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>

3 files changed, 16 insertions, 1 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1a582f1090e8..ff3bc74af728 100644
--- a/arch/x86/kvm/svm.c
+++ b/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)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1157e8a4059b..a509910f6b53 100644
--- a/arch/x86/kvm/vmx.c
+++ b/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();
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ec9265b354b0..db16f2353e4b 100644
--- a/arch/x86/kvm/x86.c
+++ b/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