hypervisor: Add Hypervisor trait

As the only hypervisor that Cloud-Hypervisor supports is KVM, the
Hypervisor trait accomodates for the upcoming KVM implementation.

This trait will be instanciated at build time through hypervisor
specific features, i.e. it's not aiming at run-time selection of
hypervisors for Cloud-Hypervisor.

Signed-off-by: Muminul Islam <muislam@microsoft.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

hypervisor/src/hypervisor.rs

@@ -0,0 +1,106 @@
+// Copyright © 2019 Intel Corporation
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Copyright © 2020, Microsoft  Corporation
+//
+// Copyright 2018-2019 CrowdStrike, Inc.
+//
+//
+use crate::vm::Vm;
+#[cfg(target_arch = "x86_64")]
+use crate::x86_64::CpuId;
+
+use kvm_ioctls::Cap;
+use std::sync::Arc;
+
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+///
+///
+pub enum HypervisorError {
+    ///
+    /// Vm creation failure
+    ///
+    #[error("Failed to create Vm: {0}")]
+    VmCreate(#[source] anyhow::Error),
+    ///
+    /// Vm setup failure
+    ///
+    #[error("Failed to setup Vm: {0}")]
+    VmSetup(#[source] anyhow::Error),
+    ///
+    /// API version error
+    ///
+    #[error("Failed to get API Version: {0}")]
+    GetApiVersion(#[source] anyhow::Error),
+    ///
+    /// Vcpu mmap error
+    ///
+    #[error("Failed to get Vcpu Mmap: {0}")]
+    GetVcpuMmap(#[source] anyhow::Error),
+    ///
+    /// Max Vcpu error
+    ///
+    #[error("Failed to get number of max vcpus: {0}")]
+    GetMaxVcpu(#[source] anyhow::Error),
+    ///
+    /// Recommended Vcpu error
+    ///
+    #[error("Failed to get number of max vcpus: {0}")]
+    GetNrVcpus(#[source] anyhow::Error),
+    ///
+    /// CpuId error
+    ///
+    #[error("Failed to get number of max vcpus: {0}")]
+    GetCpuId(#[source] anyhow::Error),
+}
+
+///
+/// Result type for returning from a function
+///
+pub type Result<T> = std::result::Result<T, HypervisorError>;
+
+///
+/// Trait to represent a Hypervisor
+///
+/// This crate provides a hypervisor-agnostic interfaces
+///
+pub trait Hypervisor: Send + Sync {
+    ///
+    /// Create a Vm using the underlying hypervisor
+    /// Return a hypervisor-agnostic Vm trait object
+    ///
+    fn create_vm(&self) -> Result<Arc<dyn Vm>>;
+    ///
+    /// Get the API version of the hypervisor
+    ///
+    fn get_api_version(&self) -> i32;
+    ///
+    /// Returns the size of the memory mapping required to use the vcpu's structures
+    ///
+    fn get_vcpu_mmap_size(&self) -> Result<usize>;
+    ///
+    /// Gets the recommended maximum number of VCPUs per VM.
+    ///
+    fn get_max_vcpus(&self) -> Result<usize>;
+    ///
+    /// Gets the recommended number of VCPUs per VM.
+    ///
+    fn get_nr_vcpus(&self) -> Result<usize>;
+    #[cfg(target_arch = "x86_64")]
+    ///
+    /// Checks if a particular `Cap` is available.
+    ///
+    fn check_capability(&self, c: Cap) -> bool;
+    #[cfg(target_arch = "x86_64")]
+    ///
+    /// Get the supported CpuID
+    ///
+    fn get_cpuid(&self) -> Result<CpuId>;
+    ///
+    /// Check particular extensions if any
+    ///
+    fn check_required_extensions(&self) -> Result<()>;
+}

hypervisor/src/lib.rs

@@ -21,11 +21,15 @@
 /// KVM implementation module
 pub mod kvm;
 
+/// Hypevisor related module
+pub mod hypervisor;
+
 /// Vm related module
 pub mod vm;
 
 /// CPU related module
 mod cpu;
 
+pub use crate::hypervisor::{Hypervisor, HypervisorError};
 pub use cpu::{HypervisorCpuError, Vcpu};
 pub use kvm::*;