Reference

vmm(4)

virtual machine monitor

NAME

vmm – virtual machine monitor

SYNOPSIS

vmm0 at mainbus0

#include <machine/vmmvar.h>

DESCRIPTION

The vmm driver implements a virtual machine monitor (VMM) suitable for executing virtual machines (VMs). A VMM runs on the host operating system and provides facilities to execute one or more VMs, each of which is provided with a suitable complement of virtual hardware.

These VMs run independently of the host, but may interact with it as any other machine would (e.g. via network communications or other means).

VMs are allocated hardware resources by the VMM during creation, including:

  • Virtual CPUs

  • Virtual network interfaces

  • Virtual disk images

  • Virtual serial ports

Although VMs execute independently of each other and the host, they do consume host resources and, as such, the number of VMs (and their configurations) should be taken into consideration when planning host capacity.

The vmm driver requires suitable host CPU capabilities in order to provide VM services. The vmm driver requires at least one CPU with hardware-assisted virtualization capabilities and nested or extended paging capabilities to be present on the host. For more information, consult the CPU vendor's documentation.

The following ioctl(2) commands are provided through two interfaces:

/dev/vmm

Control device for creating VMs.

VM file descriptor

Per-VM handle returned by VMM_IOC_CREATE. The lifetime of a VM is tied to this descriptor. Closing the last reference to it tears down the VM.

The following ioctl call applies to the /dev/vmm control device:

VMM_IOC_CREATE struct vm_create_params *

Create a VM via /dev/vmm, initializing vmm if not yet started. Returns a VM file descriptor in vcp_fd. (Does not start the VCPU.)

The following ioctl calls apply to the VM file descriptor returned by VMM_IOC_CREATE.

VMM_IOC_RUN struct vm_run_params *

Run a VCPU and return on VM-exit, when the VCPU stopped, or on error.

VMM_IOC_RESETCPU struct vm_resetcpu_params *

Reset a VCPU to power-on-init state using the provided register state.

VMM_IOC_INTR struct vm_intr_params *

Signal a pending interrupt for a VCPU.

VMM_IOC_READREGS struct vm_rwregs_params *

Read registers of a VCPU.

VMM_IOC_WRITEREGS struct vm_rwregs_params *

Write register values of a VCPU.

VMM_IOC_READVMPARAMS struct vm_rwvmparams_params *

Read paravirtualized hardware parameters (such as pvclock(4) version) for a VM.

VMM_IOC_WRITEVMPARAMS struct vm_rwvmparams_params *

Write paravirtualized hardware parameters (such as pvclock(4) guest physical address) for a VM.

VMM_IOC_SHAREMEM struct vm_sharemem_params *

Create shared mappings for the VM memory ranges into the calling process.

SEE ALSO

cpu(4), intro(4), virtio(4), vmctl(8), vmd(8)

HISTORY

The vmm driver appeared in OpenBSD 5.9.

AUTHORS

Mike Larkin ⟨[email protected]⟩