, pa);
+}
+
+static inline uint32_t virtio_ldl_phys(AddressSpace *as, hwaddr pa,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap32(ldl_phys(as, pa));
+ }
+ return ldl_phys(as, pa);
+}
+
+static inline uint64_t virtio_ldq_phys(AddressSpace *as, hwaddr pa,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap64(ldq_phys(as, pa));
+ }
+ return ldq_phys(as, pa);
+}
+
+static inline void virtio_stw_phys(AddressSpace *as, hwaddr pa, uint16_t value,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ stw_phys(as, pa, bswap16(value));
+ } else {
+ stw_phys(as, pa, value);
+ }
+}
+
+static inline void virtio_stl_phys(AddressSpace *as, hwaddr pa, uint32_t value,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ stl_phys(as, pa, bswap32(value));
+ } else {
+ stl_phys(as, pa, value);
+ }
+}
+
+static inline void virtio_stw_p(void *ptr, uint16_t v,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ stw_p(ptr, bswap16(v));
+ } else {
+ stw_p(ptr, v);
+ }
+}
+
+static inline void virtio_stl_p(void *ptr, uint32_t v,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ stl_p(ptr, bswap32(v));
+ } else {
+ stl_p(ptr, v);
+ }
+}
+
+static inline void virtio_stq_p(void *ptr, uint64_t v,
+ struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ stq_p(ptr, bswap64(v));
+ } else {
+ stq_p(ptr, v);
+ }
+}
+
+static inline int virtio_lduw_p(const void *ptr, struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap16(lduw_p(ptr));
+ } else {
+ return lduw_p(ptr);
+ }
+}
+
+static inline int virtio_ldl_p(const void *ptr, struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap32(ldl_p(ptr));
+ } else {
+ return ldl_p(ptr);
+ }
+}
+
+static inline uint64_t virtio_ldq_p(const void *ptr, struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap64(ldq_p(ptr));
+ } else {
+ return ldq_p(ptr);
+ }
+}
+
+static inline uint32_t virtio_tswap32(uint32_t s, struct VirtIODevice *vdev)
+{
+ if (vdev->needs_byteswap) {
+ return bswap32(tswap32(s));
+ } else {
+ return tswap32(s);
+ }
+}
+
+static inline void virtio_tswap32s(uint32_t *s, struct VirtIODevice *vdev)
+{
+ tswap32s(s);
+ if (vdev->needs_byteswap) {
+ *s = bswap32(*s);
+ }