VMM(4)

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 for managing vmm guests:

VMM_IOC_CREATE struct vm_create_params *
    Create a VM, initializing vmm if not yet started. (Does not start the VCPU.)

VMM_IOC_RUN struct vm_run_params *
    Run a VCPU for a defined VM. Return on VM-exit, when the VCPU stopped, or an error occurred.

VMM_IOC_INFO struct vm_info_params *
    Get information about the VMs currently hosted by vmm.

VMM_IOC_TERM struct vm_terminate_params *
    Terminate a given VM.

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_MPROTECT_EPT struct vm_mprotect_ept_params *
    Set access protections on guest page table entries (only supported on hosts providing EPT or RVI).

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

HISTORY
The vmm driver appeared in OpenBSD 5.9.

AUTHORS
Mike Larkin <mlarkin@openbsd.org>