From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Rusty Russell" <rusty.russell@linaro.org>
Subject: [PATCH] ARM: KVM: Emulate ID_DFR0 to say we don't support anything.
Date: Fri, 23 Mar 2012 11:08:49 +1030
Message-ID: <87obro882u.fsf@rustcorp.com.au>
References: <4F590411.9060201@arm.com> <87ty1g88dv.fsf@rustcorp.com.au>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: android-virt@lists.cs.columbia.edu, kvm@vger.kernel.org
To: Marc Zyngier <marc.zyngier@arm.com>,
	Christoffer Dall <c.dall@virtualopensystems.com>,
	Peter Maydell <Peter.Maydell@arm.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from ozlabs.org ([203.10.76.45]:41679 "EHLO ozlabs.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1755669Ab2CWAoV (ORCPT <rfc822;kvm@vger.kernel.org>);
	Thu, 22 Mar 2012 20:44:21 -0400
In-Reply-To: <87ty1g88dv.fsf@rustcorp.com.au>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

The guest should be checking this before trying to use performance monitors,
for example.

Signed-off-by: Rusty Russell <rusty.russell@linaro.org>

diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
index e356d1c..c07eb2b 100644
--- a/arch/arm/kvm/emulate.c
+++ b/arch/arm/kvm/emulate.c
@@ -238,6 +238,15 @@ static bool read_l2ctlr(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static bool read_id_dfr0(struct kvm_vcpu *vcpu,
+			 const struct coproc_params *p,
+			 unsigned long arg)
+{
+	/* We support no performance monitors (27-24 = b1111) and no debug */
+	*vcpu_reg(vcpu, p->Rt1) = 0x0F000000;
+	return true;
+}
+
 static bool access_cp15_reg(struct kvm_vcpu *vcpu,
 			    const struct coproc_params *p,
 			    unsigned long cp15_reg)
@@ -277,6 +286,9 @@ struct coproc_emulate {
 #define RW		.is_w  = DF
 
 static const struct coproc_emulate coproc_emulate[] = {
+	/* ID_DFR0 (guest asks what PMU/debug we support) */
+	{ CRn( 0), CRm( 1), Op1( 0), Op2( 2), is32,  READ,  read_id_dfr0},
+
 	/*
 	 * L2CTLR access:
 	 *