KVM: VMX: Check for full VMX support when verifying CPU compatibility

Explicitly check the current CPU's IA32_FEAT_CTL and VMX feature flags
when verifying compatibility across physical CPUs.  This effectively
adds a check on IA32_FEAT_CTL to ensure that VMX is fully enabled on
all CPUs.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20191221044513.21680-17-sean.j.christopherson@intel.com

arch/x86/kvm/vmx/vmx.c

@@ -6838,6 +6838,12 @@ static int __init vmx_check_processor_compat(void)
 	struct vmcs_config vmcs_conf;
 	struct vmx_capability vmx_cap;
 
+	if (!this_cpu_has(X86_FEATURE_MSR_IA32_FEAT_CTL) ||
+	    !this_cpu_has(X86_FEATURE_VMX)) {
+		pr_err("kvm: VMX is disabled on CPU %d\n", smp_processor_id());
+		return -EIO;
+	}
+
 	if (setup_vmcs_config(&vmcs_conf, &vmx_cap) < 0)
 		return -EIO;
 	if (nested)