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Subject: Re: [virtio-dev] Re: [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices...
On Tue, Jun 26, 2018 at 9:06 PM, Michael S. Tsirkin <mst@redhat.com> wrote: > 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. While it is still being discussed, I tend to put that effort into a seperate set of patches, and this patch series comes first just for enabling guest to use the UUID feature (I've some code pending). Does this division makes sense? I realize that the vfio's visibility work would need to take a while. -Siwei > > >> [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-unsubscribe@lists.oasis-open.org > For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org >
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