This helps to improve performance:
- Don't need to execute VMREAD in vcpu_get_efer(), which is frequently
called.
- VMX_EXIT_CTLS_SAVE_EFER can be removed from VM-Exit Controls.
- If the value of IA32_EFER MSR is identical between the host and guest
(highly likely), adjust the VMX controls not to load IA32_EFER on
VMExit and VMEntry.
It's convenient to continue use the exiting vcpu_s/get_efer() APIs,
other than the common vcpu_s/get_guest_msr().
Tracked-On: #6289
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>