x86_64 support for saving and restoring kvm vcpu state

Coverage slightly decreased because kvm api errors cannot be covered.

Signed-off-by: Adrian Catangiu <[email protected]>

Author: acatangiu

src/arch/src/x86_64/msr.rs

@@ -5,12 +5,14 @@
 use std::result;
 
 use arch_gen::x86::msr_index::*;
-use kvm_bindings::{kvm_msr_entry, Msrs};
-use kvm_ioctls::VcpuFd;
+use kvm_bindings::{kvm_msr_entry, MsrList, Msrs};
+use kvm_ioctls::{Kvm, VcpuFd};
 
 #[derive(Debug)]
 /// MSR related errors.
 pub enum Error {
+    /// Getting supported MSRs failed.
+    GetSupportedModelSpecificRegisters(kvm_ioctls::Error),
     /// Setting up MSRs failed.
     SetModelSpecificRegisters(kvm_ioctls::Error),
     /// Failed to set all MSRs.
@@ -227,6 +229,21 @@ pub fn setup_msrs(vcpu: &VcpuFd) -> Result<()> {
         })
 }
 
+/// Returns the list of supported, serializable MSRs.
+///
+/// # Arguments
+///
+/// * `kvm_fd` - Structure that holds the KVM's fd.
+pub fn supported_guest_msrs(kvm_fd: &Kvm) -> Result<MsrList> {
+    let mut msr_list = kvm_fd
+        .get_msr_index_list()
+        .map_err(Error::GetSupportedModelSpecificRegisters)?;
+
+    msr_list.retain(|msr_index| msr_should_serialize(*msr_index));
+
+    Ok(msr_list)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/vmm/src/error.rs

@@ -816,9 +816,9 @@ mod tests {
             ErrorKind::Internal
         );
         assert_eq!(
-            error_kind(StartMicrovmError::VcpuConfigure(
-                vstate::Error::SetSupportedCpusFailed(utils::errno::Error::new(0))
-            )),
+            error_kind(StartMicrovmError::VcpuConfigure(vstate::Error::VcpuFd(
+                utils::errno::Error::new(0)
+            ))),
             ErrorKind::Internal
         );
         assert_eq!(

src/vmm/src/lib.rs

@@ -885,6 +885,7 @@ impl Vmm {
                     cpu_index,
                     self.vm.fd(),
                     self.vm.supported_cpuid().clone(),
+                    self.vm.supported_msrs().clone(),
                     self.pio_device_manager.io_bus.clone(),
                     vcpu_exit_evt,
                     request_ts.clone(),