On Fri, Feb 03, 2012 at 07:29:24PM +0100, Kevin Wolf wrote:
> Keep CPL at 0 in real mode and at 3 in VM86. In protected/long mode, use
> RPL rather than DPL of the code segment.
>
> Signed-off-by: Kevin Wolf <kwolf@xxxxxxxxxx>
> ---
> arch/x86/kvm/svm.c | 19 ++++++++++++++++---
> 1 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 6a977c1..4124a7e 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1263,6 +1263,21 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
> wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
> }
>
> +static void svm_update_cpl(struct kvm_vcpu *vcpu)
> +{
> + struct vcpu_svm *svm = to_svm(vcpu);
> + int cpl;
> +
> + if (!is_protmode(vcpu))
> + cpl = 0;
> + else if (svm->vmcb->save.rflags & X86_EFLAGS_VM)
> + cpl = 3;
> + else
> + cpl = svm->vmcb->save.cs.selector & 0x3;
> +
> + svm->vmcb->save.cpl = cpl;
> +}
> +
As you probably know already I think cpl should be updated in
svm_get_rflags() too. With current patch restoring CS segment
register before rflags register after migration may cause cpl
to get wrong value for instance.
> static unsigned long svm_get_rflags(struct kvm_vcpu *vcpu)
> {
> return to_svm(vcpu)->vmcb->save.rflags;
> @@ -1538,9 +1553,7 @@ static void svm_set_segment(struct kvm_vcpu *vcpu,
> s->attrib |= (var->g & 1) << SVM_SELECTOR_G_SHIFT;
> }
> if (seg == VCPU_SREG_CS)
> - svm->vmcb->save.cpl
> - = (svm->vmcb->save.cs.attrib
> - >> SVM_SELECTOR_DPL_SHIFT) & 3;
> + svm_update_cpl(vcpu);
>
> mark_dirty(svm->vmcb, VMCB_SEG);
> }
> --
> 1.7.6.5
--
Gleb.
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