KVM: x86: Use cpu_feature_enabled() for PKU instead of #ifdef

Replace an #ifdef on CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS with a
cpu_feature_enabled() check on X86_FEATURE_PKU.  The macro magic of
DISABLED_MASK_BIT_SET() means that cpu_feature_enabled() provides the
same end result (no code generated) when PKU is disabled by Kconfig.

No functional change intended.

Cc: Jon Kohler <jon@nutanix.com>
Reviewed-by: Jon Kohler <jon@nutanix.com>
Link: https://lore.kernel.org/r/20230602010550.785722-1-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/x86.c

@@ -1017,13 +1017,11 @@ void kvm_load_guest_xsave_state(struct kvm_vcpu *vcpu)
 			wrmsrl(MSR_IA32_XSS, vcpu->arch.ia32_xss);
 	}
 
-#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
-	if (static_cpu_has(X86_FEATURE_PKU) &&
+	if (cpu_feature_enabled(X86_FEATURE_PKU) &&
 	    vcpu->arch.pkru != vcpu->arch.host_pkru &&
 	    ((vcpu->arch.xcr0 & XFEATURE_MASK_PKRU) ||
 	     kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE)))
 		write_pkru(vcpu->arch.pkru);
-#endif /* CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS */
 }
 EXPORT_SYMBOL_GPL(kvm_load_guest_xsave_state);
 
@@ -1032,15 +1030,13 @@ void kvm_load_host_xsave_state(struct kvm_vcpu *vcpu)
 	if (vcpu->arch.guest_state_protected)
 		return;
 
-#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
-	if (static_cpu_has(X86_FEATURE_PKU) &&
+	if (cpu_feature_enabled(X86_FEATURE_PKU) &&
 	    ((vcpu->arch.xcr0 & XFEATURE_MASK_PKRU) ||
 	     kvm_is_cr4_bit_set(vcpu, X86_CR4_PKE))) {
 		vcpu->arch.pkru = rdpkru();
 		if (vcpu->arch.pkru != vcpu->arch.host_pkru)
 			write_pkru(vcpu->arch.host_pkru);
 	}
-#endif /* CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS */
 
 	if (kvm_is_cr4_bit_set(vcpu, X86_CR4_OSXSAVE)) {