On Tue, Jun 26, 2018 at 10:49:30PM -0500, Venu Busireddy wrote: > The patch set "Enable virtio_net to act as a standby for a passthru > device" [1] deals with live migration of guests that use passthrough > devices. However, that scheme uses the MAC address for pairing > the virtio device and the passthrough device. The thread "netvsc: > refactor notifier/event handling code to use the failover framework" > [2] discusses an alternate mechanism, such as using an UUID, for pairing > the devices. Based on that discussion, proposals "Add "Group Identifier" > to virtio PCI capabilities." [3] and "RFC: Use of bridge devices to > store pairing information..." [4] were made. > > The current patch set includes all the feedback received for proposals [3] > and [4]. For the sake of completeness, patch for the virtio specification > is also included here. Following is the updated proposal. > > 1. Extend the virtio specification to include a new virtio PCI capability > "VIRTIO_PCI_CAP_GROUP_ID_CFG".
There's still discussion around whether it should be a virtio pci capability, a virtio net config field or a new kind of capability. > 2. Enhance the QEMU CLI to include a "uuid" option to the virtio device. > The "uuid" is a string in UUID format. > > 3. Enhance the QEMU CLI to include a "uuid" option to the bridge device. > The "uuid" is a string in UUID format. Currently, PCIe bridge for > the Q35 model is supported. > > 4. The operator creates a unique identifier string using 'uuidgen'. > > 5. When the virtio device is created, the operator uses the "uuid" option > (for example, '-device virtio-net-pci,uuid="string"') and specifies > the UUID created in step 4. > > QEMU stores the UUID in the virtio device's configuration space > in the capability "VIRTIO_PCI_CAP_GROUP_ID_CFG". > > 6. When assigning a PCI device to the guest in passthrough mode, the > operator first creates a bridge using the "uuid" option (for example, > '-device pcie-downstream,uuid="string"') to specify the UUID created > in step 4, and then attaches the passthrough device to the bridge. > > QEMU stores the UUID in the configuration space of the bridge as > Vendor-Specific capability (0x09). The "Vendor" here is not to be > confused with a specific organization. Instead, the vendor of the > bridge is QEMU. To avoid mixing up with other bridges, the bridge > will be created with vendor ID 0x1b36 (PCI_VENDOR_ID_REDHAT) and > device ID 0x000e (PCI_DEVICE_ID_REDHAT_PCIE_BRIDGE) if the "uuid" > option is specified. Otherwise, current defaults are used. > > 7. Patch 4 in patch series "Enable virtio_net to act as a standby for > a passthru device" [1] needs to be modified to use the UUID values > present in the bridge's configuration space and the virtio device's > configuration space instead of the MAC address for pairing the devices. > > Thanks! > > Venu The part where the visibility of a vfio device is controlled by the virtio driver acknowledging the backup feature is missing here. > [1] https://lists.oasis-open.org/archives/virtio-dev/201805/msg00156.html > [2] https://www.spinics.net/lists/netdev/msg499011.html > [3] https://lists.oasis-open.org/archives/virtio-dev/201805/msg00118.html > [4] https://lists.oasis-open.org/archives/virtio-dev/201805/msg00204.html > > Changes in v2: > - As Michael Tsirkin suggested, changed the virtio specification > to restrict the group identifier to be a 16-byte field, presented > entirely in the virtio device's configuration space. > - As Michael Tsirkin suggested, instead of tweaking the ioh3420 > device with Red Hat vendor ID, create a new PCIe bridge device > named "pcie-downstream" with Red Hat Vendor ID, and include the > group identifier in this device. > - Added a new patch to enhance the "pci-bridge" device to support > the group identifier (for the i440FX model). > > Venu Busireddy (4): > Add a true or false option to the DEFINE_PROP_UUID macro. > Add "Group Identifier" support to virtio devices. > Add "Group Identifier" support to Red Hat PCI bridge. > Add "Group Identifier" support to Red Hat PCI Express bridge. > > default-configs/arm-softmmu.mak | 1 + > default-configs/i386-softmmu.mak | 1 + > default-configs/x86_64-softmmu.mak | 1 + > hw/acpi/vmgenid.c | 2 +- > hw/pci-bridge/Makefile.objs | 1 + > hw/pci-bridge/pci_bridge_dev.c | 8 + > hw/pci-bridge/pcie_downstream.c | 215 ++++++++++++++++++++ > hw/pci-bridge/pcie_downstream.h | 10 + > hw/pci/pci_bridge.c | 26 +++ > hw/virtio/virtio-pci.c | 15 ++ > hw/virtio/virtio-pci.h | 3 +- > include/hw/pci/pci.h | 3 + > include/hw/pci/pcie.h | 1 + > include/hw/qdev-properties.h | 4 +- > include/standard-headers/linux/virtio_pci.h | 8 + > 15 files changed, 295 insertions(+), 4 deletions(-) > create mode 100644 hw/pci-bridge/pcie_downstream.c > create mode 100644 hw/pci-bridge/pcie_downstream.h --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org
