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=-9.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 8A582C433E1 for ; Thu, 25 Mar 2021 09:54:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4AC2961A27 for ; Thu, 25 Mar 2021 09:54:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230008AbhCYJyZ (ORCPT ); Thu, 25 Mar 2021 05:54:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:44322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229519AbhCYJyL (ORCPT ); Thu, 25 Mar 2021 05:54:11 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B76D261A14; Thu, 25 Mar 2021 09:54:10 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lPMgq-003hlA-Kp; Thu, 25 Mar 2021 09:54:08 +0000 Date: Thu, 25 Mar 2021 09:54:07 +0000 Message-ID: <874kgzsgn4.wl-maz@kernel.org> From: Marc Zyngier To: Shameerali Kolothum Thodi Cc: "kvmarm@lists.cs.columbia.edu" , "kvm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "stable@vger.kernel.org" , "pbonzini@redhat.com" , Linuxarm Subject: Re: [PATCH for-stable-5.10 2/2] KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility In-Reply-To: <3ed860eaf93c43969b7dfeb0904efb2e@huawei.com> References: <20210325091424.26348-1-shameerali.kolothum.thodi@huawei.com> <20210325091424.26348-3-shameerali.kolothum.thodi@huawei.com> <9850fc39c1c80840ea77eba60ee5e663@kernel.org> <3ed860eaf93c43969b7dfeb0904efb2e@huawei.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: shameerali.kolothum.thodi@huawei.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org, pbonzini@redhat.com, linuxarm@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 25 Mar 2021 09:37:15 +0000, Shameerali Kolothum Thodi wrote: > > > > > -----Original Message----- > > From: Marc Zyngier [mailto:maz@kernel.org] > > Sent: 25 March 2021 09:33 > > To: Shameerali Kolothum Thodi > > Cc: kvmarm@lists.cs.columbia.edu; kvm@vger.kernel.org; > > linux-arm-kernel@lists.infradead.org; stable@vger.kernel.org; > > pbonzini@redhat.com; Linuxarm > > Subject: Re: [PATCH for-stable-5.10 2/2] KVM: arm64: Workaround firmware > > wrongly advertising GICv2-on-v3 compatibility > > > > On 2021-03-25 09:14, Shameer Kolothum wrote: > > > From: Marc Zyngier > > > > > > commit 9739f6ef053f104a997165701c6e15582c4307ee upstream. > > > > > > It looks like we have broken firmware out there that wrongly > > > advertises a GICv2 compatibility interface, despite the CPUs not being > > > able to deal with it. > > > > > > To work around this, check that the CPU initialising KVM is actually > > > able to switch to MMIO instead of system registers, and use that as a > > > precondition to enable GICv2 compatibility in KVM. > > > > > > Note that the detection happens on a single CPU. If the firmware is > > > lying *and* that the CPUs are asymetric, all hope is lost anyway. > > > > > > Cc: stable@vger.kernel.org #5.10 > > > Reported-by: Shameerali Kolothum Thodi > > > > > > Tested-by: Shameer Kolothum > > > Signed-off-by: Marc Zyngier > > > Message-Id: <20210305185254.3730990-8-maz@kernel.org> > > > Signed-off-by: Paolo Bonzini > > > Signed-off-by: Shameer Kolothum > > > > Please hold on on that. > > > > This patch causes a regression, and needs a fix that is currently queued for 5.12 > > [1]. Once this hits upstream, please add the fix to the series and post it as a > > whole. > > Ok. Yes, I noted that. But was thinking if this goes through first > and then we can have a stable tag for that one, we can manage > it. The problem is we'd end-up with 5.10 being subtly broken for a while, and I want to avoid this. Specially given that not having this series only affects broken platforms, while having an incomplete series breaks working systems (which is be counter productive). > Anyway, will wait now. Thanks for that, M. -- Without deviation from the norm, progress is not possible.