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b075aada8c
The test image file needs to be created before creating the filesystem on it. Signed-off-by: Rob Bradford <robert.bradford@intel.com>
78 lines
2.6 KiB
Markdown
78 lines
2.6 KiB
Markdown
# Cloud Hypervisor VFIO-user HOWTO
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VFIO-user is an *experimental* protocol for allowing devices to be implemented in another process and communicate over a socket; ie.e VFIO-user is to VFIO as virtio is to vhost-user.
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The protocol is documented here: https://github.com/nutanix/libvfio-user/blob/master/docs/vfio-user.rst
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The Cloud Hypervisor support for such devices is *experimental*. Not all Cloud Hypervisor functionality is supported in particular: virtio-mem and iommu are not supported.
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## Usage
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The `--user-device socket=<path>` parameter is used to create a vfio-user device when creating the VM specifying the socket to connect to. The device can also be hotplugged with `ch-remote add-user-device socket=<path>`.
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## Example (GPIO device)
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There is a simple GPIO device included in the libvfio-user repository: https://github.com/nutanix/libvfio-user#gpio
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Run the example from the libvfio-user repository:
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```sh
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rm /tmp/vfio-user.sock
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./build/dbg/samples/gpio-pci-idio-16 -v /tmp/vfio-user.sock &
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```
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Start Cloud Hypervisor:
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```sh
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target/debug/cloud-hypervisor \
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--memory size=1G,shared=on \
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--disk path=~/images/focal-server-cloudimg-amd64.raw \
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--kernel ~/src/linux/vmlinux \
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--cmdline "root=/dev/vda1 console=hvc0" \
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--user-device socket=/tmp/vfio-user.sock
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```
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Inside the VM you can test the device with:
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```sh
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cat /sys/class/gpio/gpiochip480/base > /sys/class/gpio/export
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for ((i=0;i<12;i++)); do cat /sys/class/gpio/OUT0/value; done
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```
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## Example (NVMe device)
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Use SPDK: https://github.com/spdk/spdk
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Compile with `./configure --with-vfio-user`
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Create an NVMe controller listening on a vfio-user socket with a simple block device:
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```sh
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sudo scripts/setup.sh
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rm ~/images/test-disk.raw
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truncate ~/images/test-disk.raw -s 128M
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mkfs.ext4 ~/images/test-disk.raw
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sudo killall ./build/bin/nvmf_tgt
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sudo ./build/bin/nvmf_tgt -i 0 -e 0xFFFF -m 0x1 &
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sleep 2
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sudo ./scripts/rpc.py nvmf_create_transport -t VFIOUSER
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sudo rm -rf /tmp/nvme-vfio-user
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sudo mkdir -p /tmp/nvme-vfio-user
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sudo ./scripts/rpc.py bdev_aio_create ~/images/test-disk.raw test 512
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sudo ./scripts/rpc.py nvmf_create_subsystem nqn.2019-07.io.spdk:cnode -a -s test
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sudo ./scripts/rpc.py nvmf_subsystem_add_ns nqn.2019-07.io.spdk:cnode test
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sudo ./scripts/rpc.py nvmf_subsystem_add_listener nqn.2019-07.io.spdk:cnode -t VFIOUSER -a /tmp/nvme-vfio-user -s 0
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sudo chown $USER.$USER -R /tmp/nvme-vfio-user
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```
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Start Cloud Hypervisor:
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```sh
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target/debug/cloud-hypervisor \
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--memory size=1G,shared=on \
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--disk path=~/images/focal-server-cloudimg-amd64.raw \
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--kernel ~/src/linux/vmlinux \
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--cmdline "root=/dev/vda1 console=hvc0" \
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--user-device socket=/tmp/nvme-vfio-user/cntrl
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```
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