To hide CET feature from guest VM completely, the MSR IA32_MSR_XSS also
need to be intercepted because it comprises CET_U and CET_S feature bits
of xsave/xstors operations. Mask these two bits in IA32_MSR_XSS writing.
With IA32_MSR_XSS interception, member 'xss' of 'struct ext_context' can
be removed because it is duplicated with the MSR store array
'vcpu->arch.guest_msrs[]'.
Tracked-On: #5074
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>