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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 92D27C433C1 for ; Wed, 24 Mar 2021 17:08:23 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1697C61A12 for ; Wed, 24 Mar 2021 17:08:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1697C61A12 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=LpbIFLOUZtoJ3A1GoAIijuXzE4IvDx8Lnl/n0MwBjO0=; b=A5jF4zq5cwCCj3gRmKuTmkYDB VmBUJS7AxiWr9PrsM3UgPN4fweYWmFeprgvK1FYyHmBastCX8NwPFuUwNgcCanW7F1LQwQfkni+oW Ap1fZIMBwB7sXY9WWeHiMX6Eit7yQfoh4Naa5Oj2TWDZuE44HqB2DgABR6lmBoVtEv5iweTILs3Ax AoSKZBPjLhL/e9XSqymOB+RLMVxscVmEW7Mqf6ykMPyye3xke3fLu5VZAudvscWFVW/I3lAac9hEe OoBw83ELlmz3HcHSM+dsIUA63WqV7rlTiyOtxlP+EZ1tzr5lQYl1QhIR36jtNBrVZwVtXlmj7Cf1x SSsXYNrFQ==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lP6yK-00HTo2-U2; Wed, 24 Mar 2021 17:07:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lP6yF-00HTmd-RC for linux-arm-kernel@lists.infradead.org; Wed, 24 Mar 2021 17:07:05 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7BE88ED1; Wed, 24 Mar 2021 10:07:01 -0700 (PDT) Received: from [10.57.51.32] (unknown [10.57.51.32]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E4B8D3F7D7; Wed, 24 Mar 2021 10:06:59 -0700 (PDT) Subject: Re: [PATCH v5 05/19] arm64: Add support for trace synchronization barrier To: Marc Zyngier Cc: Catalin Marinas , 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 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> From: Suzuki K Poulose Message-ID: <59aec851-e980-0a6d-8ba5-56a35fa5a7a9@arm.com> Date: Wed, 24 Mar 2021 17:06:58 +0000 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <87tup0ikf0.wl-maz@kernel.org> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210324_170704_265087_EB00BEC4 X-CRM114-Status: GOOD ( 25.75 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 24/03/2021 16:30, Marc Zyngier wrote: > On Wed, 24 Mar 2021 16:25:12 +0000, > Suzuki K Poulose wrote: >> >> On 24/03/2021 16:16, Marc Zyngier wrote: >>> On Wed, 24 Mar 2021 15:51:14 +0000, >>> Suzuki K Poulose wrote: >>>> >>>> On 24/03/2021 13:49, Marc Zyngier wrote: >>>>> On Wed, 24 Mar 2021 09:39:13 +0000, >>>>> Suzuki K Poulose wrote: >>>>>> >>>>>> On 23/03/2021 18:21, Catalin Marinas wrote: >>>>>>> Hi Suzuki? >>>>>>> >>>>>>> On Tue, Mar 23, 2021 at 12:06:33PM +0000, Suzuki K Poulose wrote: >>>>>>>> tsb csync synchronizes the trace operation of instructions. >>>>>>>> The instruction is a nop when FEAT_TRF is not implemented. >>>>>>>> >>>>>>>> Cc: Mathieu Poirier >>>>>>>> Cc: Mike Leach >>>>>>>> Cc: Catalin Marinas >>>>>>>> Cc: Will Deacon >>>>>>>> Signed-off-by: Suzuki K Poulose >>>>>>> >>>>>>> How do you plan to merge these patches? If they go via the coresight >>>>>>> tree: >>>>>>> >>>>>> >>>>>> Ideally all of this should go via the CoreSight tree to have the >>>>>> dependencies solved at one place. But there are some issues : >>>>>> >>>>>> If this makes to 5.13 queue for CoreSight, >>>>>> >>>>>> 1) CoreSight next is based on rc2 at the moment and we have fixes gone >>>>>> into rc3 and later, which this series will depend on. (We could move >>>>>> the next tree forward to a later rc to solve this). >>>>>> >>>>>> 2) There could be conflicts with the kvmarm tree for the KVM host >>>>>> changes (That has dependency on the TRBE definitions patch). >>>>>> >>>>>> If it doesn't make to 5.13 queue, it would be good to have this patch, >>>>>> the TRBE defintions and the KVM host patches queued for 5.13 (not sure >>>>>> if this is acceptable) and we could rebase the CoreSight changes on 5.13 >>>>>> and push it to next release. >>>>>> >>>>>> I am open for other suggestions. >>>>>> >>>>>> Marc, Mathieu, >>>>>> >>>>>> Thoughts ? >>>>> >>>>> I was planning to take the first two patches in 5.12 as fixes (they >>>>> are queued already, and would hopefully land in -rc5). If that doesn't >>>>> fit with the plan, please let me know ASAP. >>>> >>>> Marc, >>>> >>>> I think it would be better to hold on pushing those patches until we >>>> have a clarity on how things will go. >>> >>> OK. I thought there was a need for these patches to prevent guest >>> access to the v8.4 self hosted tracing feature that went in 5.12 >>> though[1]... Did I get it wrong? >> >> Yes, that is correct. The guest could access the Trace Filter Control >> register and fiddle with the host settings, without this patch. >> e.g, it could disable tracing at EL0/EL1, without the host being >> aware on nVHE host. > > 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. Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel