2 files changed, 10 insertions, 2 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6b01552bd1f1..ec9265b354b0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -41,7 +41,7 @@
                           | X86_CR4_OSXMMEXCPT | X86_CR4_VMXE))
 
 #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR)
-#define EFER_RESERVED_BITS 0xfffffffffffff2fe
+static u64 __read_mostly efer_reserved_bits = 0xfffffffffffff2fe;
 
 #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
@@ -428,7 +428,7 @@ static u32 emulated_msrs[] = {
 
 static void set_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
-        if (efer & EFER_RESERVED_BITS) {
+        if (efer & efer_reserved_bits) {
                 printk(KERN_DEBUG "set_efer: 0x%llx #GP, reserved bits\n",
                        efer);
                 kvm_inject_gp(vcpu, 0);
@@ -452,6 +452,13 @@ static void set_efer(struct kvm_vcpu *vcpu, u64 efer)
 
 #endif
 
+void kvm_enable_efer_bits(u64 mask)
+{
+       efer_reserved_bits &= ~mask;
+}
+EXPORT_SYMBOL_GPL(kvm_enable_efer_bits);
+
+
 /*
  * Writes msr value into into the appropriate "register".
  * Returns 0 on success, non-0 otherwise.
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 28e8177ea4a0..274f153c8704 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -430,6 +430,7 @@ void realmode_lmsw(struct kvm_vcpu *vcpu, unsigned long msw,
 unsigned long realmode_get_cr(struct kvm_vcpu *vcpu, int cr);
 void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long value,
                      unsigned long *rflags);
+void kvm_enable_efer_bits(u64);
 int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
 int kvm_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);