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

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.

Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 4 insertions, 11 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 55dfc375f1ab..dd2a85c1c6f0 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1696,7 +1696,6 @@ static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu)
 static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags)
 {
         __set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail);
-        __clear_bit(VCPU_EXREG_CPL, (ulong *)&vcpu->arch.regs_avail);
         to_vmx(vcpu)->rflags = rflags;
         if (to_vmx(vcpu)->rmode.vm86_active) {
                 to_vmx(vcpu)->rmode.save_rflags = rflags;
@@ -3110,7 +3109,6 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
         vmcs_writel(CR0_READ_SHADOW, cr0);
         vmcs_writel(GUEST_CR0, hw_cr0);
         vcpu->arch.cr0 = cr0;
-        __clear_bit(VCPU_EXREG_CPL, (ulong *)&vcpu->arch.regs_avail);
 }
 
 static u64 construct_eptp(unsigned long root_hpa)
@@ -3220,8 +3218,10 @@ static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)
         return vmx_read_guest_seg_base(to_vmx(vcpu), seg);
 }
 
-static int __vmx_get_cpl(struct kvm_vcpu *vcpu)
+static int vmx_get_cpl(struct kvm_vcpu *vcpu)
 {
+        struct vcpu_vmx *vmx = to_vmx(vcpu);
+
         if (!is_protmode(vcpu))
                 return 0;
 
@@ -3229,13 +3229,6 @@ static int __vmx_get_cpl(struct kvm_vcpu *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;
-}
-
-static int vmx_get_cpl(struct kvm_vcpu *vcpu)
-{
-        struct vcpu_vmx *vmx = to_vmx(vcpu);
-
         /*
          * If we enter real mode with cs.sel & 3 != 0, the normal CPL calculations
          * fail; use the cache instead.
@@ -3246,7 +3239,7 @@ static int vmx_get_cpl(struct kvm_vcpu *vcpu)
 
         if (!test_bit(VCPU_EXREG_CPL, (ulong *)&vcpu->arch.regs_avail)) {
                 __set_bit(VCPU_EXREG_CPL, (ulong *)&vcpu->arch.regs_avail);
-                vmx->cpl = __vmx_get_cpl(vcpu);
+                vmx->cpl = vmx_read_guest_seg_selector(vmx, VCPU_SREG_CS) & 3;
         }
 
         return vmx->cpl;