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4d43d3f3c8
Current support for bus master (clearing OK bit) together with the need to support guests which do not enable PCI bus mastering, leads to extra state in VIRTIO_PCI_FLAG_BUS_MASTER_BUG bit, which isn't robust in case of cross-version migration for the case when guests use the device before setting DRIVER_OK. Rip out VIRTIO_PCI_FLAG_BUS_MASTER_BUG and implement a simpler work-around: treat clearing of PCI_COMMAND as a virtio reset. Old guests never touch this bit so they will work. As reset clears device status, DRIVER and MASTER bits are now in sync, so we can fix up cross-version migration simply by synchronising them, without need to detect a buggy guest explicitly. Drop tracking VIRTIO_PCI_FLAG_BUS_MASTER_BUG completely. As reset makes the device quiescent, in the future we'll be able to drop checking OK bit in a bunch of places. Cc: Jason Wang <jasowang@redhat.com> Cc: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> |
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| .. | ||
| dataplane | ||
| Makefile.objs | ||
| vhost-backend.c | ||
| vhost-user.c | ||
| vhost.c | ||
| virtio-balloon.c | ||
| virtio-bus.c | ||
| virtio-mmio.c | ||
| virtio-pci.c | ||
| virtio-pci.h | ||
| virtio-rng.c | ||
| virtio.c | ||