KVM: x86 emulator: implement LTR

Opcode 0F 00 /3.  Encountered during Windows XP secondary processor bringup.

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

1 files changed, 10 insertions, 1 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 92a1adde0b44..97d9a9914ba8 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3033,6 +3033,15 @@ static int em_lldt(struct x86_emulate_ctxt *ctxt)
         return load_segment_descriptor(ctxt, sel, VCPU_SREG_LDTR);
 }
 
+static int em_ltr(struct x86_emulate_ctxt *ctxt)
+{
+        u16 sel = ctxt->src.val;
+
+        /* Disable writeback. */
+        ctxt->dst.type = OP_NONE;
+        return load_segment_descriptor(ctxt, sel, VCPU_SREG_TR);
+}
+
 static int em_invlpg(struct x86_emulate_ctxt *ctxt)
 {
         int rc;
@@ -3579,7 +3588,7 @@ static struct opcode group6[] = {
         DI(Prot,        sldt),
         DI(Prot,        str),
         II(Prot | Priv | SrcMem16, em_lldt, lldt),
-        DI(Prot | Priv, ltr),
+        II(Prot | Priv | SrcMem16, em_ltr, ltr),
         N, N, N, N,
 };