Add support for Windows by using WHP with libkrun 2.0

Cargo.toml

@@ -16,8 +16,16 @@ sysinfo = "0.31.4"
 log = "0.4.0"
 env_logger = "0.11.8"
 regex = "1.11.1"
+[target.'cfg(target_os = "macos")'.dependencies]
 core-foundation = "0.10.1"
 objc2-io-kit = "0.3.2"
 httparse = "1.10.1"
 serde = { version = "1.0.228", features = ["derive"] }
 serde_json = "1.0.150"
+
+[target.'cfg(target_os = "windows")'.dependencies]
+windows-sys = { version = "0.61.2", features = [
+    "Win32_Foundation",
+    "Win32_Networking_WinSock",
+    "Win32_System_Console",
+] }

README.md

@@ -3,7 +3,7 @@
 `krunkit` is a tool to launch configurable virtual machines using the [libkrun](https://github.com/containers/libkrun) platform.
 
 > [!IMPORTANT]
-> krunkit is only supported on hosts running macOS 14 or newer.
+> The established krunkit path supports macOS 14 or newer. Experimental Windows support uses libkrun 2.0 and WHP.
 
 ## Installation
 
@@ -39,6 +39,14 @@ make
 sudo make install
 ```
 
+On Windows, `LIBKRUN_LIB_DIR` must point to the directory containing `krun.dll.lib` when invoking Cargo.
+Place the matching `krun.dll` beside `krunkit.exe` to run it. For local development, `build.ps1` builds a
+libkrun 2.0 tree and copies its DLL beside the executable:
+
+```powershell
+.\build.ps1 -LibkrunSource C:\src\libkrun
+```
+
 To build with `libkrun` from *Homebrew* or *MacPorts* use the appropriate `PREFIX`:
 
 ```

build.ps1

@@ -0,0 +1,66 @@
+param (
+    [ValidateSet("all", "debug", "install", "clean")]
+    [string]$Task = "all",
+
+    [string]$Prefix = $env:PREFIX,
+
+    [string]$LibkrunSource = $env:LIBKRUN_SOURCE_DIR
+)
+
+$ErrorActionPreference = "Stop"
+$BinName      = "krunkit.exe"
+$ReleasePath  = "target\release\$BinName"
+$DebugPath    = "target\debug\$BinName"
+
+function Build-Krunkit([string]$Profile) {
+    if ([string]::IsNullOrWhiteSpace($LibkrunSource)) {
+        throw "Specify -LibkrunSource or set LIBKRUN_SOURCE_DIR"
+    }
+
+    $ReleaseArg = @()
+    if ($Profile -eq "release") {
+        $ReleaseArg += "--release"
+    }
+    cargo build --manifest-path (Join-Path $LibkrunSource "Cargo.toml") -p libkrun --features "ffi blk net" @ReleaseArg
+    if ($LASTEXITCODE -ne 0) { throw "libkrun build failed" }
+
+    $env:LIBKRUN_LIB_DIR = Join-Path $LibkrunSource "target\$Profile"
+    cargo build @ReleaseArg
+    if ($LASTEXITCODE -ne 0) { throw "krunkit build failed" }
+
+    Copy-Item -Path (Join-Path $env:LIBKRUN_LIB_DIR "krun.dll") -Destination "target\$Profile\krun.dll" -Force
+}
+
+switch ($Task) {
+    "all" {
+        Build-Krunkit "release"
+    }
+
+    "debug" {
+        Build-Krunkit "debug"
+    }
+
+    "install" {
+        if ([string]::IsNullOrWhiteSpace($Prefix)) {
+            throw "Specify -Prefix or set PREFIX"
+        }
+
+        if (-not (Test-Path $ReleasePath)) {
+            Build-Krunkit "release"
+        }
+
+        $TargetBinDir = Join-Path $Prefix "bin"
+
+        if (-not (Test-Path $TargetBinDir)) {
+            New-Item -ItemType Directory -Path $TargetBinDir -Force | Out-Null
+        }
+
+        Copy-Item -Path $ReleasePath -Destination $TargetBinDir -Force
+        Copy-Item -Path "target\release\krun.dll" -Destination $TargetBinDir -Force
+        Write-Host "Successfully installed to: $TargetBinDir" -ForegroundColor Green
+    }
+
+    "clean" {
+        cargo clean
+    }
+}

build.rs

@@ -1,4 +1,4 @@
-// SDPX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: Apache-2.0
 
 fn main() {
     #[cfg(target_os = "macos")]
@@ -11,4 +11,13 @@ fn main() {
 
         println!("cargo:rerun-if-env-changed=PREFIX");
     }
+
+    #[cfg(target_os = "windows")]
+    {
+        let lib_dir = std::env::var("LIBKRUN_LIB_DIR")
+            .expect("LIBKRUN_LIB_DIR must point to the directory containing krun.dll.lib");
+        println!("cargo:rustc-link-search={lib_dir}");
+
+        println!("cargo:rerun-if-env-changed=LIBKRUN_LIB_DIR");
+    }
 }

docs/usage.md

@@ -1,7 +1,8 @@
 # krunkit Command Line
 
-`krunkit` can launch configurable virtual machines using macOS's hypervisor framework and the `libkrun` virtual
-machine monitor library. The `libkrun` virtual machine configuration can be specified from command line arguments.
+`krunkit` can launch configurable virtual machines using macOS's hypervisor framework or Windows Hypervisor
+Platform and the `libkrun` virtual machine monitor library. The `libkrun` virtual machine configuration can be 
+specified from command line arguments.
 
 Specifying a virtual machine's vCPU and RAM allocation is required. Adding devices is optional, yet most workloads
 will require a root disk to be useful.
@@ -64,11 +65,9 @@ This configures a virtual machine to use two vCPUs and 2048 MiB of RAM:
 --cpus 2 --memory 2048
 ```
 
-## Bootloader Configuration
-
 ### EFI bootloader
 
-`--bootloader efi` allows booting a disk image using EFI, which removes the need for providing external kernel/initrd/... jthe disk image bootloader will be started by the EFI firmware, which will in turn know which kernel it should be booting.
+`--bootloader efi` allows booting a disk image using EFI, which removes the need for providing external kernel/initrd/... the disk image bootloader will be started by the EFI firmware, which will in turn know which kernel it should be booting.
 
 #### Arguments
 - `variable-store`: path to a file which EFI can use to store its variables
@@ -271,3 +270,71 @@ The table below provides some data on how offloading effects the gvproxy and vmn
 | gvproxy       | krunkit  | false      |  1.47 Gbits/s |  2.58 Gbits/s |
 | gvproxy       | vfkit    | false      |  1.43 Gbits/s |  2.84 Gbits/s |
 
+## Bootloader Configuration on Windows
+
+On Windows, krunkit boots `edk2/OVMF.fd` by default. Use `--firmware-path PATH` to select another UEFI image.
+
+The Windows path connects `ttyS0` to the host terminal. It supports raw and QCOW2 `virtio-blk` images,
+path-based `virtio-net,type=unixstream` devices, and `virtio-vsock` Unix socket mappings.
+
+### Windows Limitations
+
+On Windows, only the following devices can be specified with `--device`:
+
+- `virtio-blk`
+- `virtio-net,type=unixstream,path=...`; `unixgram`, `unixSocketPath`, and `fd` backends are unsupported.
+- `virtio-vsock`
+- `virtio-fs` (requires `permissionSemantics=complete`; `simplified` is not supported on Windows)
+
+`virtio-serial`, `virtio-gpu`, and `virtio-input` are unsupported. `virtio-rng` is added
+automatically, but must not be specified with `--device`.
+
+The RESTful service (`--restful-uri`), `--timesync`, and nested virtualization (`--nested`) are not
+supported on Windows. The default console is connected directly to the host terminal; use it instead of a
+`virtio-serial` device for guest text output.
+
+```powershell
+krunkit.exe --cpus 2 --memory 2G `
+  --firmware-path C:\vm\OVMF.fd `
+  --device virtio-blk,path=C:\vm\disk.raw,format=raw
+```
+
+### SSH on Windows
+
+Start gvproxy in a separate terminal. Its default virtual network assigns the guest `192.168.127.2`, and
+`-ssh-port 2222` forwards host port 2222 to guest port 22:
+
+```powershell
+gvproxy.exe -listen-qemu unix://C:/vm/network.sock -ssh-port 2222
+```
+
+Add the matching network device when starting krunkit:
+
+```powershell
+krunkit.exe --cpus 2 --memory 2G `
+  --firmware-path C:\vm\OVMF.fd `
+  --device virtio-blk,path=C:\vm\rootfs.raw,format=raw `
+  --device virtio-net,type=unixstream,path=C:\vm\network.sock,mac=5a:94:ef:e4:0c:ee,offloading=true
+```
+
+The guest must run DHCP on the virtio network interface and have `sshd` listening on port 22. Connect with:
+
+```powershell
+ssh.exe -p 2222 USER@127.0.0.1
+```
+
+### vsock on Windows
+
+The default `listen` action handles guest-initiated connections: libkrun connects guest port 1024 to an existing
+host Unix socket.
+
+```powershell
+--device virtio-vsock,port=1024,socketURL=C:\vm\guest-to-host.sock,listen
+```
+
+Use `connect` for host-initiated connections. Libkrun listens at the host socket path and forwards accepted
+connections to a service listening on guest CID 3, port 1024.
+
+```powershell
+--device virtio-vsock,port=1024,socketURL=C:\vm\host-to-guest.sock,connect
+```

src/context/mod.rs

@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#[cfg(not(windows))]
+mod unix;
+#[cfg(windows)]
+mod windows;
+
+#[cfg(not(windows))]
+pub use unix::KrunContext;
+#[cfg(windows)]
+pub use windows::KrunContext;

src/context.rs → src/context/unix.rs

@@ -1,8 +1,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
-use super::*;
-
 use crate::{
+    cmdline::Args,
     status::{get_shutdown_eventfd, status_listener, RestfulUri},
     virtio::KrunContextSet,
 };
@@ -16,7 +15,9 @@ use std::{
     io,
 };
 
+#[cfg(target_os = "macos")]
 use crate::timesync::timesync_listener;
+#[cfg(target_os = "macos")]
 use crate::virtio::{VsockAction, VsockConfig};
 use anyhow::{anyhow, Context};
 use env_logger::{Builder, Env, Target};
@@ -199,6 +200,7 @@ impl TryFrom<Args> for KrunContext {
             }
         }
 
+        #[cfg(target_os = "macos")]
         if let Some(timesync_port) = args.timesync {
             let vsock_config = VsockConfig {
                 port: timesync_port,