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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 1E411C33CB7 for ; Mon, 20 Jan 2020 02:47:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9C0720678 for ; Mon, 20 Jan 2020 02:47:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="OswGjo+E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729064AbgATCr0 (ORCPT ); Sun, 19 Jan 2020 21:47:26 -0500 Received: from mail25.static.mailgun.info ([104.130.122.25]:61234 "EHLO mail25.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728946AbgATCrZ (ORCPT ); Sun, 19 Jan 2020 21:47:25 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1579488445; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=VMIU6qr3Wgt3xkflneQ7e/aD1ybOQyncDm4GEzhwaY8=; b=OswGjo+Ez8QO3NEVvrZiriUQvl1Yayt3E7cSV0eDs9dr6/PfumWtQBgEkTuQYA11DAE+TlS4 ahzUDDJAwkabnt8RW0PWhRPdf8lPABnteOgF5UOTP1ndeeMmhgwf7ctFomt8gw9n9i7yhonz NR3/xqAGBkKtz7NonHb0NjR9u9A= X-Mailgun-Sending-Ip: 104.130.122.25 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e2514b7.7f584f5d91b8-smtp-out-n02; Mon, 20 Jan 2020 02:47:19 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 73A3DC4479F; Mon, 20 Jan 2020 02:47:18 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id 9620CC43383; Mon, 20 Jan 2020 02:47:17 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 20 Jan 2020 08:17:17 +0530 From: Sai Prakash Ranjan To: Mark Rutland , Marc Zyngier , catalin.marinas@arm.com Cc: suzuki.poulose@arm.com, linux-kernel@vger.kernel.org, jeremy.linton@arm.com, bjorn.andersson@linaro.org, linux-arm-msm@vger.kernel.org, andrew.murray@arm.com, will@kernel.org, Dave.Martin@arm.com, linux-arm-kernel@lists.infradead.org, Stephen Boyd , Douglas Anderson Subject: Re: Relax CPU features sanity checking on heterogeneous architectures In-Reply-To: <20191011135431.GB33537@lakrids.cambridge.arm.com> References: <20191011105010.GA29364@lakrids.cambridge.arm.com> <20191011143343.541da66c@why> <20191011135431.GB33537@lakrids.cambridge.arm.com> Message-ID: X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mark, On 2019-10-11 19:24, Mark Rutland wrote: > On Fri, Oct 11, 2019 at 02:33:43PM +0100, Marc Zyngier wrote: >> On Fri, 11 Oct 2019 11:50:11 +0100 >> Mark Rutland wrote: >> >> > Hi, >> > >> > On Fri, Oct 11, 2019 at 11:19:00AM +0530, Sai Prakash Ranjan wrote: >> > > On latest QCOM SoCs like SM8150 and SC7180 with big.LITTLE arch, below >> > > warnings are observed during bootup of big cpu cores. >> > >> > For reference, which CPUs are in those SoCs? >> > >> > > SM8150: >> > > >> > > [ 0.271177] CPU features: SANITY CHECK: Unexpected variation in >> > > SYS_ID_AA64PFR0_EL1. Boot CPU: 0x00000011112222, CPU4: 0x00000011111112 >> > >> > The differing fields are EL3, EL2, and EL1: the boot CPU supports >> > AArch64 and AArch32 at those exception levels, while the secondary only >> > supports AArch64. >> > >> > Do we handle this variation in KVM? >> >> We do, at least at vcpu creation time (see kvm_reset_vcpu). But if one >> of the !AArch32 CPU comes in late in the game (after we've started a >> guest), all bets are off (we'll schedule the 32bit guest on that CPU, >> enter the guest, immediately take an Illegal Exception Return, and >> return to userspace with KVM_EXIT_FAIL_ENTRY). > > Ouch. We certainly can't remove the warning untill we deal with that > somehow, then. > >> Not sure we could do better, given the HW. My preference would be to >> fail these CPUs if they aren't present at boot time. > > I agree; I think we need logic to check the ID register fields against > their EXACT, {LOWER,HIGHER}_SAFE, etc rules regardless of whether we > have an associated cap. That can then abort a late onlining of a CPU > which violates those rules w.r.t. the finalised system value. > > I suspect that we may want to split the notion of > safe-for-{user,kernel-guest} in the feature tables, as if nothing else > it will force us to consider those cases separately when adding new > stuff. > I can help with testing these if you have any sample patches. Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation