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//! KVM system ioctls.
use std::fs;
use std::io;
use std::os::unix::io::FromRawFd;
use crate::{libcret, ioctl, kvm_sys};
use crate::vm::Vm;
/// Wrapper for `/dev/kvm` ioctls.
///
/// Representation of the file descriptor obtained by opening `/dev/kvm`.
/// This wrapper provides access to the `system ioctls` as described in [KVM API][kvm].
///
/// [kvm]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#general-description
pub struct Kvm {
kvm: fs::File,
}
impl Kvm {
/// Open the `/dev/kvm` device.
pub fn new() -> io::Result<Kvm> {
let kvm = libcret(unsafe {
libc::open("/dev/kvm\0".as_ptr().cast(), libc::O_RDWR | libc::O_CLOEXEC)
})
.map(|fd| unsafe { fs::File::from_raw_fd(fd) })?;
assert_eq!(
kvm_sys::KVM_API_VERSION,
ioctl(&kvm, kvm_sys::KVM_GET_API_VERSION, 0)?
);
Ok(Kvm { kvm })
}
fn get_vpcu_mmap_size(&self) -> io::Result<usize> {
ioctl(&self.kvm, kvm_sys::KVM_GET_VCPU_MMAP_SIZE, 0).map(|size| size as usize)
}
/// Create a new virtual machine with the [`KVM_CREATE_VM`][kvm-create-vm] ioctl.
/// Returns a wrapper [`vm::Vm`][crate::vm::Vm] representing the VM.
///
/// [kvm-create-vm]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-create-vm
pub fn create_vm(&self) -> io::Result<Vm> {
let vm = ioctl(&self.kvm, kvm_sys::KVM_CREATE_VM, 0 /* machine id */)
.map(|fd| unsafe { fs::File::from_raw_fd(fd) })?;
let vcpu_mmap_size = self.get_vpcu_mmap_size()?;
Ok(Vm::new(vm, vcpu_mmap_size))
}
}
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