KVM: align valid EFER bits with the features of the host system

This patch aligns the bits the guest can set in the EFER register with the
features in the host processor. Currently it lets EFER.NX disabled if the
processor does not support it and enables EFER.LME and EFER.LMA only for KVM on
64 bit hosts.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/x86/kvm/svm.c

@@ -403,6 +403,9 @@ static __init int svm_hardware_setup(void)
 	set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_ESP, 1, 1);
 	set_msr_interception(msrpm_va, MSR_IA32_SYSENTER_EIP, 1, 1);
 
+	if (boot_cpu_has(X86_FEATURE_NX))
+		kvm_enable_efer_bits(EFER_NX);
+
 	for_each_online_cpu(cpu) {
 		r = svm_cpu_init(cpu);
 		if (r)

arch/x86/kvm/vmx.c

@@ -1117,6 +1117,10 @@ static __init int hardware_setup(void)
 {
 	if (setup_vmcs_config(&vmcs_config) < 0)
 		return -EIO;
+
+	if (boot_cpu_has(X86_FEATURE_NX))
+		kvm_enable_efer_bits(EFER_NX);
+
 	return alloc_kvm_area();
 }
 

arch/x86/kvm/x86.c

@@ -41,7 +41,15 @@
 			  | X86_CR4_OSXMMEXCPT | X86_CR4_VMXE))
 
 #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
-static u64 __read_mostly efer_reserved_bits = 0xfffffffffffff2fe;
+/* EFER defaults:
+ * - enable syscall per default because its emulated by KVM
+ * - enable LME and LMA per default on 64 bit KVM
+ */
+#ifdef CONFIG_X86_64
+static u64 __read_mostly efer_reserved_bits = 0xfffffffffffffafeULL;
+#else
+static u64 __read_mostly efer_reserved_bits = 0xfffffffffffffffeULL;
+#endif
 
 #define VM_STAT(x) offsetof(struct kvm, stat.x), KVM_STAT_VM
 #define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU