KVM: VMX: Preserve segment limit and access rights in real mode

While this is undocumented, real processors do not reload the segment
limit and access rights when loading a segment register in real mode.
Real programs rely on it so we need to comply with this behaviour.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 0d6872621ab..6e6421aeca0 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3113,6 +3113,9 @@ static void vmx_get_segment(struct kvm_vcpu *vcpu,
                 if (seg == VCPU_SREG_TR
                     || var->selector == vmx_read_guest_seg_selector(vmx, seg))
                         return;
+                var->base = vmx_read_guest_seg_base(vmx, seg);
+                var->selector = vmx_read_guest_seg_selector(vmx, seg);
+                return;
         }
         var->base = vmx_read_guest_seg_base(vmx, seg);
         var->limit = vmx_read_guest_seg_limit(vmx, seg);