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=-10.0 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_GIT 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 8DC2CC433E0 for ; Tue, 30 Jun 2020 21:01:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 732212074D for ; Tue, 30 Jun 2020 21:01:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727846AbgF3VBJ (ORCPT ); Tue, 30 Jun 2020 17:01:09 -0400 Received: from mga09.intel.com ([134.134.136.24]:26203 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726997AbgF3VBG (ORCPT ); Tue, 30 Jun 2020 17:01:06 -0400 IronPort-SDR: sEpKqU0EMBjDgNWsTZhIxpsgnA2bqa8W0/jMqfo1jbdEMNcu9RBnqFl9rZYMU0g+ewQgkqpZ7P UMvNNCahD0bQ== X-IronPort-AV: E=McAfee;i="6000,8403,9668"; a="147935011" X-IronPort-AV: E=Sophos;i="5.75,298,1589266800"; d="scan'208";a="147935011" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jun 2020 14:01:05 -0700 IronPort-SDR: /wmag5B4Ql9P15sI9srtqyRDa0eh7ubLTsJmfUYXd82SUf6Tho+/plx1WvmKmMlYKGjq3oA2u7 sxgXik/19Wag== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,298,1589266800"; d="scan'208";a="425337243" Received: from jacob-builder.jf.intel.com ([10.7.199.155]) by orsmga004.jf.intel.com with ESMTP; 30 Jun 2020 14:01:05 -0700 From: Jacob Pan To: iommu@lists.linux-foundation.org, LKML , "Lu Baolu" , Joerg Roedel , David Woodhouse Cc: Yi Liu , "Tian, Kevin" , Raj Ashok , Eric Auger , Jacob Pan Subject: [PATCH v2 7/7] iommu/vt-d: Disable multiple GPASID-dev bind Date: Tue, 30 Jun 2020 14:07:38 -0700 Message-Id: <1593551258-39854-8-git-send-email-jacob.jun.pan@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1593551258-39854-1-git-send-email-jacob.jun.pan@linux.intel.com> References: <1593551258-39854-1-git-send-email-jacob.jun.pan@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Fixes: 56722a4398a30 ("iommu/vt-d: Add bind guest PASID support") Acked-by: Lu Baolu Cc: Kevin Tian Cc: Lu Baolu Signed-off-by: Liu Yi L Signed-off-by: Jacob Pan --- 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 { -- 2.7.4