KVM: x86: Handle MPX CPUID adjustment in VMX code

Move the MPX CPUID adjustments into VMX to eliminate an instance of the
undesirable "unsigned f_* = *_supported ? F(*) : 0" pattern in the
common CPUID handling code.

Note, to maintain existing behavior, VMX must manually check for kernel
support for MPX by querying boot_cpu_has(X86_FEATURE_MPX).  Previously,
do_cpuid_7_mask() masked MPX based on boot_cpu_data by invoking
cpuid_mask() on the associated cpufeatures word, but cpuid_mask() runs
prior to executing vmx_set_supported_cpuid().

No functional change intended.
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

@@ -332,7 +332,6 @@ static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
 static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
 {
 	unsigned f_invpcid = kvm_x86_ops->invpcid_supported() ? F(INVPCID) : 0;
-	unsigned f_mpx = kvm_mpx_supported() ? F(MPX) : 0;
 	unsigned f_umip = kvm_x86_ops->umip_emulated() ? F(UMIP) : 0;
 	unsigned f_intel_pt = kvm_x86_ops->pt_supported() ? F(INTEL_PT) : 0;
 	unsigned f_la57;
@@ -341,7 +340,7 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry)
 	/* cpuid 7.0.ebx */
 	const u32 kvm_cpuid_7_0_ebx_x86_features =
 		F(FSGSBASE) | F(BMI1) | F(HLE) | F(AVX2) | F(SMEP) |
-		F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | f_mpx | F(RDSEED) |
+		F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | 0 /*MPX*/ | F(RDSEED) |
 		F(ADX) | F(SMAP) | F(AVX512IFMA) | F(AVX512F) | F(AVX512PF) |
 		F(AVX512ER) | F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB) | F(AVX512DQ) |
 		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | f_intel_pt;

arch/x86/kvm/vmx/vmx.c

@@ -7130,8 +7130,18 @@ static void vmx_cpuid_update(struct kvm_vcpu *vcpu)
 
 static void vmx_set_supported_cpuid(struct kvm_cpuid_entry2 *entry)
 {
-	if (entry->function == 1 && nested)
-		entry->ecx |= feature_bit(VMX);
+	switch (entry->function) {
+	case 0x1:
+		if (nested)
+			cpuid_entry_set(entry, X86_FEATURE_VMX);
+		break;
+	case 0x7:
+		if (boot_cpu_has(X86_FEATURE_MPX) && kvm_mpx_supported())
+			cpuid_entry_set(entry, X86_FEATURE_MPX);
+		break;
+	default:
+		break;
+	}
 }
 
 static void vmx_request_immediate_exit(struct kvm_vcpu *vcpu)