KVM: x86: Add a helper to check kernel support when setting cpu cap

Add a helper, kvm_cpu_cap_check_and_set(), to query boot_cpu_has() as
part of setting a KVM cpu capability.  VMX in particular has a number of
features that are dependent on both a VMCS capability and kernel
support.

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.h

@@ -282,4 +282,10 @@ static __always_inline void kvm_cpu_cap_set(unsigned int x86_feature)
 	kvm_cpu_caps[x86_leaf] |= __feature_bit(x86_feature);
 }
 
+static __always_inline void kvm_cpu_cap_check_and_set(unsigned int x86_feature)
+{
+	if (boot_cpu_has(x86_feature))
+		kvm_cpu_cap_set(x86_feature);
+}
+
 #endif

arch/x86/kvm/svm.c

@@ -1377,8 +1377,7 @@ static __init void svm_set_cpu_caps(void)
 
 	/* CPUID 0x8000000A */
 	/* Support next_rip if host supports it */
-	if (boot_cpu_has(X86_FEATURE_NRIPS))
-		kvm_cpu_cap_set(X86_FEATURE_NRIPS);
+	kvm_cpu_cap_check_and_set(X86_FEATURE_NRIPS);
 
 	if (npt_enabled)
 		kvm_cpu_cap_set(X86_FEATURE_NPT);

arch/x86/kvm/vmx/vmx.c

@@ -7149,18 +7149,16 @@ static __init void vmx_set_cpu_caps(void)
 		kvm_cpu_cap_set(X86_FEATURE_VMX);
 
 	/* CPUID 0x7 */
-	if (boot_cpu_has(X86_FEATURE_MPX) && kvm_mpx_supported())
-		kvm_cpu_cap_set(X86_FEATURE_MPX);
-	if (boot_cpu_has(X86_FEATURE_INVPCID) && cpu_has_vmx_invpcid())
-		kvm_cpu_cap_set(X86_FEATURE_INVPCID);
-	if (boot_cpu_has(X86_FEATURE_INTEL_PT) &&
-	    vmx_pt_mode_is_host_guest())
-		kvm_cpu_cap_set(X86_FEATURE_INTEL_PT);
+	if (kvm_mpx_supported())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_MPX);
+	if (cpu_has_vmx_invpcid())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_INVPCID);
+	if (vmx_pt_mode_is_host_guest())
+		kvm_cpu_cap_check_and_set(X86_FEATURE_INTEL_PT);
 
 	/* PKU is not yet implemented for shadow paging. */
-	if (enable_ept && boot_cpu_has(X86_FEATURE_PKU) &&
-	    boot_cpu_has(X86_FEATURE_OSPKE))
-		kvm_cpu_cap_set(X86_FEATURE_PKU);
+	if (enable_ept && boot_cpu_has(X86_FEATURE_OSPKE))
+		kvm_cpu_cap_check_and_set(X86_FEATURE_PKU);
 
 	/* CPUID 0xD.1 */
 	if (!vmx_xsaves_supported())