KVM: VMX: fix incorrect cached cpl value with real/v8086 modes (v3)

Marcelo Tosatti
2013-01-07T21:27:16Z

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 55dfc37..dd2a85c 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;