Awesome

memflow's KVM connector and its driver

This is a connector for Kernel based virtual machines, by using a driver that maps all KVM pages into the memflow process (userspace -> userspace DMA).

memflow-kmod includes the kernel module that performs the operations.

memflow-kvm-ioctl provides a rust based IOCTL api to the kernel module.

memflow-kvm provides a memflow physical memory connector that uses the ioctl.

Setup

Connector

Recommended way is to use memflowup.

Kernel module

Your kernel must be compiled with CONFIG_KALLSYMS=y, and CONFIG_KALLSYMS_ALL=y being set in kconfig.

By default memflowup will install the latest kernel module automatically.

Stable versions are available under releases.

Debian/Ubuntu package can be installed with sudo dpkg -i memflow-dkms_${VERSION}_amd64.deb, where VERSION is the version of the downloaded module.

For other distributions, run this command:

sudo dkms install --archive=memflow-${VERSION}-source-only.dkms.tar.gz

It might be necessary to also load the module at runtime:

modprobe memflow

To load the module at startup create a new file in /etc/modules-load.d/:

/etc/modules-load.d/memflow-kvm.conf
---
# Load memflow-kvm module on startup
memflow

The simplest way to setup the kernel module is to create a new group called memflow and use a udev rule to set access rights to /dev/memflow automatically when the module is being loaded:

groupadd memflow
usermod -a -G memflow $USER

Then create the udev rule in /etc/udev/rules.d/:

/etc/udev/rules.d/99-memflow-kvm.rules
---
KERNEL=="memflow" SUBSYSTEM=="misc" GROUP="memflow" MODE="0660"

Manual installation

Connector

Install the connector using memflowup build --name memflow-kvm. This will compile the connector in release mode and place it under ~/.local/lib/memflow/ directory, which can then be accessed by memflow clients. Do copy out the underlying shared library to /usr/local/lib/memflow/ if you want to use it across all users.

Kernel module

Initialize submodules:

git submodule update --init

Run make. output will be placed in memflow-kmod/memflow.ko.

Then to install the module:

source dkms.conf
sudo mkdir /usr/src/$BUILT_MODULE_NAME-$PACKAGE_VERSION
sudo cp -r * /usr/src/$BUILT_MODULE_NAME-$PACKAGE_VERSION
sudo dkms build -m $BUILT_MODULE_NAME -v $PACKAGE_VERSION
sudo dkms install -m $BUILT_MODULE_NAME -v $PACKAGE_VERSION

Then you can load the module:

sudo modprobe memflow

FAQ

Q. I'm getting this warning:

warning: couldn't execute `llvm-config --prefix` (error: No such file or directory (os error 2))
warning: set the LLVM_CONFIG_PATH environment variable to the full path to a valid `llvm-config` executable (including the executable itself)

A. This warning is harmless and can be safely ignored.

Licensing note

While memflow-kvm-ioctl, and memflow-kvm are licensed under the MIT license, memflow-kmod is licensed only under GPL-2.