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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 DDAAFC2D0C0 for ; Sat, 21 Dec 2019 13:12:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B186D2072B for ; Sat, 21 Dec 2019 13:12:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576933942; bh=Uk9W8Ar9Y9vziNp+Sn34RTMLJfeMXEOdRJQBR5/jPpA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=2m3rriXBLhsAFelg8C2APYB8t95sUIQnPPG47Fh8zIdYDu4mD2iut7j9uoblHopFf ZYMTRpakUfbwrr8U5Cao8vAnLJb/5zJf7eYa3vFfUNm0dabV1F+LA1sElQyxE/2whk wzR+mzZnuWupIALkJji3SRr09JHlE2/b1J02QFcM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726878AbfLUNMU (ORCPT ); Sat, 21 Dec 2019 08:12:20 -0500 Received: from inca-roads.misterjones.org ([213.251.177.50]:43494 "EHLO inca-roads.misterjones.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726583AbfLUNMT (ORCPT ); Sat, 21 Dec 2019 08:12:19 -0500 Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why) by cheepnis.misterjones.org with esmtpsa (TLSv1.2:AES256-GCM-SHA384:256) (Exim 4.80) (envelope-from ) id 1iieYK-0002tv-Gk; Sat, 21 Dec 2019 14:12:16 +0100 Date: Sat, 21 Dec 2019 13:12:14 +0000 From: Marc Zyngier To: Andrew Murray Cc: will@kernel.org, Catalin Marinas , 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 02/18] arm64: KVM: reset E2PB correctly in MDCR_EL2 when exiting the guest(VHE) Message-ID: <20191221131214.769a140e@why> In-Reply-To: <20191220143025.33853-3-andrew.murray@arm.com> References: <20191220143025.33853-1-andrew.murray@arm.com> <20191220143025.33853-3-andrew.murray@arm.com> Organization: Approximate X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: andrew.murray@arm.com, will@kernel.org, catalin.marinas@arm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, sudeep.holla@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on cheepnis.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Dec 2019 14:30:09 +0000 Andrew Murray wrote: > From: Sudeep Holla > > On VHE systems, the reset value for MDCR_EL2.E2PB=b00 which defaults > to profiling buffer using the EL2 stage 1 translations. Does the reset value actually matter here? I don't see it being specific to VHE systems, and all we're trying to achieve is to restore the SPE configuration to a state where it can be used by the host. > However if the > guest are allowed to use profiling buffers changing E2PB settings, we How can the guest be allowed to change E2PB settings? Or do you mean here that allowing the guest to use SPE will mandate changes of the E2PB settings, and that we'd better restore the hypervisor state once we exit? > need to ensure we resume back MDCR_EL2.E2PB=b00. Currently we just > do bitwise '&' with MDCR_EL2_E2PB_MASK which will retain the value. > > So fix it by clearing all the bits in E2PB. > > Signed-off-by: Sudeep Holla > Signed-off-by: Andrew Murray > --- > arch/arm64/kvm/hyp/switch.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index 72fbbd86eb5e..250f13910882 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c > @@ -228,9 +228,7 @@ void deactivate_traps_vhe_put(void) > { > u64 mdcr_el2 = read_sysreg(mdcr_el2); > > - mdcr_el2 &= MDCR_EL2_HPMN_MASK | > - MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT | > - MDCR_EL2_TPMS; > + mdcr_el2 &= MDCR_EL2_HPMN_MASK | MDCR_EL2_TPMS; > > write_sysreg(mdcr_el2, mdcr_el2); > I'm OK with this change, but I believe the commit message could use some tidying up. Thanks, M. -- Jazz is not dead. It just smells funny...