KVM: X86: Go on updating other CPUID leaves when leaf 1 is absent

As handling of bits out of leaf 1 added over time, kvm_update_cpuid()
should not return directly if leaf 1 is absent, but should go on
updateing other CPUID leaves.

Keep the update of apic->lapic_timer.timer_mode_mask in a separate
wrapper, to minimize churn for code since it will be moved out of this
function in a future patch.
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-Id: <20200708065054.19713-3-xiaoyao.li@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

@@ -60,18 +60,17 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
 	struct kvm_lapic *apic = vcpu->arch.apic;
 
 	best = kvm_find_cpuid_entry(vcpu, 1, 0);
-	if (!best)
-		return 0;
-
-	/* Update OSXSAVE bit */
-	if (boot_cpu_has(X86_FEATURE_XSAVE) && best->function == 0x1)
-		cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
+	if (best) {
+		/* Update OSXSAVE bit */
+		if (boot_cpu_has(X86_FEATURE_XSAVE))
+			cpuid_entry_change(best, X86_FEATURE_OSXSAVE,
 				   kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE));
 
-	cpuid_entry_change(best, X86_FEATURE_APIC,
+		cpuid_entry_change(best, X86_FEATURE_APIC,
 			   vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE);
+	}
 
-	if (apic) {
+	if (best && apic) {
 		if (cpuid_entry_has(best, X86_FEATURE_TSC_DEADLINE_TIMER))
 			apic->lapic_timer.timer_mode_mask = 3 << 17;
 		else