Linux v6.6.1 - xen
# SPDX-License-Identifier: GPL-2.0-only
menu "Xen driver support"
depends on XEN
config XEN_BALLOON
bool "Xen memory balloon driver"
default y
help
The balloon driver allows the Xen domain to request more memory from
the system to expand the domain's memory allocation, or alternatively
return unneeded memory to the system.
config XEN_BALLOON_MEMORY_HOTPLUG
bool "Memory hotplug support for Xen balloon driver"
depends on XEN_BALLOON && MEMORY_HOTPLUG
default y
help
Memory hotplug support for Xen balloon driver allows expanding memory
available for the system above limit declared at system startup.
It is very useful on critical systems which require long
run without rebooting.
It's also very useful for non PV domains to obtain unpopulated physical
memory ranges to use in order to map foreign memory or grants.
Memory could be hotplugged in following steps:
1) target domain: ensure that memory auto online policy is in
effect by checking /sys/devices/system/memory/auto_online_blocks
file (should be 'online').
2) control domain: xl mem-max <target-domain> <maxmem>
where <maxmem> is >= requested memory size,
3) control domain: xl mem-set <target-domain> <memory>
where <memory> is requested memory size; alternatively memory
could be added by writing proper value to
/sys/devices/system/xen_memory/xen_memory0/target or
/sys/devices/system/xen_memory/xen_memory0/target_kb on the
target domain.
Alternatively, if memory auto onlining was not requested at step 1
the newly added memory can be manually onlined in the target domain
by doing the following:
for i in /sys/devices/system/memory/memory*/state; do \
[ "`cat "$i"`" = offline ] && echo online > "$i"; done
or by adding the following line to udev rules:
SUBSYSTEM=="memory", ACTION=="add", RUN+="/bin/sh -c '[ -f /sys$devpath/state ] && echo online > /sys$devpath/state'"
config XEN_MEMORY_HOTPLUG_LIMIT
int "Hotplugged memory limit (in GiB) for a PV guest"
default 512
depends on XEN_HAVE_PVMMU
depends on MEMORY_HOTPLUG
help
Maximum amount of memory (in GiB) that a PV guest can be
expanded to when using memory hotplug.
A PV guest can have more memory than this limit if is
started with a larger maximum.
This value is used to allocate enough space in internal
tables needed for physical memory administration.
config XEN_SCRUB_PAGES_DEFAULT
bool "Scrub pages before returning them to system by default"
depends on XEN_BALLOON
default y
help
Scrub pages before returning them to the system for reuse by
other domains. This makes sure that any confidential data
is not accidentally visible to other domains. It is more
secure, but slightly less efficient. This can be controlled with
xen_scrub_pages=0 parameter and
/sys/devices/system/xen_memory/xen_memory0/scrub_pages.
This option only sets the default value.
If in doubt, say yes.
config XEN_DEV_EVTCHN
tristate "Xen /dev/xen/evtchn device"
default y
help
The evtchn driver allows a userspace process to trigger event
channels and to receive notification of an event channel
firing.
If in doubt, say yes.
config XEN_BACKEND
bool "Backend driver support"
default XEN_DOM0
help
Support for backend device drivers that provide I/O services
to other virtual machines.
config XENFS
tristate "Xen filesystem"
select XEN_PRIVCMD
default y
help
The xen filesystem provides a way for domains to share
information with each other and with the hypervisor.
For example, by reading and writing the "xenbus" file, guests
may pass arbitrary information to the initial domain.
If in doubt, say yes.
config XEN_COMPAT_XENFS
bool "Create compatibility mount point /proc/xen"
depends on XENFS
default y
help
The old xenstore userspace tools expect to find "xenbus"
under /proc/xen, but "xenbus" is now found at the root of the
xenfs filesystem. Selecting this causes the kernel to create
the compatibility mount point /proc/xen if it is running on
a xen platform.
If in doubt, say yes.
config XEN_SYS_HYPERVISOR
bool "Create xen entries under /sys/hypervisor"
depends on SYSFS
select SYS_HYPERVISOR
default y
help
Create entries under /sys/hypervisor describing the Xen
hypervisor environment. When running native or in another
virtual environment, /sys/hypervisor will still be present,
but will have no xen contents.
config XEN_XENBUS_FRONTEND
tristate
config XEN_GNTDEV
tristate "userspace grant access device driver"
depends on XEN
default m
select MMU_NOTIFIER
help
Allows userspace processes to use grants.
config XEN_GNTDEV_DMABUF
bool "Add support for dma-buf grant access device driver extension"
depends on XEN_GNTDEV && XEN_GRANT_DMA_ALLOC
select DMA_SHARED_BUFFER
help
Allows userspace processes and kernel modules to use Xen backed
dma-buf implementation. With this extension grant references to
the pages of an imported dma-buf can be exported for other domain
use and grant references coming from a foreign domain can be
converted into a local dma-buf for local export.
config XEN_GRANT_DEV_ALLOC
tristate "User-space grant reference allocator driver"
depends on XEN
default m
help
Allows userspace processes to create pages with access granted
to other domains. This can be used to implement frontend drivers
or as part of an inter-domain shared memory channel.
config XEN_GRANT_DMA_ALLOC
bool "Allow allocating DMA capable buffers with grant reference module"
depends on XEN && HAS_DMA
help
Extends grant table module API to allow allocating DMA capable
buffers and mapping foreign grant references on top of it.
The resulting buffer is similar to one allocated by the balloon
driver in that proper memory reservation is made by
({increase|decrease}_reservation and VA mappings are updated if
needed).
This is useful for sharing foreign buffers with HW drivers which
cannot work with scattered buffers provided by the balloon driver,
but require DMAable memory instead.
config SWIOTLB_XEN
def_bool y
depends on XEN_PV || ARM || ARM64
select DMA_OPS
select SWIOTLB
config XEN_PCI_STUB
bool
config XEN_PCIDEV_STUB
tristate "Xen PCI-device stub driver"
depends on PCI && !X86 && XEN
depends on XEN_BACKEND
select XEN_PCI_STUB
default m
help
The PCI device stub driver provides limited version of the PCI
device backend driver without para-virtualized support for guests.
If you select this to be a module, you will need to make sure no
other driver has bound to the device(s) you want to make visible to
other guests.
The "hide" parameter (only applicable if backend driver is compiled
into the kernel) allows you to bind the PCI devices to this module
from the default device drivers. The argument is the list of PCI BDFs:
xen-pciback.hide=(03:00.0)(04:00.0)
If in doubt, say m.
config XEN_PCIDEV_BACKEND
tristate "Xen PCI-device backend driver"
depends on PCI && X86 && XEN
depends on XEN_BACKEND
select XEN_PCI_STUB
default m
help
The PCI device backend driver allows the kernel to export arbitrary
PCI devices to other guests. If you select this to be a module, you
will need to make sure no other driver has bound to the device(s)
you want to make visible to other guests.
The parameter "passthrough" allows you specify how you want the PCI
devices to appear in the guest. You can choose the default (0) where
PCI topology starts at 00.00.0, or (1) for passthrough if you want
the PCI devices topology appear the same as in the host.
The "hide" parameter (only applicable if backend driver is compiled
into the kernel) allows you to bind the PCI devices to this module
from the default device drivers. The argument is the list of PCI BDFs:
xen-pciback.hide=(03:00.0)(04:00.0)
If in doubt, say m.
config XEN_PVCALLS_FRONTEND
tristate "XEN PV Calls frontend driver"
depends on INET && XEN
select XEN_XENBUS_FRONTEND
help
Experimental frontend for the Xen PV Calls protocol
(https://xenbits.xen.org/docs/unstable/misc/pvcalls.html). It
sends a small set of POSIX calls to the backend, which
implements them.
config XEN_PVCALLS_BACKEND
tristate "XEN PV Calls backend driver"
depends on INET && XEN && XEN_BACKEND
help
Experimental backend for the Xen PV Calls protocol
(https://xenbits.xen.org/docs/unstable/misc/pvcalls.html). It
allows PV Calls frontends to send POSIX calls to the backend,
which implements them.
If in doubt, say n.
config XEN_SCSI_BACKEND
tristate "XEN SCSI backend driver"
depends on XEN && XEN_BACKEND && TARGET_CORE
help
The SCSI backend driver allows the kernel to export its SCSI Devices
to other guests via a high-performance shared-memory interface.
Only needed for systems running as XEN driver domains (e.g. Dom0) and
if guests need generic access to SCSI devices.
config XEN_PRIVCMD
tristate "Xen hypercall passthrough driver"
depends on XEN
default m
help
The hypercall passthrough driver allows privileged user programs to
perform Xen hypercalls. This driver is normally required for systems
running as Dom0 to perform privileged operations, but in some
disaggregated Xen setups this driver might be needed for other
domains, too.
config XEN_PRIVCMD_IRQFD
bool "Xen irqfd support"
depends on XEN_PRIVCMD && XEN_VIRTIO && EVENTFD
help
Using the irqfd mechanism a virtio backend running in a daemon can
speed up interrupt injection into a guest.
config XEN_ACPI_PROCESSOR
tristate "Xen ACPI processor"
depends on XEN && XEN_PV_DOM0 && X86 && ACPI_PROCESSOR && CPU_FREQ
default m
help
This ACPI processor uploads Power Management information to the Xen
hypervisor.
To do that the driver parses the Power Management data and uploads
said information to the Xen hypervisor. Then the Xen hypervisor can
select the proper Cx and Pxx states. It also registers itself as the
SMM so that other drivers (such as ACPI cpufreq scaling driver) will
not load.
To compile this driver as a module, choose M here: the module will be
called xen_acpi_processor If you do not know what to choose, select
M here. If the CPUFREQ drivers are built in, select Y here.
config XEN_MCE_LOG
bool "Xen platform mcelog"
depends on XEN_PV_DOM0 && X86_MCE
help
Allow kernel fetching MCE error from Xen platform and
converting it into Linux mcelog format for mcelog tools
config XEN_HAVE_PVMMU
bool
config XEN_EFI
def_bool y
depends on (ARM || ARM64 || X86_64) && EFI
config XEN_AUTO_XLATE
def_bool y
depends on ARM || ARM64 || XEN_PVHVM
help
Support for auto-translated physmap guests.
config XEN_ACPI
def_bool y
depends on X86 && ACPI
config XEN_SYMS
bool "Xen symbols"
depends on X86 && XEN_DOM0 && XENFS
default y if KALLSYMS
help
Exports hypervisor symbols (along with their types and addresses) via
/proc/xen/xensyms file, similar to /proc/kallsyms
config XEN_HAVE_VPMU
bool
config XEN_FRONT_PGDIR_SHBUF
tristate
config XEN_UNPOPULATED_ALLOC
bool "Use unpopulated memory ranges for guest mappings"
depends on ZONE_DEVICE
default XEN_BACKEND || XEN_GNTDEV || XEN_DOM0
help
Use unpopulated memory ranges in order to create mappings for guest
memory regions, including grant maps and foreign pages. This avoids
having to balloon out RAM regions in order to obtain physical memory
space to create such mappings.
config XEN_GRANT_DMA_IOMMU
bool
select IOMMU_API
config XEN_GRANT_DMA_OPS
bool
select DMA_OPS
config XEN_VIRTIO
bool "Xen virtio support"
depends on VIRTIO
select XEN_GRANT_DMA_OPS
select XEN_GRANT_DMA_IOMMU if OF
help
Enable virtio support for running as Xen guest. Depending on the
guest type this will require special support on the backend side
(qemu or kernel, depending on the virtio device types used).
If in doubt, say n.
config XEN_VIRTIO_FORCE_GRANT
bool "Require Xen virtio support to use grants"
depends on XEN_VIRTIO
help
Require virtio for Xen guests to use grant mappings.
This will avoid the need to give the backend the right to map all
of the guest memory. This will need support on the backend side
(e.g. qemu or kernel, depending on the virtio device types used).
endmenu