vmm: Ensure PIO/MMIO exits complete before pausing only for KVM

MSHV does not require to ensure MMIO/PIO exits complete
before pausing. This patch makes sure the above requirement
by checking the hypervisor type run-time.

Fixes #5037

Signed-off-by: Muminul Islam <muislam@microsoft.com>
(cherry picked from commit 4e3bc20f2c)

hypervisor/src/lib.rs

@@ -61,7 +61,7 @@ pub use vm::{
     Vm, VmOps,
 };
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub enum HypervisorType {
     Kvm,
     Mshv,