KVM: fix sil/dil/bpl/spl in the mod/rm fields

The x86-64 extended low-byte registers were fetched correctly from reg,
but not from mod/rm.

This fixes another bug in the boot of RHEL5.9 64-bit, but it is still
not enough.

Cc: <stable@vger.kernel.org> # 3.9
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 0f42c2a..5953dce 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1240,9 +1240,12 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
        ctxt->modrm_seg = VCPU_SREG_DS;
 
        if (ctxt->modrm_mod == 3) {
+               int highbyte_regs = ctxt->rex_prefix == 0;
+
                op->type = OP_REG;
                op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
-               op->addr.reg = decode_register(ctxt, ctxt->modrm_rm, ctxt->d & ByteOp);
+               op->addr.reg = decode_register(ctxt, ctxt->modrm_rm,
+                                              highbyte_regs && (ctxt->d & ByteOp));
                if (ctxt->d & Sse) {
                        op->type = OP_XMM;
                        op->bytes = 16;