63 lines
2.3 KiB
Go
63 lines
2.3 KiB
Go
package vm
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import (
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"fmt"
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"qvm/internal/config"
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"qvm/internal/virtiofsd"
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"strconv"
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)
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// HotplugSlots is the number of PCIe root ports reserved for hot-plugging
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// workspace mounts into a running VM. Each hot-mounted virtiofs device needs
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// its own root port since pcie.0 does not support hotplug.
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const HotplugSlots = 16
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// HotplugBusPrefix is the bus ID prefix for hotplug-capable PCIe root ports.
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// Slots are named hotplug0, hotplug1, ..., hotplugN.
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const HotplugBusPrefix = "hotplug"
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// buildQEMUCommand builds the QEMU command line for virtiofsd-based mounts.
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// Uses vhost-user-fs-pci devices for boot-time mounts and provisions empty
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// PCIe root ports for hot-plugging additional mounts at runtime.
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func buildQEMUCommand(cfg *config.Config, sshPort int, mounts []virtiofsd.Mount) []string {
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memSize := cfg.VM.Memory
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// vhost-user-fs requires shared memory backend with share=on
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// We must specify memory size only via the memory backend and attach it to NUMA
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// The -m flag must match the memory backend size for QEMU to be happy
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args := []string{
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"-machine", "q35,memory-backend=mem",
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"-accel", "kvm",
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"-cpu", "host",
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"-object", fmt.Sprintf("memory-backend-memfd,id=mem,size=%s,share=on", memSize),
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"-smp", strconv.Itoa(cfg.VM.CPUs),
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"-display", "none",
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"-daemonize",
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"-pidfile", config.PIDFile,
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"-drive", fmt.Sprintf("file=%s,if=virtio,format=qcow2", config.Overlay),
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"-netdev", fmt.Sprintf("user,id=n0,hostfwd=tcp::%d-:22", sshPort),
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"-device", "virtio-net-pci,netdev=n0",
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"-serial", fmt.Sprintf("file:%s", config.SerialLog),
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"-qmp", fmt.Sprintf("unix:%s,server,nowait", config.QMPSocket),
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}
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// Add vhost-user-fs devices for each boot-time mount
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for _, mount := range mounts {
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args = append(args,
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"-chardev", fmt.Sprintf("socket,id=%s,path=%s", mount.Tag, mount.SocketPath),
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"-device", fmt.Sprintf("vhost-user-fs-pci,queue-size=1024,chardev=%s,tag=%s", mount.Tag, mount.Tag),
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)
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}
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// Provision empty PCIe root ports for hot-plugging workspace mounts.
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// The q35 root bus (pcie.0) does not support hotplug, so we need
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// dedicated root ports that accept device_add at runtime.
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for i := 0; i < HotplugSlots; i++ {
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busID := fmt.Sprintf("%s%d", HotplugBusPrefix, i)
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args = append(args,
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"-device", fmt.Sprintf("pcie-root-port,id=%s,slot=%d", busID, i+1),
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)
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}
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return args
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}
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