1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

//! VCPU system ioctls.

use std::fs;
use std::io;

use crate::{ioctl, kvm_sys, KvmRun};

/// Exit reasons for the [`Vcpu::run`][crate::vcpu::Vcpu::run] function.
///
/// Details for the different exit reasons can be found in the [`kvm_run`
/// structure][kvm-run-struct] description.
///
/// [kvm-run]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-run
/// [kvm-run-struct]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#the-kvm-run-structure
pub enum KvmExit<'cpu> {
    Halt,
    IoIn(u16, &'cpu mut [u8]),
    IoOut(u16, &'cpu [u8]),
    MmioRead(u64, &'cpu mut [u8]),
    MmioWrite(u64, &'cpu [u8]),
}

/// Wrapper for VCPU ioctls.
///
/// Representation of the file descriptor obtained by the [`KVM_CREATE_VCPU`][kvm-create-vcpu] ioctl.
/// This wrapper provides access to the `VCPU ioctls` as described in [KVM API][kvm].
///
/// [kvm]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#general-description
/// [kvm-create-vcpu]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-create-vcpu
pub struct Vcpu {
    vcpu: fs::File,
    kvm_run: KvmRun,
}

impl Vcpu {
    pub(crate) fn new(vcpu: fs::File, kvm_run: KvmRun) -> Vcpu {
        Vcpu { vcpu, kvm_run }
    }

    /// Get the general purpose registers with the [`KVM_GET_REGS`][kvm-get-regs] ioctl in form of
    /// [`kvm_regs`](crate::kvm_sys::kvm_regs).
    ///
    /// [kvm-get-regs]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-get-regs
    pub fn get_regs(&self) -> io::Result<kvm_sys::kvm_regs> {
        let mut regs = kvm_sys::kvm_regs::default();
        ioctl(
            &self.vcpu,
            kvm_sys::KVM_GET_REGS,
            &mut regs as *mut _ as u64,
        )?;
        Ok(regs)
    }

    /// Set the general purpose registers with the [`KVM_SET_REGS`][kvm-set-regs] ioctl in form of
    /// [`kvm_regs`](crate::kvm_sys::kvm_regs).
    ///
    /// [kvm-set-regs]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-set-regs
    pub fn set_regs(&self, regs: kvm_sys::kvm_regs) -> io::Result<()> {
        ioctl(&self.vcpu, kvm_sys::KVM_SET_REGS, &regs as *const _ as u64).map(|_| ())
    }

    /// Get the special registers with the [`KVM_GET_SREGS`][kvm-get-sregs] ioctl in form of
    /// [`kvm_sregs`](crate::kvm_sys::kvm_sregs).
    ///
    /// [kvm-get-sregs]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-get-sregs
    pub fn get_sregs(&self) -> io::Result<kvm_sys::kvm_sregs> {
        let mut sregs = kvm_sys::kvm_sregs::default();
        ioctl(
            &self.vcpu,
            kvm_sys::KVM_GET_SREGS,
            &mut sregs as *mut _ as u64,
        )?;
        Ok(sregs)
    }

    /// Set the special registers with the [`KVM_SET_SREGS`][kvm-set-sregs] ioctl in form of
    /// [`kvm_sregs`](crate::kvm_sys::kvm_sregs).
    ///
    /// [kvm-set-sregs]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-set-sregs
    pub fn set_sregs(&self, sregs: kvm_sys::kvm_sregs) -> io::Result<()> {
        ioctl(
            &self.vcpu,
            kvm_sys::KVM_SET_SREGS,
            &sregs as *const _ as u64,
        )
        .map(|_| ())
    }

    /// Run the guest VCPU with the [`KVM_RUN`][kvm-run] ioctl until it exits with one of the exit
    /// reasons described in [`KvmExit`](crate::vcpu::KvmExit).
    ///
    /// [kvm-run]: https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-run
    pub fn run(&mut self) -> io::Result<KvmExit<'_>> {
        ioctl(&self.vcpu, kvm_sys::KVM_RUN, 0)?;

        let kvm_run = self.kvm_run.as_mut();

        match kvm_run.exit_reason as u64 {
            kvm_sys::KVM_EXIT_HLT => Ok(KvmExit::Halt),
            kvm_sys::KVM_EXIT_IO => {
                // Safe to use union `io` field, as Kernel instructed us to.
                let io = unsafe { kvm_run.inner.io };

                let kvm_run_ptr = kvm_run as *mut kvm_sys::kvm_run as *mut u8;

                // Create IO buffer located at `kvm_run + io.offset`.
                let data = unsafe {
                    std::slice::from_raw_parts_mut(
                        kvm_run_ptr.offset(io.data_offset as isize),
                        io.count /* num blocks */ as usize * io.size /* bytes per block */ as usize,
                    )
                };

                match io.direction as u64 {
                    kvm_sys::KVM_EXIT_IO_IN => Ok(KvmExit::IoIn(io.port, data)),
                    kvm_sys::KVM_EXIT_IO_OUT => Ok(KvmExit::IoOut(io.port, data)),
                    _ => unreachable!(),
                }
            }
            kvm_sys::KVM_EXIT_MMIO => {
                // Safe to use union `mmio` filed, as Kernel instructed us to.
                let mmio = unsafe { &mut kvm_run.inner.mmio };
                let len = mmio.len as usize;

                match mmio.is_write {
                    0 => Ok(KvmExit::MmioRead(mmio.phys_addr, &mut mmio.data[..len])),
                    1 => Ok(KvmExit::MmioWrite(mmio.phys_addr, &mmio.data[..len])),
                    _ => unreachable!(),
                }
            }
            r @ _ => {
                todo!("KVM_EXIT_... (exit_reason={}) not implemented!", r)
            }
        }
    }
}