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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_2 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 11E83C47404 for ; Fri, 11 Oct 2019 13:33:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2E1A2089F for ; Fri, 11 Oct 2019 13:33:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570800829; bh=I0X2xZBI6wAsH7Mdzj2OAiDGMTUbQ3ll1WxfL05QE7g=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=TKcquf239gctcI2iRMnu3mRQAuXRt7v54UbkgirGDjprjW6ZOUrOgT3/uOmS6SpGy 0CWrbqVWf887KU2KsruL1OuT6O+KHA3WUOwooZE2kJz81etBUveYxcYTepurrbX3uL XbAVrk75txFkzJzHDXyfFoLyw8HMIlXkMXWcdi+s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728328AbfJKNdt (ORCPT ); Fri, 11 Oct 2019 09:33:49 -0400 Received: from inca-roads.misterjones.org ([213.251.177.50]:46759 "EHLO inca-roads.misterjones.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727709AbfJKNds (ORCPT ); Fri, 11 Oct 2019 09:33:48 -0400 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 1iIv3A-000788-Pa; Fri, 11 Oct 2019 15:33:44 +0200 Date: Fri, 11 Oct 2019 14:33:43 +0100 From: Marc Zyngier To: Mark Rutland Cc: Sai Prakash Ranjan , rnayak@codeaurora.org, suzuki.poulose@arm.com, catalin.marinas@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 Subject: Re: Relax CPU features sanity checking on heterogeneous architectures Message-ID: <20191011143343.541da66c@why> In-Reply-To: <20191011105010.GA29364@lakrids.cambridge.arm.com> References: <20191011105010.GA29364@lakrids.cambridge.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: mark.rutland@arm.com, saiprakash.ranjan@codeaurora.org, rnayak@codeaurora.org, suzuki.poulose@arm.com, catalin.marinas@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 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, 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). 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. M. -- Jazz is not dead. It just smells funny...