KVM: x86: Emulator should set DR6 upon GD like real CPU

It should clear B0-B3 and set BD.

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 a4703eb..736a49f 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3588,8 +3588,15 @@ static int check_dr_read(struct x86_emulate_ctxt *ctxt)
        if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5))
                return emulate_ud(ctxt);
 
-       if (check_dr7_gd(ctxt))
+       if (check_dr7_gd(ctxt)) {
+               ulong dr6;
+
+               ctxt->ops->get_dr(ctxt, 6, &dr6);
+               dr6 &= ~15;
+               dr6 |= DR6_BD | DR6_RTM;
+               ctxt->ops->set_dr(ctxt, 6, dr6);
                return emulate_db(ctxt);
+       }
 
        return X86EMUL_CONTINUE;
 }