hypervisor: Add an API to create default StandardRegisters

This will be used to create StandardRegisters for a given vcpu in
future.

Signed-off-by: Jinank Jain <jinankjain@microsoft.com>

hypervisor/src/cpu.rs

@@ -321,6 +321,12 @@ pub type Result<T> = anyhow::Result<T, HypervisorCpuError>;
 /// Trait to represent a generic Vcpu
 ///
 pub trait Vcpu: Send + Sync {
+    ///
+    /// Returns StandardRegisters with default value set
+    ///
+    fn create_standard_regs(&self) -> StandardRegisters {
+        unimplemented!();
+    }
     ///
     /// Returns the vCPU general purpose registers.
     ///

hypervisor/src/kvm/mod.rs

@@ -1190,6 +1190,13 @@ pub struct KvmVcpu {
 /// let vcpu = vm.create_vcpu(0, None).unwrap();
 /// ```
 impl cpu::Vcpu for KvmVcpu {
+    ///
+    /// Returns StandardRegisters with default value set
+    ///
+    #[cfg(target_arch = "x86_64")]
+    fn create_standard_regs(&self) -> StandardRegisters {
+        kvm_bindings::kvm_regs::default().into()
+    }
     #[cfg(target_arch = "x86_64")]
     ///
     /// Returns the vCPU general purpose registers.

hypervisor/src/mshv/mod.rs

@@ -413,6 +413,13 @@ pub struct MshvVcpu {
 /// let vcpu = vm.create_vcpu(0, None).unwrap();
 /// ```
 impl cpu::Vcpu for MshvVcpu {
+    ///
+    /// Returns StandardRegisters with default value set
+    ///
+    #[cfg(target_arch = "x86_64")]
+    fn create_standard_regs(&self) -> crate::arch::x86::StandardRegisters {
+        mshv_bindings::StandardRegisters::default().into()
+    }
     #[cfg(target_arch = "x86_64")]
     ///
     /// Returns the vCPU general purpose registers.