hypervisor/

lib.rs

// Copyright 2020 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! A crate for abstracting the underlying kernel hypervisor used in crosvm.

#[cfg(target_arch = "aarch64")]
pub mod aarch64;
pub mod caps;
#[cfg(all(unix, target_arch = "aarch64", feature = "geniezone"))]
pub mod geniezone;
#[cfg(all(unix, target_arch = "aarch64", feature = "gunyah"))]
pub mod gunyah;
#[cfg(target_arch = "aarch64")]
#[cfg(all(unix, target_arch = "aarch64", feature = "halla"))]
pub mod halla;
#[cfg(all(windows, feature = "haxm"))]
pub mod haxm;
#[cfg(any(target_os = "android", target_os = "linux"))]
pub mod kvm;
#[cfg(target_arch = "riscv64")]
pub mod riscv64;
#[cfg(all(windows, feature = "whpx"))]
pub mod whpx;
#[cfg(target_arch = "x86_64")]
pub mod x86_64;

use base::AsRawDescriptor;
use base::Event;
use base::MappedRegion;
use base::Protection;
use base::Result;
use base::SafeDescriptor;
use serde::Deserialize;
use serde::Serialize;
use vm_memory::GuestAddress;
use vm_memory::GuestMemory;

#[cfg(target_arch = "aarch64")]
pub use crate::aarch64::*;
pub use crate::caps::*;
#[cfg(target_arch = "riscv64")]
pub use crate::riscv64::*;
#[cfg(target_arch = "x86_64")]
pub use crate::x86_64::*;

/// An index in the list of guest-mapped memory regions.
pub type MemSlot = u32;

/// Range of GPA space. Starting from `guest_address` up to `size`.
pub struct MemRegion {
    pub guest_address: GuestAddress,
    pub size: u64,
}

/// Signal to the hypervisor on kernels that support the KVM_CAP_USER_CONFIGURE_NONCOHERENT_DMA (or
/// equivalent) that during user memory region (memslot) configuration, a guest page's memtype
/// should be considered in SLAT effective memtype determination rather than implicitly respecting
/// only the host page's memtype.
///
/// This explicit control is needed for Virtio devices (e.g. gpu) that configure memslots for host
/// WB page mappings with guest WC page mappings. See b/316337317, b/360295883 for more detail.
#[derive(Copy, Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
pub enum MemCacheType {
    /// Don't provide any explicit instruction to the hypervisor on how it should determine a
    /// memslot's effective memtype.
    ///
    /// On KVM-VMX (Intel), this means that the memslot is flagged with VMX_EPT_IPAT_BIT such that
    /// only the host memtype is respected.
    CacheCoherent,
    /// explicitly instruct the hypervisor to respect the guest page's memtype when determining the
    /// memslot's effective memtype.
    ///
    /// On KVM-VMX (Intel), this means the memslot is NOT flagged with VMX_EPT_IPAT_BIT, and the
    /// effective memtype will generally decay to the weaker amongst the host/guest memtypes and
    /// the MTRR for the physical address.
    CacheNonCoherent,
}

/// This is intended for use with virtio-balloon, where a guest driver determines unused ranges and
/// requests they be freed. Use without the guest's knowledge is sure to break something.
pub enum BalloonEvent {
    /// Balloon event when the region is acquired from the guest. The guest cannot access this
    /// region any more. The guest memory can be reclaimed by the host OS. As per virtio-balloon
    /// spec, the given address and size are intended to be page-aligned.
    Inflate(MemRegion),
    /// Balloon event when the region is returned to the guest. VMM should reallocate memory and
    /// register it with the hypervisor for accesses by the guest.
    Deflate(MemRegion),
    /// Balloon event when the requested memory size is achieved. This can be achieved through
    /// either inflation or deflation. The `u64` will be the current size of the balloon in bytes.
    BalloonTargetReached(u64),
}

/// Supported hypervisors.
///
/// When adding a new one, also update the HypervisorFfi in crosvm_control/src/lib.rs
#[derive(Serialize, Deserialize, Debug, Clone)]
pub enum HypervisorKind {
    Geniezone,
    Gunyah,
    Halla,
    Kvm,
    Haxm,
    Whpx,
}

/// A trait for checking hypervisor capabilities.
pub trait Hypervisor: Send {
    /// Makes a shallow clone of this `Hypervisor`.
    fn try_clone(&self) -> Result<Self>
    where
        Self: Sized;

    /// Checks if a particular `HypervisorCap` is available.
    fn check_capability(&self, cap: HypervisorCap) -> bool;
}

/// A wrapper for using a VM and getting/setting its state.
pub trait Vm: Send {
    /// Makes a shallow clone of this `Vm`.
    fn try_clone(&self) -> Result<Self>
    where
        Self: Sized;

    /// Makes a shallow clone of the fd of this `Vm`.
    fn try_clone_descriptor(&self) -> Result<SafeDescriptor>;

    /// Returns hypervisor managing this `Vm`.
    fn hypervisor_kind(&self) -> HypervisorKind;

    /// Checks if a particular `VmCap` is available.
    ///
    /// This is distinct from the `Hypervisor` version of this method because some extensions depend
    /// on the particular `Vm` instance. This method is encouraged because it more accurately
    /// reflects the usable capabilities.
    fn check_capability(&self, c: VmCap) -> bool;

    /// Enable the VM capabilities.
    fn enable_capability(&self, _capability: VmCap, _flags: u32) -> Result<bool> {
        Err(std::io::Error::from(std::io::ErrorKind::Unsupported).into())
    }

    /// Get the guest physical address size in bits.
    fn get_guest_phys_addr_bits(&self) -> u8;

    /// Gets the guest-mapped memory for the Vm.
    fn get_memory(&self) -> &GuestMemory;

    /// Inserts the given `MappedRegion` into the VM's address space at `guest_addr`.
    ///
    /// The slot that was assigned the memory mapping is returned on success.  The slot can be given
    /// to `Vm::remove_memory_region` to remove the memory from the VM's address space and take back
    /// ownership of `mem_region`.
    ///
    /// Note that memory inserted into the VM's address space must not overlap with any other memory
    /// slot's region.
    ///
    /// If `read_only` is true, the guest will be able to read the memory as normal, but attempts to
    /// write will trigger a mmio VM exit, leaving the memory untouched.
    ///
    /// If `log_dirty_pages` is true, the slot number can be used to retrieve the pages written to
    /// by the guest with `get_dirty_log`.
    ///
    /// `cache` can be used to set guest mem cache attribute if supported. Default is cache coherent
    /// memory. Noncoherent memory means this memory might not be coherent from all access points,
    /// e.g this could be the case when host GPU doesn't set the memory to be coherent with CPU
    /// access. Setting this attribute would allow hypervisor to adjust guest mem control to ensure
    /// synchronized guest access in noncoherent DMA case.
    fn add_memory_region(
        &mut self,
        guest_addr: GuestAddress,
        mem_region: Box<dyn MappedRegion>,
        read_only: bool,
        log_dirty_pages: bool,
        cache: MemCacheType,
    ) -> Result<MemSlot>;

    /// Does a synchronous msync of the memory mapped at `slot`, syncing `size` bytes starting at
    /// `offset` from the start of the region.  `offset` must be page aligned.
    fn msync_memory_region(&mut self, slot: MemSlot, offset: usize, size: usize) -> Result<()>;

    /// Gives a MADV_PAGEOUT advice to the memory region mapped at `slot`, with the address range
    /// starting at `offset` from the start of the region, and with size `size`. `offset`
    /// must be page aligned.
    #[cfg(any(target_os = "android", target_os = "linux"))]
    fn madvise_pageout_memory_region(
        &mut self,
        slot: MemSlot,
        offset: usize,
        size: usize,
    ) -> Result<()>;

    /// Gives a MADV_REMOVE advice to the memory region mapped at `slot`, with the address range
    /// starting at `offset` from the start of the region, and with size `size`. `offset`
    /// must be page aligned.
    #[cfg(any(target_os = "android", target_os = "linux"))]
    fn madvise_remove_memory_region(
        &mut self,
        slot: MemSlot,
        offset: usize,
        size: usize,
    ) -> Result<()>;

    /// Removes and drops the `UserMemoryRegion` that was previously added at the given slot.
    fn remove_memory_region(&mut self, slot: MemSlot) -> Result<Box<dyn MappedRegion>>;

    /// Creates an emulated device.
    fn create_device(&self, kind: DeviceKind) -> Result<SafeDescriptor>;

    /// Gets the bitmap of dirty pages since the last call to `get_dirty_log` for the memory at
    /// `slot`.  Only works on VMs that support `VmCap::DirtyLog`.
    ///
    /// The size of `dirty_log` must be at least as many bits as there are pages in the memory
    /// region `slot` represents. For example, if the size of `slot` is 16 pages, `dirty_log` must
    /// be 2 bytes or greater.
    fn get_dirty_log(&self, slot: MemSlot, dirty_log: &mut [u8]) -> Result<()>;

    /// Registers an event to be signaled whenever a certain address is written to.
    ///
    /// The `datamatch` parameter can be used to limit signaling `evt` to only the cases where the
    /// value being written is equal to `datamatch`. Note that the size of `datamatch` is important
    /// and must match the expected size of the guest's write.
    ///
    /// In all cases where `evt` is signaled, the ordinary vmexit to userspace that would be
    /// triggered is prevented.
    fn register_ioevent(
        &mut self,
        evt: &Event,
        addr: IoEventAddress,
        datamatch: Datamatch,
    ) -> Result<()>;

    /// Unregisters an event previously registered with `register_ioevent`.
    ///
    /// The `evt`, `addr`, and `datamatch` set must be the same as the ones passed into
    /// `register_ioevent`.
    fn unregister_ioevent(
        &mut self,
        evt: &Event,
        addr: IoEventAddress,
        datamatch: Datamatch,
    ) -> Result<()>;

    /// Trigger any matching registered io events based on an MMIO or PIO write at `addr`. The
    /// `data` slice represents the contents and length of the write, which is used to compare with
    /// the registered io events' Datamatch values. If the hypervisor does in-kernel IO event
    /// delivery, this is a no-op.
    fn handle_io_events(&self, addr: IoEventAddress, data: &[u8]) -> Result<()>;

    /// Retrieves the current timestamp of the paravirtual clock as seen by the current guest.
    /// Only works on VMs that support `VmCap::PvClock`.
    fn get_pvclock(&self) -> Result<ClockState>;

    /// Sets the current timestamp of the paravirtual clock as seen by the current guest.
    /// Only works on VMs that support `VmCap::PvClock`.
    fn set_pvclock(&self, state: &ClockState) -> Result<()>;

    /// Maps `size` bytes starting at `fs_offset` bytes from within the given `fd`
    /// at `offset` bytes from the start of the arena with `prot` protections.
    /// `offset` must be page aligned.
    ///
    /// # Arguments
    /// * `offset` - Page aligned offset into the arena in bytes.
    /// * `size` - Size of memory region in bytes.
    /// * `fd` - File descriptor to mmap from.
    /// * `fd_offset` - Offset in bytes from the beginning of `fd` to start the mmap.
    /// * `prot` - Protection (e.g. readable/writable) of the memory region.
    fn add_fd_mapping(
        &mut self,
        slot: u32,
        offset: usize,
        size: usize,
        fd: &dyn AsRawDescriptor,
        fd_offset: u64,
        prot: Protection,
    ) -> Result<()>;

    /// Remove `size`-byte mapping starting at `offset`.
    fn remove_mapping(&mut self, slot: u32, offset: usize, size: usize) -> Result<()>;

    /// Events from virtio-balloon that affect the state for guest memory and host memory.
    fn handle_balloon_event(&mut self, event: BalloonEvent) -> Result<()>;

    /// Registers with the hypervisor for CrosVM to handle any guest hypercall in the range.
    fn enable_hypercalls(&mut self, nr: u64, count: usize) -> Result<()>;

    /// Registers with the hypervisor for CrosVM to handle the guest hypercall.
    fn enable_hypercall(&mut self, nr: u64) -> Result<()> {
        self.enable_hypercalls(nr, 1)
    }
}

/// Operation for Io and Mmio
#[derive(Debug)]
pub enum IoOperation<'a> {
    /// Data to be read from a device on the bus.
    ///
    /// The `handle_fn` should fill the entire slice with the read data.
    Read(&'a mut [u8]),

    /// Data to be written to a device on the bus.
    Write(&'a [u8]),
}

/// Parameters describing an MMIO or PIO from the guest.
#[derive(Debug)]
pub struct IoParams<'a> {
    pub address: u64,
    pub operation: IoOperation<'a>,
}

/// Architecture-agnostic wrapper for any hypercall ABI between CrosVM and the guest.
#[derive(Debug)]
pub struct HypercallAbi {
    hypercall_id: usize,
    args: Vec<usize>,
    res: Vec<usize>,
}

impl HypercallAbi {
    /// Creates a new `HypercallAbi` instance, with the default error result.
    pub fn new(hypercall_id: usize, args: &[usize], default_res: &[usize]) -> Self {
        Self {
            hypercall_id,
            args: args.to_owned(),
            res: default_res.to_owned(),
        }
    }

    /// Returns the hypercall unique identifier, for routing.
    pub fn hypercall_id(&self) -> usize {
        self.hypercall_id
    }

    /// Returns the n-th guest-provided architecture-specific arguments.
    pub fn get_argument(&self, n: usize) -> Option<&usize> {
        self.args.get(n)
    }

    /// Returns the architecture-specific results for the guest, if set.
    pub fn get_results(&self) -> &[usize] {
        self.res.as_slice()
    }

    /// Sets the architecture-specific results for the guest.
    pub fn set_results(&mut self, res: &[usize]) {
        self.res = res.to_owned()
    }
}

/// Handle to a virtual CPU that may be used to request a VM exit from within a signal handler.
#[cfg(any(target_os = "android", target_os = "linux"))]
pub struct VcpuSignalHandle {
    inner: Box<dyn VcpuSignalHandleInner>,
}

#[cfg(any(target_os = "android", target_os = "linux"))]
impl VcpuSignalHandle {
    /// Request an immediate exit for this VCPU.
    ///
    /// This function is safe to call from a signal handler.
    pub fn signal_immediate_exit(&self) {
        self.inner.signal_immediate_exit()
    }
}

/// Signal-safe mechanism for requesting an immediate VCPU exit.
///
/// Each hypervisor backend must implement this for its VCPU type.
#[cfg(any(target_os = "android", target_os = "linux"))]
pub(crate) trait VcpuSignalHandleInner {
    /// Signal the associated VCPU to exit if it is currently running.
    ///
    /// # Safety
    ///
    /// The implementation of this function must be async signal safe.
    /// <https://man7.org/linux/man-pages/man7/signal-safety.7.html>
    fn signal_immediate_exit(&self);
}

/// A virtual CPU holding a virtualized hardware thread's state, such as registers and interrupt
/// state, which may be used to execute virtual machines.
pub trait Vcpu: downcast_rs::DowncastSync {
    /// Makes a shallow clone of this `Vcpu`.
    fn try_clone(&self) -> Result<Self>
    where
        Self: Sized;

    /// Casts this architecture specific trait object to the base trait object `Vcpu`.
    fn as_vcpu(&self) -> &dyn Vcpu;

    /// Runs the VCPU until it exits, returning the reason for the exit.
    fn run(&mut self) -> Result<VcpuExit>;

    /// Returns the vcpu id.
    fn id(&self) -> usize;

    /// Sets the bit that requests an immediate exit.
    fn set_immediate_exit(&self, exit: bool);

    /// Returns a handle that can be used to cause this VCPU to exit from `run()` from a signal
    /// handler.
    #[cfg(any(target_os = "android", target_os = "linux"))]
    fn signal_handle(&self) -> VcpuSignalHandle;

    /// Handles an incoming MMIO request from the guest.
    ///
    /// This function should be called after `Vcpu::run` returns `VcpuExit::Mmio`, and in the same
    /// thread as run().
    ///
    /// Once called, it will determine whether a MMIO read or MMIO write was the reason for the MMIO
    /// exit, call `handle_fn` with the respective IoParams to perform the MMIO read or write, and
    /// set the return data in the vcpu so that the vcpu can resume running.
    fn handle_mmio(&self, handle_fn: &mut dyn FnMut(IoParams) -> Result<()>) -> Result<()>;

    /// Handles an incoming PIO from the guest.
    ///
    /// This function should be called after `Vcpu::run` returns `VcpuExit::Io`, and in the same
    /// thread as run().
    ///
    /// Once called, it will determine whether an input or output was the reason for the Io exit,
    /// call `handle_fn` with the respective IoParams to perform the input/output operation, and set
    /// the return data in the vcpu so that the vcpu can resume running.
    fn handle_io(&self, handle_fn: &mut dyn FnMut(IoParams)) -> Result<()>;

    /// Handles an incoming hypercall from the guest.
    fn handle_hypercall(
        &self,
        _handle_fn: &mut dyn FnMut(&mut HypercallAbi) -> anyhow::Result<()>,
    ) -> anyhow::Result<()> {
        anyhow::bail!(
            "handle_hypercall not implemented for {}",
            std::any::type_name::<Self>(),
        )
    }

    /// Signals to the hypervisor that this Vcpu is being paused by userspace.
    fn on_suspend(&self) -> Result<()>;

    /// Enables a hypervisor-specific extension on this Vcpu.  `cap` is a constant defined by the
    /// hypervisor API (e.g., kvm.h).  `args` are the arguments for enabling the feature, if any.
    ///
    /// # Safety
    /// This function is marked as unsafe because `args` may be interpreted as pointers for some
    /// capabilities. The caller must ensure that any pointers passed in the `args` array are
    /// allocated as the kernel expects, and that mutable pointers are owned.
    unsafe fn enable_raw_capability(&self, cap: u32, args: &[u64; 4]) -> Result<()>;
}

downcast_rs::impl_downcast!(sync Vcpu);

/// An address either in programmable I/O space or in memory mapped I/O space.
#[derive(Copy, Clone, Debug, Serialize, Deserialize, PartialEq, Eq, std::hash::Hash)]
pub enum IoEventAddress {
    Pio(u64),
    Mmio(u64),
}

/// Used in `Vm::register_ioevent` to indicate a size and optionally value to match.
#[derive(Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub enum Datamatch {
    AnyLength,
    U8(Option<u8>),
    U16(Option<u16>),
    U32(Option<u32>),
    U64(Option<u64>),
}

#[derive(Copy, Clone, Debug)]
pub enum VcpuShutdownErrorKind {
    DoubleFault,
    TripleFault,
    Other,
}

/// A Vcpu shutdown may signify an error, such as a double or triple fault,
/// or hypervisor specific reasons. This error covers all such cases.
#[derive(Copy, Clone, Debug)]
pub struct VcpuShutdownError {
    kind: VcpuShutdownErrorKind,
    raw_error_code: u64,
}

impl VcpuShutdownError {
    pub fn new(kind: VcpuShutdownErrorKind, raw_error_code: u64) -> VcpuShutdownError {
        Self {
            kind,
            raw_error_code,
        }
    }
    pub fn kind(&self) -> VcpuShutdownErrorKind {
        self.kind
    }
    pub fn get_raw_error_code(&self) -> u64 {
        self.raw_error_code
    }
}

// Note that when adding entries to the VcpuExit enum you may want to add corresponding entries in
// crosvm::stats::exit_to_index and crosvm::stats::exit_index_to_str if you don't want the new
// exit type to be categorized as "Unknown".

/// A reason why a VCPU exited. One of these returns every time `Vcpu::run` is called.
#[derive(Debug, Clone, Copy)]
pub enum VcpuExit {
    /// An io instruction needs to be emulated.
    /// vcpu handle_io should be called to handle the io operation
    Io,
    /// A mmio instruction needs to be emulated.
    /// vcpu handle_mmio should be called to handle the mmio operation
    Mmio,
    IoapicEoi {
        vector: u8,
    },
    Exception,
    Hypercall,
    Debug,
    Hlt,
    IrqWindowOpen,
    Shutdown(std::result::Result<(), VcpuShutdownError>),
    FailEntry {
        hardware_entry_failure_reason: u64,
    },
    Intr,
    SetTpr,
    TprAccess,
    InternalError,
    SystemEventShutdown,
    SystemEventReset,
    SystemEventCrash,
    /// An invalid vcpu register was set while running.
    InvalidVpRegister,
    /// incorrect setup for vcpu requiring an unsupported feature
    UnsupportedFeature,
    /// vcpu run was user cancelled
    Canceled,
    /// an unrecoverable exception was encountered (different from Exception)
    UnrecoverableException,
    /// vcpu stopped due to an msr access.
    MsrAccess,
    /// vcpu stopped due to a cpuid request.
    #[cfg(target_arch = "x86_64")]
    Cpuid {
        entry: CpuIdEntry,
    },
    /// vcpu stopped due to calling rdtsc
    RdTsc,
    /// vcpu stopped for an apic smi trap
    ApicSmiTrap,
    /// vcpu stopped due to an apic trap
    ApicInitSipiTrap,
    /// vcpu stoppted due to bus lock
    BusLock,
    /// Riscv supervisor call.
    Sbi {
        extension_id: u64,
        function_id: u64,
        args: [u64; 6],
    },
    /// Emulate CSR access from guest.
    RiscvCsr {
        csr_num: u64,
        new_value: u64,
        write_mask: u64,
        ret_value: u64,
    },
}

/// A device type to create with `Vm.create_device`.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum DeviceKind {
    /// VFIO device for direct access to devices from userspace
    Vfio,
    /// ARM virtual general interrupt controller v2
    #[cfg(target_arch = "aarch64")]
    ArmVgicV2,
    /// ARM virtual general interrupt controller v3
    #[cfg(target_arch = "aarch64")]
    ArmVgicV3,
    /// ARM virtual interrupt translation service
    #[cfg(target_arch = "aarch64")]
    ArmVgicIts,
    /// RiscV AIA in-kernel emulation
    #[cfg(target_arch = "riscv64")]
    RiscvAia,
}

/// The source chip of an `IrqSource`
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum IrqSourceChip {
    PicPrimary,
    PicSecondary,
    Ioapic,
    Gic,
    Aia,
}

/// A source of IRQs in an `IrqRoute`.
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum IrqSource {
    Irqchip {
        chip: IrqSourceChip,
        pin: u32,
    },
    Msi {
        address: u64,
        data: u32,
        #[cfg(target_arch = "aarch64")]
        pci_address: resources::PciAddress,
    },
}

/// A single route for an IRQ.
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct IrqRoute {
    pub gsi: u32,
    pub source: IrqSource,
}

/// The state of the paravirtual clock.
#[derive(Debug, Default, Copy, Clone, Serialize, Deserialize)]
pub struct ClockState {
    /// Current pv clock timestamp, as seen by the guest
    pub clock: u64,
}

/// The MPState represents the state of a processor.
#[repr(C)]
#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub enum MPState {
    /// the vcpu is currently running (x86/x86_64,arm/arm64)
    Runnable,
    /// the vcpu is an application processor (AP) which has not yet received an INIT signal
    /// (x86/x86_64)
    Uninitialized,
    /// the vcpu has received an INIT signal, and is now ready for a SIPI (x86/x86_64)
    InitReceived,
    /// the vcpu has executed a HLT instruction and is waiting for an interrupt (x86/x86_64)
    Halted,
    /// the vcpu has just received a SIPI (vector accessible via KVM_GET_VCPU_EVENTS) (x86/x86_64)
    SipiReceived,
    /// the vcpu is stopped (arm/arm64)
    Stopped,
}

/// Whether the VM should be run in protected mode or not.
#[derive(Copy, Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
pub enum ProtectionType {
    /// The VM should be run in the unprotected mode, where the host has access to its memory.
    Unprotected,
    /// The VM should be run in protected mode, so the host cannot access its memory directly. It
    /// should be booted via the protected VM firmware, so that it can access its secrets.
    Protected,
    /// The VM should be run in protected mode, so the host cannot access its memory directly. It
    /// should be booted via a custom VM firmware, useful for debugging and testing.
    ProtectedWithCustomFirmware,
    /// The VM should be run in protected mode, but booted directly without pVM firmware. The host
    /// will still be unable to access the VM memory, but it won't be given any secrets.
    ProtectedWithoutFirmware,
    /// The VM should be run in unprotected mode, but with the same memory layout as protected
    /// mode, protected VM firmware loaded, and simulating protected mode as much as possible.
    /// This is useful for debugging the protected VM firmware and other protected mode issues.
    UnprotectedWithFirmware,
}

impl ProtectionType {
    /// Returns whether the hypervisor will prevent us from accessing the VM's memory.
    pub fn isolates_memory(&self) -> bool {
        matches!(
            self,
            Self::Protected | Self::ProtectedWithCustomFirmware | Self::ProtectedWithoutFirmware
        )
    }

    /// Returns whether the VMM needs to load the pVM firmware.
    pub fn needs_firmware_loaded(&self) -> bool {
        matches!(
            self,
            Self::UnprotectedWithFirmware | Self::ProtectedWithCustomFirmware
        )
    }

    /// Returns whether the VM runs a pVM firmware.
    pub fn runs_firmware(&self) -> bool {
        self.needs_firmware_loaded() || matches!(self, Self::Protected)
    }
}

#[derive(Clone, Copy)]
pub struct Config {
    #[cfg(target_arch = "aarch64")]
    /// enable the Memory Tagging Extension in the guest
    pub mte: bool,
    pub protection_type: ProtectionType,
    #[cfg(all(target_os = "android", target_arch = "aarch64"))]
    pub ffa: bool,
    pub force_disable_readonly_mem: bool,
}

impl Default for Config {
    fn default() -> Config {
        Config {
            #[cfg(target_arch = "aarch64")]
            mte: false,
            protection_type: ProtectionType::Unprotected,
            #[cfg(all(target_os = "android", target_arch = "aarch64"))]
            ffa: false,
            force_disable_readonly_mem: false,
        }
    }
}