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,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 733CCC433E1 for ; Wed, 24 Mar 2021 17:41:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 296B961A23 for ; Wed, 24 Mar 2021 17:41:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237203AbhCXRlC (ORCPT ); Wed, 24 Mar 2021 13:41:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:56800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237166AbhCXRks (ORCPT ); Wed, 24 Mar 2021 13:40:48 -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 1522A61A15; Wed, 24 Mar 2021 17:40:48 +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 1lP7Ur-003ZgH-SX; Wed, 24 Mar 2021 17:40:46 +0000 Date: Wed, 24 Mar 2021 17:40:39 +0000 Message-ID: <877dlwsb54.wl-maz@kernel.org> From: Marc Zyngier To: Catalin Marinas , Suzuki K Poulose Cc: Mathieu Poirier , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, mike.leach@linaro.org, leo.yan@linaro.org, anshuman.khandual@arm.com, Will Deacon Subject: Re: [PATCH v5 05/19] arm64: Add support for trace synchronization barrier In-Reply-To: <20210324171934.GB3709@arm.com> References: <20210323120647.454211-1-suzuki.poulose@arm.com> <20210323120647.454211-6-suzuki.poulose@arm.com> <20210323182142.GA16080@arm.com> <7675ab71-c2ff-91e0-5728-fcb216ac1e0d@arm.com> <875z1gk6fo.wl-maz@kernel.org> <1b5e5bb2-b89f-fa35-0a8b-8c5476cb9ff6@arm.com> <871rc4jzn0.wl-maz@kernel.org> <17e57b01-840b-dbeb-c09f-1c04becb8749@arm.com> <87tup0ikf0.wl-maz@kernel.org> <59aec851-e980-0a6d-8ba5-56a35fa5a7a9@arm.com> <20210324171934.GB3709@arm.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: catalin.marinas@arm.com, suzuki.poulose@arm.com, mathieu.poirier@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, coresight@lists.linaro.org, mike.leach@linaro.org, leo.yan@linaro.org, anshuman.khandual@arm.com, will.deacon@arm.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: linux-kernel@vger.kernel.org On Wed, 24 Mar 2021 17:19:36 +0000, Catalin Marinas wrote: > > On Wed, Mar 24, 2021 at 05:06:58PM +0000, Suzuki K Poulose wrote: > > On 24/03/2021 16:30, Marc Zyngier wrote: > > > > > > OK, so we definitely do need these patches, don't we? Both? Just one? > > > Please have a look at kvmarm/fixes and tell me what I must keep. > > > > Both of them are fixes. > > > > commit "KVM: arm64: Disable guest access to trace filter controls" > > - This fixes guest fiddling with the trace filter control as described > > above. > > > > commit "KVM: arm64: Hide system instruction access to Trace registers" > > - Fixes the Hypervisor to advertise what it doesn't support. i.e > > stop advertising trace system instruction access to a guest. > > Otherwise a guest which trusts the ID registers > > (ID_AA64DFR0_EL1.TRACEVER == 1) can crash while trying to access the > > trace register as we trap the accesses (CPTR_EL2.TTA == 1). On Linux, > > the ETM drivers need a DT explicitly advertising the support. So, > > this is not immediately impacted. And this fix goes a long way back > > in the history, when the CPTR_EL2.TTA was added. > > > > Now, the reason for asking you to hold on is the way this could create > > conflicts in merging the rest of the series. > > The way we normally work around this is to either rebase your series on > top of -rc5 when the fixes go in or, if you want an earlier -rc base, > Marc can put them on a stable branch somewhere that you can use. Here's what I've done: - the two patches are now on a branch[1] based off -rc3 which I officially declare stable. Feel free to rebase your series on top. - the KVM fixes branch now embeds this branch (yes, I've rebased it -- we'll hopefully survive the outrage). Thanks, M. [1] https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git/log/?h=trace-fixes-5.12 -- Without deviation from the norm, progress is not possible.