KVM: x86: Emulator ignores LDTR/TR extended base on LLDT/LTR

The current implementation ignores the LDTR/TR base high 32-bits on long-mode.
As a result the loaded segment descriptor may be incorrect.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8ec4a3e..136088f 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1422,6 +1422,7 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
        ulong desc_addr;
        int ret;
        u16 dummy;
+       u32 base3 = 0;
 
        memset(&seg_desc, 0, sizeof seg_desc);
 
@@ -1538,9 +1539,14 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
                ret = write_segment_descriptor(ctxt, selector, &seg_desc);
                if (ret != X86EMUL_CONTINUE)
                        return ret;
+       } else if (ctxt->mode == X86EMUL_MODE_PROT64) {
+               ret = ctxt->ops->read_std(ctxt, desc_addr+8, &base3,
+                               sizeof(base3), &ctxt->exception);
+               if (ret != X86EMUL_CONTINUE)
+                       return ret;
        }
 load:
-       ctxt->ops->set_segment(ctxt, selector, &seg_desc, 0, seg);
+       ctxt->ops->set_segment(ctxt, selector, &seg_desc, base3, seg);
        return X86EMUL_CONTINUE;
 exception:
        emulate_exception(ctxt, err_vec, err_code, true);