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Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing vir
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices... |
Date: |
Wed, 27 Jun 2018 07:06:42 +0300 |
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
- [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Venu Busireddy, 2018/06/26
- [Qemu-devel] [PATCH v2 4/4] Add "Group Identifier" support to Red Hat PCI Express bridge., Venu Busireddy, 2018/06/26
- [Qemu-devel] [PATCH v2 virtio 1/1] Add "Group Identifier" to virtio PCI capabilities., Venu Busireddy, 2018/06/26
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices...,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Roman Kagan, 2018/06/27
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Venu Busireddy, 2018/06/27
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Michael S. Tsirkin, 2018/06/27
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Venu Busireddy, 2018/06/27
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Michael S. Tsirkin, 2018/06/27
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Venu Busireddy, 2018/06/27
- Re: [Qemu-devel] [PATCH v2 0/4] Use of unique identifier for pairing virtio and passthrough devices..., Michael S. Tsirkin, 2018/06/27