KVM: VMX: Don't allow uninhibited access to EFER on i386

(cherry picked from commit 16175a796d061833aacfbd9672235f2d2725df65)

vmx_set_msr() does not allow i386 guests to touch EFER, but they can still
do so through the default: label in the switch.  If they set EFER_LME, they
can oops the host.

Fix by having EFER access through the normal channel (which will check for
EFER_LME) even on i386.

Reported-and-tested-by: Benjamin Gilbert <bgilbert@cs.cmu.edu>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c960d3b..9716706 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -898,11 +898,11 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
        int ret = 0;
 
        switch (msr_index) {
-#ifdef CONFIG_X86_64
        case MSR_EFER:
                vmx_load_host_state(vmx);
                ret = kvm_set_msr_common(vcpu, msr_index, data);
                break;
+#ifdef CONFIG_X86_64
        case MSR_FS_BASE:
                vmcs_writel(GUEST_FS_BASE, data);
                break;