x86: Expose SERIALIZE for supported cpuid

The SERIALIZE instruction is supported by Tntel processors, like
Sapphire Rapids.  SERIALIZE is a faster serializing instruction which
does not modify registers, arithmetic flags or memory, will not cause VM
exit. It's availability is indicated by CPUID.(EAX=7,ECX=0):ECX[bit 14].

Expose it in KVM supported CPUID.  This way, KVM could pass this
information to guests and they can make use of these features accordingly.
Signed-off-by: NCathy Zhang <cathy.zhang@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

@@ -370,7 +370,8 @@ void kvm_set_cpu_caps(void)
 	kvm_cpu_cap_mask(CPUID_7_EDX,
 		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
 		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
-		F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM)
+		F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) |
+		F(SERIALIZE)
 	);
 
 	/* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */