Fix for crash after migration in virtio-rng on bi-endian targets
VirtIO devices now remember which endianness they're operating in in order to support targets which may have guests of either endianness, such as powerpc. This endianness state is transferred in a subsection of the virtio device's information. With virtio-rng this can lead to an abort after a loadvm hitting the assert() in virtio_is_big_endian(). This can be reproduced by doing a migrate and load from file on a bi-endian target with a virtio-rng device. The actual guest state isn't particularly important to triggering this. The cause is that virtio_rng_load_device() calls virtio_rng_process() which accesses the ring and thus needs the endianness. However, virtio_rng_process() is called via virtio_load() before it loads the subsections. Essentially the ->load callback in VirtioDeviceClass should only be used for actually reading the device state from the stream, not for post-load re-initialization. This patch fixes the bug by moving the virtio_rng_process() after the call to virtio_load(). Better yet would be to convert virtio to use vmsd and have the virtio_rng_process() as a post_load callback, but that's a bigger project for another day. This is bugfix, and should be considered for the 2.2 branch. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Message-id: 1417067290-20715-1-git-send-email-david@gibson.dropbear.id.au Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@ -113,20 +113,22 @@ static void virtio_rng_save(QEMUFile *f, void *opaque)
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static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id)
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static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id)
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{
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{
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VirtIORNG *vrng = opaque;
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int ret;
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if (version_id != 1) {
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if (version_id != 1) {
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return -EINVAL;
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return -EINVAL;
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}
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}
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return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
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ret = virtio_load(VIRTIO_DEVICE(vrng), f, version_id);
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}
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if (ret != 0) {
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return ret;
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}
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static int virtio_rng_load_device(VirtIODevice *vdev, QEMUFile *f,
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int version_id)
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{
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/* We may have an element ready but couldn't process it due to a quota
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/* We may have an element ready but couldn't process it due to a quota
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* limit. Make sure to try again after live migration when the quota may
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* limit. Make sure to try again after live migration when the quota may
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* have been reset.
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* have been reset.
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*/
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*/
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virtio_rng_process(VIRTIO_RNG(vdev));
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virtio_rng_process(vrng);
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return 0;
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return 0;
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}
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}
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@ -231,7 +233,6 @@ static void virtio_rng_class_init(ObjectClass *klass, void *data)
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vdc->realize = virtio_rng_device_realize;
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vdc->realize = virtio_rng_device_realize;
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vdc->unrealize = virtio_rng_device_unrealize;
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vdc->unrealize = virtio_rng_device_unrealize;
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vdc->get_features = get_features;
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vdc->get_features = get_features;
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vdc->load = virtio_rng_load_device;
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}
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}
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static void virtio_rng_initfn(Object *obj)
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static void virtio_rng_initfn(Object *obj)
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