From patchwork Mon May 23 12:37:02 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Zyngier X-Patchwork-Id: 9131737 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 19E39607D3 for ; Mon, 23 May 2016 12:39:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0DD9428221 for ; Mon, 23 May 2016 12:39:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 02BB228236; Mon, 23 May 2016 12:39:48 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 843C628221 for ; Mon, 23 May 2016 12:39:47 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1b4p7z-00074X-31; Mon, 23 May 2016 12:38:35 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1b4p7L-0006SO-2c for linux-arm-kernel@lists.infradead.org; Mon, 23 May 2016 12:37:56 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3EB3C448; Mon, 23 May 2016 05:37:40 -0700 (PDT) Received: from approximate.cambridge.arm.com (approximate.cambridge.arm.com [10.1.209.129]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7757A3F246; Mon, 23 May 2016 05:37:17 -0700 (PDT) From: Marc Zyngier To: Christoffer Dall Subject: [PATCH 6/7] arm64: KVM: vgic-v3: Prevent the guest from messing with ICC_SRE_EL1 Date: Mon, 23 May 2016 13:37:02 +0100 Message-Id: <1464007023-11736-7-git-send-email-marc.zyngier@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1464007023-11736-1-git-send-email-marc.zyngier@arm.com> References: <1464007023-11736-1-git-send-email-marc.zyngier@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160523_053755_243625_FF231214 X-CRM114-Status: UNSURE ( 9.46 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Both our GIC emulations are "strict", in the sense that we either emulate a GICv2 or a GICv3, and not a GICv3 with GICv2 legacy support. But when running on a GICv3 host, we still allow the guest to tinker with the ICC_SRE_EL1 register during its time slice: it can switch SRE off, observe that it is off, and yet on the next world switch, find the SRE bit to be set again. Not very nice. An obvious solution is to always trap accesses to ICC_SRE_EL1 (by clearing ICC_SRE_EL2.Enable), and to let the handler return the programmed value on a read, or ignore the write. That way, the guest can always observe that our GICv3 is SRE==1 only. Signed-off-by: Marc Zyngier Reviewed-by: Christoffer Dall --- arch/arm64/kvm/hyp/vgic-v3-sr.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c b/arch/arm64/kvm/hyp/vgic-v3-sr.c index 3129df9..40c3b4c 100644 --- a/arch/arm64/kvm/hyp/vgic-v3-sr.c +++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c @@ -313,10 +313,8 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu) * Prevent the guest from touching the GIC system registers if * SRE isn't enabled for GICv3 emulation. */ - if (!cpu_if->vgic_sre) { - write_gicreg(read_gicreg(ICC_SRE_EL2) & ~ICC_SRE_EL2_ENABLE, - ICC_SRE_EL2); - } + write_gicreg(read_gicreg(ICC_SRE_EL2) & ~ICC_SRE_EL2_ENABLE, + ICC_SRE_EL2); } void __hyp_text __vgic_v3_init_lrs(void)