linux/drivers/vhost/Kconfig
Mike Christie e297cd54b3
vhost_task: Allow vhost layer to use copy_process
Qemu will create vhost devices in the kernel which perform network, SCSI,
etc IO and management operations from worker threads created by the
kthread API. Because the kthread API does a copy_process on the kthreadd
thread, the vhost layer has to use kthread_use_mm to access the Qemu
thread's memory and cgroup_attach_task_all to add itself to the Qemu
thread's cgroups, and it bypasses the RLIMIT_NPROC limit which can result
in VMs creating more threads than the admin expected.

This patch adds a new struct vhost_task which can be used instead of
kthreads. They allow the vhost layer to use copy_process and inherit
the userspace process's mm and cgroups, the task is accounted for
under the userspace's nproc count and can be seen in its process tree,
and other features like namespaces work and are inherited by default.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-03-23 12:45:36 +01:00

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# SPDX-License-Identifier: GPL-2.0-only
config VHOST_IOTLB
tristate
help
Generic IOTLB implementation for vhost and vringh.
This option is selected by any driver which needs to support
an IOMMU in software.
config VHOST_RING
tristate
select VHOST_IOTLB
help
This option is selected by any driver which needs to access
the host side of a virtio ring.
config VHOST_TASK
bool
default n
config VHOST
tristate
select VHOST_IOTLB
select VHOST_TASK
help
This option is selected by any driver which needs to access
the core of vhost.
menuconfig VHOST_MENU
bool "VHOST drivers"
default y
if VHOST_MENU
config VHOST_NET
tristate "Host kernel accelerator for virtio net"
depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP)
select VHOST
help
This kernel module can be loaded in host kernel to accelerate
guest networking with virtio_net. Not to be confused with virtio_net
module itself which needs to be loaded in guest kernel.
To compile this driver as a module, choose M here: the module will
be called vhost_net.
config VHOST_SCSI
tristate "VHOST_SCSI TCM fabric driver"
depends on TARGET_CORE && EVENTFD
select VHOST
default n
help
Say M here to enable the vhost_scsi TCM fabric module
for use with virtio-scsi guests
config VHOST_VSOCK
tristate "vhost virtio-vsock driver"
depends on VSOCKETS && EVENTFD
select VHOST
select VIRTIO_VSOCKETS_COMMON
default n
help
This kernel module can be loaded in the host kernel to provide AF_VSOCK
sockets for communicating with guests. The guests must have the
virtio_transport.ko driver loaded to use the virtio-vsock device.
To compile this driver as a module, choose M here: the module will be called
vhost_vsock.
config VHOST_VDPA
tristate "Vhost driver for vDPA-based backend"
depends on EVENTFD
select VHOST
select IRQ_BYPASS_MANAGER
depends on VDPA
help
This kernel module can be loaded in host kernel to accelerate
guest virtio devices with the vDPA-based backends.
To compile this driver as a module, choose M here: the module
will be called vhost_vdpa.
config VHOST_CROSS_ENDIAN_LEGACY
bool "Cross-endian support for vhost"
default n
help
This option allows vhost to support guests with a different byte
ordering from host while using legacy virtio.
Userspace programs can control the feature using the
VHOST_SET_VRING_ENDIAN and VHOST_GET_VRING_ENDIAN ioctls.
This is only useful on a few platforms (ppc64 and arm64). Since it
adds some overhead, it is disabled by default.
If unsure, say "N".
endif