From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E2D60C33CA9 for ; Mon, 13 Jan 2020 16:31:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF992214AF for ; Mon, 13 Jan 2020 16:31:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728977AbgAMQbm (ORCPT ); Mon, 13 Jan 2020 11:31:42 -0500 Received: from foss.arm.com ([217.140.110.172]:41536 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726567AbgAMQbl (ORCPT ); Mon, 13 Jan 2020 11:31:41 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3EC1011B3; Mon, 13 Jan 2020 08:31:41 -0800 (PST) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A69683F534; Mon, 13 Jan 2020 08:31:40 -0800 (PST) Date: Mon, 13 Jan 2020 16:31:38 +0000 From: Andrew Murray To: Marc Zyngier Cc: Catalin Marinas , Will Deacon , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Sudeep Holla , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 10/18] arm64: KVM/debug: use EL1&0 stage 1 translation regime Message-ID: <20200113163138.GP42593@e119886-lin.cambridge.arm.com> References: <20191220143025.33853-1-andrew.murray@arm.com> <20191220143025.33853-11-andrew.murray@arm.com> <86d0cgir74.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <86d0cgir74.wl-maz@kernel.org> User-Agent: Mutt/1.10.1+81 (426a6c1) (2018-08-26) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 22, 2019 at 10:34:55AM +0000, Marc Zyngier wrote: > On Fri, 20 Dec 2019 14:30:17 +0000, > Andrew Murray wrote: > > > > From: Sudeep Holla > > > > Now that we have all the save/restore mechanism in place, lets enable > > the translation regime used by buffer from EL2 stage 1 to EL1 stage 1 > > on VHE systems. > > > > Signed-off-by: Sudeep Holla > > [ Reword commit, don't trap to EL2 ] > > Not trapping to EL2 for the case where we don't allow SPE in the > guest is not acceptable. > > > Signed-off-by: Andrew Murray > > --- > > arch/arm64/kvm/hyp/switch.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > > index 67b7c160f65b..6c153b79829b 100644 > > --- a/arch/arm64/kvm/hyp/switch.c > > +++ b/arch/arm64/kvm/hyp/switch.c > > @@ -100,6 +100,7 @@ static void activate_traps_vhe(struct kvm_vcpu *vcpu) > > > > write_sysreg(val, cpacr_el1); > > > > + write_sysreg(vcpu->arch.mdcr_el2 | 3 << MDCR_EL2_E2PB_SHIFT, mdcr_el2); > > write_sysreg(kvm_get_hyp_vector(), vbar_el1); > > } > > NOKPROBE_SYMBOL(activate_traps_vhe); > > @@ -117,6 +118,7 @@ static void __hyp_text __activate_traps_nvhe(struct kvm_vcpu *vcpu) > > __activate_traps_fpsimd32(vcpu); > > } > > > > + write_sysreg(vcpu->arch.mdcr_el2 | 3 << MDCR_EL2_E2PB_SHIFT, mdcr_el2); > > There is a _MASK macro that can replace this '3', and is in keeping > with the rest of the code. > > It still remains that it looks like the wrong place to do this, and > vcpu_load seems much better. Why should you write to mdcr_el2 on each > entry to the guest, since you know whether it has SPE enabled at the > point where it gets scheduled? For nVHE, the only reason we'd want to change E2PB on entry/exit of guest would be if the host is also using SPE. If the host is using SPE whilst the vcpu is 'loaded' but we're not in the guest, then host SPE could raise an interrupt - we need the E2PB bits to allow access from EL1 (host). Thanks, Andrew Murray > > M. > > -- > Jazz is not dead, it just smells funny.