hypervisor: Add KVM implementation

For each of the traits we are defining kvm related structures
and add the trait implementation to the structs. For more information
please see the kvm-ioctls and kvm-bindings crate.

This is a standalone implementation that does not include the switch of
the Cloud-Hypervisor vmm and arch crates to it.

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

hypervisor/src/kvm/x86_64/mod.rs

@@ -8,6 +8,10 @@
 //
 //
 
+use vm_memory::GuestAddress;
+
+use crate::kvm::{Cap, Kvm, KvmError, KvmResult};
+
 ///
 /// Export generically-named wrappers of kvm-bindings for Unix-based platforms
 ///
@@ -16,3 +20,21 @@ pub use {
     kvm_bindings::kvm_xcrs as ExtendedControlRegisters, kvm_bindings::kvm_xsave as Xsave,
     kvm_bindings::CpuId, kvm_bindings::Msrs as MsrEntries,
 };
+
+pub const KVM_TSS_ADDRESS: GuestAddress = GuestAddress(0xfffb_d000);
+
+///
+/// Check KVM extension for Linux
+///
+pub fn check_required_kvm_extensions(kvm: &Kvm) -> KvmResult<()> {
+    if !kvm.check_extension(Cap::SignalMsi) {
+        return Err(KvmError::CapabilityMissing(Cap::SignalMsi));
+    }
+    if !kvm.check_extension(Cap::TscDeadlineTimer) {
+        return Err(KvmError::CapabilityMissing(Cap::TscDeadlineTimer));
+    }
+    if !kvm.check_extension(Cap::SplitIrqchip) {
+        return Err(KvmError::CapabilityMissing(Cap::SplitIrqchip));
+    }
+    Ok(())
+}