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=-12.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 EC6DCC433DF for ; Fri, 31 Jul 2020 06:30:13 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (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 C26AE208E4 for ; Fri, 31 Jul 2020 06:30:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C26AE208E4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 6C38086A32; Fri, 31 Jul 2020 06:30:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Q-IkIG6a8JAs; Fri, 31 Jul 2020 06:30:12 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id C666C86A14; Fri, 31 Jul 2020 06:30:12 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id ADAB3C0050; Fri, 31 Jul 2020 06:30:12 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9F40DC004D for ; Fri, 31 Jul 2020 06:30:11 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 936058863B for ; Fri, 31 Jul 2020 06:30:11 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ohGj6Bwh1d-E for ; Fri, 31 Jul 2020 06:30:10 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by whitealder.osuosl.org (Postfix) with ESMTPS id A2B7D88638 for ; Fri, 31 Jul 2020 06:30:10 +0000 (UTC) IronPort-SDR: 3LXu2QWw12Zob5cz3Ck2QkROf5k1vDaIHjyFvuxVAwAXqGqHhjwpCl0Ud9MzrgQH4cqR6ha/u/ 7+IrxqHo4G8g== X-IronPort-AV: E=McAfee;i="6000,8403,9698"; a="236601927" X-IronPort-AV: E=Sophos;i="5.75,417,1589266800"; d="scan'208";a="236601927" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jul 2020 23:30:09 -0700 IronPort-SDR: zX0i7UjX9khEP8dd1fClb0ZgGv4jktjUAWeeAPNWqdnllhKOSoYF4zKfKXMGsBk6HaRnhUzDgA XHE5s3SdIx7g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,417,1589266800"; d="scan'208";a="321320272" Received: from daisygao-mobl.ccr.corp.intel.com (HELO [10.254.211.68]) ([10.254.211.68]) by orsmga008.jf.intel.com with ESMTP; 30 Jul 2020 23:30:04 -0700 Subject: Re: [PATCH v3 3/4] iommu: Add iommu_aux_get_domain_for_dev() To: Alex Williamson References: <20200714055703.5510-1-baolu.lu@linux.intel.com> <20200714055703.5510-4-baolu.lu@linux.intel.com> <20200729142507.182cd18a@x1.home> From: Lu Baolu Message-ID: <06fd91c1-a978-d526-7e2b-fec619a458e4@linux.intel.com> Date: Fri, 31 Jul 2020 14:30:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200729142507.182cd18a@x1.home> Content-Language: en-US Cc: Jean-Philippe Brucker , Kevin Tian , Dave Jiang , Ashok Raj , kvm@vger.kernel.org, Cornelia Huck , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Alex, On 2020/7/30 4:25, Alex Williamson wrote: > On Tue, 14 Jul 2020 13:57:02 +0800 > Lu Baolu wrote: > >> The device driver needs an API to get its aux-domain. A typical usage >> scenario is: >> >> unsigned long pasid; >> struct iommu_domain *domain; >> struct device *dev = mdev_dev(mdev); >> struct device *iommu_device = vfio_mdev_get_iommu_device(dev); >> >> domain = iommu_aux_get_domain_for_dev(dev); >> if (!domain) >> return -ENODEV; >> >> pasid = iommu_aux_get_pasid(domain, iommu_device); >> if (pasid <= 0) >> return -EINVAL; >> >> /* Program the device context */ >> .... >> >> This adds an API for such use case. >> >> Suggested-by: Alex Williamson >> Signed-off-by: Lu Baolu >> --- >> drivers/iommu/iommu.c | 18 ++++++++++++++++++ >> include/linux/iommu.h | 7 +++++++ >> 2 files changed, 25 insertions(+) >> >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >> index cad5a19ebf22..434bf42b6b9b 100644 >> --- a/drivers/iommu/iommu.c >> +++ b/drivers/iommu/iommu.c >> @@ -2817,6 +2817,24 @@ void iommu_aux_detach_group(struct iommu_domain *domain, >> } >> EXPORT_SYMBOL_GPL(iommu_aux_detach_group); >> >> +struct iommu_domain *iommu_aux_get_domain_for_dev(struct device *dev) >> +{ >> + struct iommu_domain *domain = NULL; >> + struct iommu_group *group; >> + >> + group = iommu_group_get(dev); >> + if (!group) >> + return NULL; >> + >> + if (group->aux_domain_attached) >> + domain = group->domain; > Why wouldn't the aux domain flag be on the domain itself rather than > the group? Then if we wanted sanity checking in patch 1/ we'd only > need to test the flag on the object we're provided. Agreed. Given that a group may contain both non-aux and aux devices, adding such flag in iommu_group doesn't make sense. > > If we had such a flag, we could create an iommu_domain_is_aux() > function and then simply use iommu_get_domain_for_dev() and test that > it's an aux domain in the example use case. It seems like that would > resolve the jump from a domain to an aux-domain just as well as adding > this separate iommu_aux_get_domain_for_dev() interface. The is_aux > test might also be useful in other cases too. Let's rehearsal our use case. unsigned long pasid; struct iommu_domain *domain; struct device *dev = mdev_dev(mdev); struct device *iommu_device = vfio_mdev_get_iommu_device(dev); [1] domain = iommu_get_domain_for_dev(dev); if (!domain) return -ENODEV; [2] pasid = iommu_aux_get_pasid(domain, iommu_device); if (pasid <= 0) return -EINVAL; /* Program the device context */ .... The reason why I add this iommu_aux_get_domain_for_dev() is that we need to make sure the domain got at [1] is valid to be used at [2]. https://lore.kernel.org/linux-iommu/20200707150408.474d81f1@x1.home/ When calling into iommu_aux_get_pasid(), the iommu driver should make sure that @domain is a valid aux-domain for @iommu_device. Hence, for our use case, it seems that there's no need for a is_aux_domain() api. Anyway, I'm not against adding a new is_aux_domain() api if there's a need elsewhere. Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu