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This patch adds support for VDPA network simulation devices. The device is developed based on virtio-net and tap backend, and supports hardware live migration function. For more details, please refer to "docs/system/devices/vdpa-net.rst" Signed-off-by: Hao Chen <chenh@yusur.tech> Message-Id: <20240221073802.2888022-1-chenh@yusur.tech> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
121 lines
6.1 KiB
ReStructuredText
121 lines
6.1 KiB
ReStructuredText
vdpa net
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============
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This document explains the setup and usage of the vdpa network device.
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The vdpa network device is a paravirtualized vdpa emulate device.
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Description
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-----------
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VDPA net devices support dirty page bitmap mark and vring state saving and recovery.
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Users can use this VDPA device for live migration simulation testing in a nested virtualization environment.
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Registers layout
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----------------
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The vdpa device add live migrate registers layout as follow::
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Offset Register Name Bitwidth Associated vq
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0x0 LM_LOGGING_CTRL 4bits
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0x10 LM_BASE_ADDR_LOW 32bits
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0x14 LM_BASE_ADDR_HIGH 32bits
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0x18 LM_END_ADDR_LOW 32bits
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0x1c LM_END_ADDR_HIGH 32bits
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0x20 LM_RING_STATE_OFFSET 32bits vq0
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0x24 LM_RING_STATE_OFFSET 32bits vq1
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0x28 LM_RING_STATE_OFFSET 32bits vq2
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......
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0x20+1023*4 LM_RING_STATE_OFFSET 32bits vq1023
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These registers are extended at the end of the notify bar space.
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Architecture diagram
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--------------------
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::
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|------------------------------------------------------------------------|
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| guest-L1-user-space |
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| |----------------------------------------|
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| | [virtio-net driver] |
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| | ^ guest-L2-src(iommu=on) |
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| |--------------|-------------------------|
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| | | qemu-L2-src(viommu) |
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| [dpdk-vdpa]<->[vhost socket]<-+->[vhost-user backend(iommu=on)] |
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--------------------------------------------------------------------------
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--------------------------------------------------------------------------
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| ^ guest-L1-kernel-space |
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| | |
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| [VFIO] |
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| ^ |
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| | guest-L1-src(iommu=on) |
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--------|-----------------------------------------------------------------
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--------|-----------------------------------------------------------------
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| [vdpa net device(iommu=on)] [manager nic device] |
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| | | |
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| [tap device] qemu-L1-src(viommu) | |
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------------------------------------------------+-------------------------
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--------------------- |
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| kernel net bridge |<-----
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| virbr0 |<----------------------------------
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--------------------- |
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-------------------------------------------------------------------------- |
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| guest-L1-user-space | |
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| |----------------------------------------| |
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| | [virtio-net driver] | |
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| | ^ guest-L2-dst(iommu=on) | |
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| |--------------|-------------------------| |
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| | | qemu-L2-dst(viommu) | |
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| [dpdk-vdpa]<->[vhost socket]<-+->[vhost-user backend(iommu=on)] | |
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-------------------------------------------------------------------------- |
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-------------------------------------------------------------------------- |
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| ^ guest-L1-kernel-space | |
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| | | |
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| [VFIO] | |
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| ^ | |
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| | guest-L1-dst(iommu=on) | |
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--------|----------------------------------------------------------------- |
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--------|----------------------------------------------------------------- |
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| [vdpa net device(iommu=on)] [manager nic device]----------------+----
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| [tap device] qemu-L1-dst(viommu) |
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--------------------------------------------------------------------------
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Device properties
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-----------------
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The Virtio vdpa device can be configured with the following properties:
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* ``vdpa=on`` open vdpa device emulated.
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Usages
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--------
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This patch add virtio sriov support and vdpa live migrate support.
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You can open vdpa by set xml file as follow::
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<qemu:commandline xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
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<qemu:arg value='-device'/>
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<qemu:arg value='intel-iommu,intremap=on,device-iotlb=on,aw-bits=48'/>
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<qemu:arg value='-netdev'/>
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<qemu:arg value='tap,id=hostnet1,script=no,downscript=no,vhost=off'/>
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<qemu:arg value='-device'/>
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<qemu:arg value='virtio-net-pci,netdev=hostnet1,id=net1,mac=56:4a:b7:4f:4d:a9,bus=pci.6,addr=0x0,iommu_platform=on,ats=on,vdpa=on'/>
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</qemu:commandline>
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Limitations
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-----------
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1. Dependent on tap device with param ``vhost=off``.
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2. Nested virtualization environment only supports ``q35`` machines.
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3. Current only support split vring live migrate.
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