VMM(4)                 FreeBSD Kernel Interfaces Manual                 VMM(4)

NAME

     vmm.ko - bhyve virtual machine monitor

SYNOPSIS

     To load the driver as a module at boot, add this line to loader.conf(5):

           vmm_load="YES"

     The module can also be loaded manually with kldload(8):

           kldload vmm

DESCRIPTION

     vmm.ko provides the kernel portion of the bhyve(4) hypervisor.  The
     following platforms are supported:

     o   amd64: An Intel CPU with VT-x/EPT or AMD CPU with SVM support is
         required.

     o   arm64: The boot CPU must start in EL2 and the system must have a
         GICv3 interrupt controller.  VHE support will be used if available.

     o   riscv: The CPUs must implement the H (hypervisor) RISC-V ISA
         extension.

     PCI device passthrough to a virtual machine requires hardware with VT-d
     support and is available only on amd64.

PCI PASSTHROUGH

     On amd64 where the hardware supports VT-d, PCI devices can be reserved
     for use by the hypervisor.  Entries consisting of the PCI
     bus/slot/function are added to the pptdevs loader.conf(5) variable.
     Additional entries are separated by spaces.  Host PCI devices that match
     an entry will be assigned to the hypervisor and will not be probed by
     FreeBSD device drivers.  See the EXAMPLES section below for sample usage.

     Note that vmm must be given first the right of refusal to all pci(4)
     devices it may need to claim.  As a result, the vmm kernel module almost
     certainly needs to be loaded from loader.conf(5) rather than by adding it
     to kld_list in rc.conf(5).

     A large number of PCI device entries may require a string longer than the
     128-character limit of loader.conf(5) variables.  The pptdevs2 and
     pptdevs3 variables can be used for additional entries.

LOADER TUNABLES

     Tunables can be set at the loader(8) prompt before booting the kernel or
     stored in loader.conf(5).

     hw.vmm.maxcpu
             Maximum number of virtual CPUs.  The default is the number of
             physical CPUs in the system.

EXAMPLES

     Reserve three PCI devices for use by the hypervisor: bus 10 slot 0
     function 0, bus 6 slot 5 function 0, and bus 6 slot 5 function 1.

           pptdevs="10/0/0 6/5/0 6/5/1"

     It is possible to detach ppt from a PCI device without rebooting the host
     machine and then attach a host driver, using the devctl(8) utility.
     Suppose ppt is currently attached to pci0:0:1:0 and we want the host's
     xhci(4) driver to be attached instead:

           # devctl set driver -f pci0:0:1:0 xhci

     The same can be applied to attach ppt back:

           # devctl set driver -f pci0:0:1:0 ppt

SEE ALSO

     bhyve(4), loader.conf(5), bhyve(8), bhyveload(8), devctl(8), kldload(8)

HISTORY

     vmm.ko first appeared in FreeBSD 10.0.  arm64 and riscv support first
     appeared in FreeBSD 15.0.

AUTHORS

     Neel Natu <neel@freebsd.org>
     Peter Grehan <grehan@freebsd.org>

FreeBSD 15.1-STABLE-HBSD       December 30, 2024                        VMM(4)