[PATCH 3.16 14/63] KVM: x86: Emulator ignores LDTR/TR extended base on LLDT/LTR

[Ben Hutchings]

3.16.58-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nadav Amit <namit@xxxxxxxxxxxxxxxxx>

commit e37a75a13cdae5deaa2ea2cbf8d55b5dd08638b6 upstream.

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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/x86/kvm/emulate.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1467,6 +1467,7 @@ static int __load_segment_descriptor(str
 	ulong desc_addr;
 	int ret;
 	u16 dummy;
+	u32 base3 = 0;
 
 	memset(&seg_desc, 0, sizeof seg_desc);
 
@@ -1597,9 +1598,14 @@ static int __load_segment_descriptor(str
 		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);
 	if (desc)
 		*desc = seg_desc;
 	return X86EMUL_CONTINUE;