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=-8.5 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 A41A9C433E0 for ; Thu, 25 Jun 2020 12:54:29 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 7285C204EA for ; Thu, 25 Jun 2020 12:54:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7285C204EA 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 whitealder.osuosl.org (Postfix) with ESMTP id 48D2786905; Thu, 25 Jun 2020 12:54:29 +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 s3AMEAEthf56; Thu, 25 Jun 2020 12:54:28 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id 6A32D86091; Thu, 25 Jun 2020 12:54:28 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 4D3A0C088E; Thu, 25 Jun 2020 12:54:28 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0B019C016F for ; Thu, 25 Jun 2020 12:54:27 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id EE673868E5 for ; Thu, 25 Jun 2020 12:54:26 +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 5fdUFuPZvn4i for ; Thu, 25 Jun 2020 12:54:26 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by whitealder.osuosl.org (Postfix) with ESMTPS id 3BCFC86091 for ; Thu, 25 Jun 2020 12:54:26 +0000 (UTC) IronPort-SDR: KgIAc3Hf2rKjzDe3sCI1cC16lPXIy281uuPZcHx2c8yenEZubab7xdFY/1S4XbbT7ouWV6N74j pnPglmaMLFlw== X-IronPort-AV: E=McAfee;i="6000,8403,9662"; a="143962333" X-IronPort-AV: E=Sophos;i="5.75,279,1589266800"; d="scan'208";a="143962333" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2020 05:54:25 -0700 IronPort-SDR: 604t9fzSsToorAiXk1e2QV9ssp+DA11lpkBgLXjc441qtWdtpCW7bq++NhHiVciHxVJKCHpF1O AKsWP6VHxW3Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,279,1589266800"; d="scan'208";a="263914182" Received: from blu2-mobl3.ccr.corp.intel.com (HELO [10.255.28.52]) ([10.255.28.52]) by fmsmga007.fm.intel.com with ESMTP; 25 Jun 2020 05:54:23 -0700 Subject: Re: [PATCH 7/7] iommu/vt-d: Disable multiple GPASID-dev bind To: Jacob Pan , iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse References: <1592926996-47914-1-git-send-email-jacob.jun.pan@linux.intel.com> <1592926996-47914-8-git-send-email-jacob.jun.pan@linux.intel.com> From: Lu Baolu Message-ID: Date: Thu, 25 Jun 2020 20:54:22 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <1592926996-47914-8-git-send-email-jacob.jun.pan@linux.intel.com> Content-Language: en-US Cc: "Tian, Kevin" , Raj Ashok 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" On 2020/6/23 23:43, Jacob Pan wrote: > For the unlikely use case where multiple aux domains from the same pdev > are attached to a single guest and then bound to a single process > (thus same PASID) within that guest, we cannot easily support this case > by refcounting the number of users. As there is only one SL page table > per PASID while we have multiple aux domains thus multiple SL page tables > for the same PASID. > > Extra unbinding guest PASID can happen due to race between normal and > exception cases. Termination of one aux domain may affect others unless > we actively track and switch aux domains to ensure the validity of SL > page tables and TLB states in the shared PASID entry. > > Support for sharing second level PGDs across domains can reduce the > complexity but this is not available due to the limitations on VFIO > container architecture. We can revisit this decision once sharing PGDs > are available. > > Overall, the complexity and potential glitch do not warrant this unlikely > use case thereby removed by this patch. > > Cc: Kevin Tian > Cc: Lu Baolu > Signed-off-by: Liu Yi L > Signed-off-by: Jacob Pan Fixes: 56722a4398a30 ("iommu/vt-d: Add bind guest PASID support") Acked-by: Lu Baolu Best regards, baolu > --- > drivers/iommu/intel/svm.c | 22 +++++++++------------- > 1 file changed, 9 insertions(+), 13 deletions(-) > > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c > index 6c87c807a0ab..d386853121a2 100644 > --- a/drivers/iommu/intel/svm.c > +++ b/drivers/iommu/intel/svm.c > @@ -277,20 +277,16 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev, > goto out; > } > > + /* > + * Do not allow multiple bindings of the same device-PASID since > + * there is only one SL page tables per PASID. We may revisit > + * once sharing PGD across domains are supported. > + */ > for_each_svm_dev(sdev, svm, dev) { > - /* > - * For devices with aux domains, we should allow > - * multiple bind calls with the same PASID and pdev. > - */ > - if (iommu_dev_feature_enabled(dev, > - IOMMU_DEV_FEAT_AUX)) { > - sdev->users++; > - } else { > - dev_warn_ratelimited(dev, > - "Already bound with PASID %u\n", > - svm->pasid); > - ret = -EBUSY; > - } > + dev_warn_ratelimited(dev, > + "Already bound with PASID %u\n", > + svm->pasid); > + ret = -EBUSY; > goto out; > } > } else { > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu