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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 A025AC3A5A1 for ; Wed, 21 Aug 2019 15:36:37 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 7F8DE2339E for ; Wed, 21 Aug 2019 15:36:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F8DE2339E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 67863EED; Wed, 21 Aug 2019 15:36:37 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 3CA8CEE6 for ; Wed, 21 Aug 2019 15:36:36 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id DA72B822 for ; Wed, 21 Aug 2019 15:36:35 +0000 (UTC) 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 7FCBC337; Wed, 21 Aug 2019 08:36:35 -0700 (PDT) Received: from [10.1.197.57] (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 502633F718; Wed, 21 Aug 2019 08:36:34 -0700 (PDT) Subject: Re: [PATCH v2 2/8] iommu/arm-smmu-v3: Disable detection of ATS and PRI To: Will Deacon , iommu@lists.linux-foundation.org References: <20190821151749.23743-1-will@kernel.org> <20190821151749.23743-3-will@kernel.org> From: Robin Murphy Message-ID: Date: Wed, 21 Aug 2019 16:36:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190821151749.23743-3-will@kernel.org> Content-Language: en-GB Cc: Jean-Philippe Brucker , stable@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On 21/08/2019 16:17, Will Deacon wrote: > Detecting the ATS capability of the SMMU at probe time introduces a > spinlock into the ->unmap() fast path, even when ATS is not actually > in use. Furthermore, the ATC invalidation that exists is broken, as it > occurs before invalidation of the main SMMU TLB which leaves a window > where the ATC can be repopulated with stale entries. > > Given that ATS is both a new feature and a specialist sport, disable it > for now whilst we fix it properly in subsequent patches. Since PRI > requires ATS, disable that too. > > Cc: > Fixes: 9ce27afc0830 ("iommu/arm-smmu-v3: Add support for PCI ATS") Acked-by: Robin Murphy > Signed-off-by: Will Deacon > --- > drivers/iommu/arm-smmu-v3.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c > index 3402b1bc8e94..7a368059cd7d 100644 > --- a/drivers/iommu/arm-smmu-v3.c > +++ b/drivers/iommu/arm-smmu-v3.c > @@ -3295,11 +3295,13 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu) > } > > /* Boolean feature flags */ > +#if 0 /* ATS invalidation is slow and broken */ > if (IS_ENABLED(CONFIG_PCI_PRI) && reg & IDR0_PRI) > smmu->features |= ARM_SMMU_FEAT_PRI; > > if (IS_ENABLED(CONFIG_PCI_ATS) && reg & IDR0_ATS) > smmu->features |= ARM_SMMU_FEAT_ATS; > +#endif > > if (reg & IDR0_SEV) > smmu->features |= ARM_SMMU_FEAT_SEV; > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu