KVM: x86: add pcommit support

Pass PCOMMIT CPU feature to guest to enable PCOMMIT instruction

Currently we do not catch pcommit instruction for L1 guest and
allow L1 to catch this instruction for L2 if, as required by the spec,
L1 can enumerate the PCOMMIT instruction via CPUID:
| IA32_VMX_PROCBASED_CTLS2[53] (which enumerates support for the
| 1-setting of PCOMMIT exiting) is always the same as
| CPUID.07H:EBX.PCOMMIT[bit 22]. Thus, software can set PCOMMIT exiting
| to 1 if and only if the PCOMMIT instruction is enumerated via CPUID

The spec can be found at
https://software.intel.com/sites/default/files/managed/0d/53/319433-022.pdf

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 962fc7d..faeb0b3 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -348,7 +348,7 @@
 		F(FSGSBASE) | F(BMI1) | F(HLE) | F(AVX2) | F(SMEP) |
 		F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | f_mpx | F(RDSEED) |
 		F(ADX) | F(SMAP) | F(AVX512F) | F(AVX512PF) | F(AVX512ER) |
-		F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB);
+		F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB) | F(PCOMMIT);
 
 	/* cpuid 0xD.1.eax */
 	const u32 kvm_supported_word10_x86_features =