SMX should be disabled on guests.
Actually current code assumes SMX is disabled (no VM exit handler for GETSEC
and bit 2 of IA32_FEATURE_CONTROL is set), and this patch simply explicitly
clear guest CPUID.01H.ECX[6].
Since both CPUID.01H.ECX[5] and CPUID.01H.ECX[6] are cleared from guest CPUID,
MSR IA32_SMM_MONITOR_CTL is not available in guests.
Need to make sure CR4.SMXE is cleared in guests.
Tracked-On: #1867
Signed-off-by: Zide Chen <zide.chen@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
f4cce46605