kvm_rs/
kvm.rs

1// SPDX-License-Identifier: MIT
2//
3// Copyright (c) 2021, Johannes Stoelp <dev@memzero.de>
4
5//! KVM system ioctls.
6
7use std::fs;
8use std::io;
9use std::os::unix::io::FromRawFd;
10
11use crate::cap::{CapBool, CapInt};
12use crate::vm::Vm;
13use crate::{ioctl, kvm_sys, libcret};
14
15/// Wrapper for `/dev/kvm` ioctls.
16///
17/// Representation of the file descriptor obtained by opening `/dev/kvm`.
18/// This wrapper provides access to the `system ioctls` as described in [KVM API][kvm].
19///
20/// [kvm]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#general-description
21pub struct Kvm {
22    kvm: fs::File,
23}
24
25impl Kvm {
26    /// Open the `/dev/kvm` device.
27    pub fn new() -> io::Result<Kvm> {
28        let kvm = libcret(unsafe {
29            libc::open("/dev/kvm\0".as_ptr().cast(), libc::O_RDWR | libc::O_CLOEXEC)
30        })
31        .map(|fd| unsafe { fs::File::from_raw_fd(fd) })?;
32
33        assert_eq!(
34            kvm_sys::KVM_API_VERSION,
35            ioctl(&kvm, kvm_sys::KVM_GET_API_VERSION, 0)?
36        );
37
38        Ok(Kvm { kvm })
39    }
40
41    fn get_vpcu_mmap_size(&self) -> io::Result<usize> {
42        ioctl(&self.kvm, kvm_sys::KVM_GET_VCPU_MMAP_SIZE, 0).map(|size| size as usize)
43    }
44
45    /// Create a new virtual machine with the [`KVM_CREATE_VM`][kvm-create-vm] ioctl.
46    /// Returns a wrapper [`vm::Vm`][crate::vm::Vm] representing the VM.
47    ///
48    /// [kvm-create-vm]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-create-vm
49    pub fn create_vm(&self) -> io::Result<Vm> {
50        let vm = ioctl(&self.kvm, kvm_sys::KVM_CREATE_VM, 0 /* machine id */)
51            .map(|fd| unsafe { fs::File::from_raw_fd(fd) })?;
52
53        let vcpu_mmap_size = self.get_vpcu_mmap_size()?;
54
55        Ok(Vm::new(vm, vcpu_mmap_size))
56    }
57
58    /// Check availability of an extension with the [`KVM_CHECK_EXTENSION`][kvm-check-extension]
59    /// ioctl.
60    ///
61    /// [kvm-check-extension]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-check-extension
62    pub fn check_extenstion(&self, cap: CapBool) -> bool {
63        let ret = ioctl(&self.kvm, kvm_sys::KVM_CHECK_EXTENSION, cap.into());
64
65        matches!(ret, Ok(ret) if ret > 0)
66    }
67
68    /// Check availability of an extension with the [`KVM_CHECK_EXTENSION`][kvm-check-extension]
69    /// ioctl.
70    ///
71    /// [kvm-check-extension]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-check-extension
72    pub fn check_extenstion_int(&self, cap: CapInt) -> i32 {
73        let ret = ioctl(&self.kvm, kvm_sys::KVM_CHECK_EXTENSION, cap.into());
74
75        ret.unwrap_or(0)
76    }
77}
kvm_rs/kvm.rs

kvm_rs/
kvm.rs
