Some CPU families can dynamically change their endianness. This means we
can have little endian ppc or big endian arm guests for example. This has
an impact on legacy virtio data structures since they are target endian.
We hence introduce a new property to track the endianness of each virtio
device. It is reasonnably assumed that endianness won't change while the
device is in use : we hence capture the device endianness when it gets
reset.
We migrate this property in a subsection, after the device descriptor. This
means the load code must not rely on it until it is restored. As a consequence,
the vring sanity checks had to be moved after the call to vmstate_load_state().
We enforce paranoia by poisoning the property at the begining of virtio_load().
Signed-off-by: Greg Kurz <address@hidden>
---
Changes since last version (virtio migration RFC):
- endianness cached at device reset time
- reworked migration support
hw/virtio/virtio-pci.c | 8 ++--
hw/virtio/virtio.c | 100 +++++++++++++++++++++++++++++++++++++++-----
include/hw/virtio/virtio.h | 12 ++++-
3 files changed, 102 insertions(+), 18 deletions(-)
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 390c8d2..2ffceb8 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -406,13 +406,13 @@ static uint64_t virtio_pci_config_read(void *opaque,
hwaddr addr,
break;
case 2:
val = virtio_config_readw(vdev, addr);
- if (virtio_is_big_endian()) {
+ if (virtio_is_big_endian(vdev)) {
val = bswap16(val);
}
break;
case 4:
val = virtio_config_readl(vdev, addr);
- if (virtio_is_big_endian()) {
+ if (virtio_is_big_endian(vdev)) {
val = bswap32(val);
}
break;
@@ -440,13 +440,13 @@ static void virtio_pci_config_write(void *opaque, hwaddr
addr,
virtio_config_writeb(vdev, addr, val);
break;
case 2:
- if (virtio_is_big_endian()) {
+ if (virtio_is_big_endian(vdev)) {
val = bswap16(val);
}
virtio_config_writew(vdev, addr, val);
break;
case 4:
- if (virtio_is_big_endian()) {
+ if (virtio_is_big_endian(vdev)) {
val = bswap32(val);
}
virtio_config_writel(vdev, addr, val);
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 16b73d9..6235df8 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -545,6 +545,24 @@ void virtio_set_status(VirtIODevice *vdev, uint8_t val)
vdev->status = val;
}
+static void virtio_set_endian_target_default(VirtIODevice *vdev)
+{
+#ifdef TARGET_WORDS_BIGENDIAN
+ vdev->device_endian = VIRTIO_DEVICE_ENDIAN_BIG;
+#else
+ vdev->device_endian = VIRTIO_DEVICE_ENDIAN_LITTLE;
+#endif
+}
+
+static void virtio_set_endian_cpu(VirtIODevice *vdev, CPUState *cpu)
+{
+ if (cpu_virtio_is_big_endian(cpu)) {
+ vdev->device_endian = VIRTIO_DEVICE_ENDIAN_BIG;
+ } else {
+ vdev->device_endian = VIRTIO_DEVICE_ENDIAN_LITTLE;
+ }
+}
+
void virtio_reset(void *opaque)
{
VirtIODevice *vdev = opaque;
@@ -552,6 +570,13 @@ void virtio_reset(void *opaque)
int i;
virtio_set_status(vdev, 0);
+ if (current_cpu) {
+ /* Guest initiated reset */
+ virtio_set_endian_cpu(vdev, current_cpu);
+ } else {
+ /* System reset */
+ virtio_set_endian_target_default(vdev);
+ }
if (k->reset) {
k->reset(vdev);
@@ -840,6 +865,28 @@ void virtio_notify_config(VirtIODevice *vdev)
virtio_notify_vector(vdev, vdev->config_vector);
}
+static bool virtio_device_endian_needed(void *opaque)
+{
+ VirtIODevice *vdev = opaque;
+
+ assert(vdev->device_endian != VIRTIO_DEVICE_ENDIAN_UNKNOWN);
+#ifdef TARGET_WORDS_BIGENDIAN
+ return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE;
+#else
+ return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG;
+#endif