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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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ea5a050341
Change the block size to the standard 512 byte sector size to that disk images can be used (since their partition tables will be specified in terms of 512 byte sectors.) Also remove the hugepages=on option from the command line as it is not necessary. 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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mkfs.ext4 ~/images/test-disk.raw
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truncate ~/images/test-disk.raw -s 128M
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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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