mirror of
https://github.com/arehnman/yttrium-virtio-gpu.git
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Yuri Benditovich
fccd454db4
Described how the failover feature works including latest changes. Updated also list of supported adapters. Signed-off-by: Yuri Benditovich <[email protected]>
98 lines
4.1 KiB
Markdown
98 lines
4.1 KiB
Markdown
# NETKVM support for 'failover' feature
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If the virtio-net-pci device is configured with 'failover=on'
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in the command line the virtio-net is not expected to be used
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as a standalone device but in combination with Virtual function
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(VF) of a SRIOV-capable host adapter. In this case the virtio-net
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and the VF must have identical MAC addresses.
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Unlike implementation of virtio-net failover feature in Linux
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failover virtio-net device in Windows starts function only after
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the VIOPROT protocol driver is installed:
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1. System start without VIOPROT installed:
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NETKVM driver **does not indicate link-up** until it recognizes
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presence of respective VF with the same MAC address (for that
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the VIOPROT is required)
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2. Upon VIOPROT installation the NETKVM adapter **indicates link-up**
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and starts working using VF data channel to its respective
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SRIOV physical function (PF)
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3. When the migration process is started the QEMU hides the VF
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device on the PCI bus, VF adapter on the source VM disappears
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and the NETKVM continues transferring data via TAP adapter
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on the host it is configured to use (typically this TAP
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adapter is attached to the same bridge as the PF.
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4. Until the migration is completed the virtio-net/NETKVM is
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the **fallback network adapter on the guest OS** (similar to Linux).
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Note that on this stage of the migration the VF is not used
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by the VM anymore. But because the VF is present and has the same
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MAC address as the virtio-net device it is possible that the PF
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will drop the traffic that comes from the virtio-net via its TAP
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as the network patckets usually have the same source MAC address
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as the VF. So, it is highly recommended to change the MAC address
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of the VF as soon as it is hidden on the VM PCI bus.
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5. When the migration is done QEMU attaches a new VF to the PCI bus
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of the VM on the destination system. NETKVM recognizes it and switches
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to the datapath of the new VF.
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# Notify object of VIOPROT protocol supported by NETKVM
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The notify object runs on protocol installation (it checks all the
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existing adapters) and on installation of new adapter (it checks the
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new adapter):
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If the adapter's PnP ID matches the list of supported ones, the notify
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object unbinds it from all the protocols and binds only to VIOPROT.
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It there is NETKVM adapter with the MAC address identical to one of
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checked netwrok adapter, these 2 adapters with the same MAC address
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will be 'teamed' (subject to compatibility check) and the NETKVM uses
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the teamed adapter for RX and TX.
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## Protocol installation
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(by admin, from the directory where vioprot.inf is located)
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See: InstallProtocol.cmd
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netcfg -v -l vioprot.inf -c p -i VIOPROT
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## Protocol uninstallation (example of the batch):
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See: UninstallProtocol.cmd
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netcfg -v -u VIOPROT
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timeout /t 3
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for %%f in (c:\windows\inf\oem*.inf) do call :checkinf %%f
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echo Done
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timeout /t 3
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goto :eof
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:checkinf
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type %1 | findstr /i vioprot.cat
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if not errorlevel 1 goto :removeinf
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echo %1 is not VIOPROT inf file
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goto :eof
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:removeinf
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echo This is VIOPROT inf file
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pnputil /d "%~nx1"
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timeout /t 2
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goto :eof
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## Supported adapters
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Built-in list at the moment of writing:
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* "ven_8086&dev_1515" - Intel X540 Virtual Function
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* "ven_8086&dev_10ca" - Intel 82576 Virtual Function
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* "ven_8086&dev_15a8" - Intel Ethernet Connection X552
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* "ven_8086&dev_154c" - Intel 700 Series VF
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* "ven_8086&dev_10ed" - Intel 82599 VF
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* "ven_15b3&dev_101a" - Mellanox MT28800 Family
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* "ven_14e4&dev_16dc" - Broadcom NetXtreme-E Virtual Function
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* "ven_14e4&dev_16af" - Broadcom NetXtreme II BCM57810 Virtual Function
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* "...bdrv\\l2ndv&pci_16af14e4" - Broadcom NetXtreme II BCM57810 Virtual Function (QLogic miniport driver)
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## Change the list of supported adapter without rebuilding the binary
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Registry key: **HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\VioProt**
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*Name* | *Type* | *Value* | *Note*
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---------------|----------|---------|--------
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**NoDefaults** | DWORD | 1 | Disables built-in list
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**Supported** | MULTI_SZ | List | Substrings in format "ven_XXXX&dev_XXXX", for example: "ven_8086&dev_1520XXXX"
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**Note: Never include PnP ID of NETKVM adapter!**
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