KVM: VMX: fix incorrect cached cpl value with real/v8086 modes

Marcelo Tosatti
2012-12-19T13:29:34Z

CPL is always 0 when in real mode, and always 3 when virtual 8086 mode.

Using values other than those can cause failures on operations that check CPL.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a4ecf7c..3abe433 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3215,13 +3215,6 @@ static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)

static int __vmx_get_cpl(struct kvm_vcpu *vcpu)
{
- if (!is_protmode(vcpu))
- return 0;
-
- if (!is_long_mode(vcpu)
- && (kvm_get_rflags(vcpu) & X86_EFLAGS_VM)) /* if virtual 8086 */
- return 3;
-
return vmx_read_guest_seg_selector(to_vmx(vcpu), VCPU_SREG_CS) & 3;
}

@@ -3229,6 +3222,13 @@ static int vmx_get_cpl(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);

+ if (!is_protmode(vcpu))
+ return 0;
+
+ if (!is_long_mode(vcpu)
+ && (kvm_get_rflags(vcpu) & X86_EFLAGS_VM)) /* if virtual 8086 */
+ return 3;
+
/*
* If we enter real mode with cs.sel & 3 != 0, the normal CPL calculations
* fail; use the cache instead.