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[2620:137:e000::3:1]) by mx.google.com with ESMTPS id bu23-20020a632957000000b00578b9757214si1095858pgb.163.2023.10.11.20.02.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Oct 2023 20:02:26 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) client-ip=2620:137:e000::3:1; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=AVKX+sBs; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:1 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by morse.vger.email (Postfix) with ESMTP id 83B7880644DD; Wed, 11 Oct 2023 20:02:23 -0700 (PDT) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.10 at morse.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347069AbjJLDBz (ORCPT + 18 others); Wed, 11 Oct 2023 23:01:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235244AbjJLDBn (ORCPT ); Wed, 11 Oct 2023 23:01:43 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E783C0 for ; Wed, 11 Oct 2023 20:01:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1697079694; x=1728615694; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=kkKH+uTlnhRFeXQlDjPdyXZlJ+N82DJ6HJj2xSwbyGk=; b=AVKX+sBscugGjkTGL8SsX6GXVSkGMzqAKoAcTFNVQajY0kAp3NzfcsVb a1I2RMV4/TUC7FtC4bXJK434O52h4OZR0BydozMiB/DL174Pp+e5yGlQ7 WZPjbSQcZFk2WmR4a9sQQIXyvx//Wi9jvdlw3ETTyiFj1oZX9IJ8scU+E SFgkHA2R80c6Kt6Da558/fyjdWI7rG3VQ/Q6v13s27tpxkJz0eonq4EKJ Xl7FONUB5bSu1mbJp0hGBlSEoF9cfP62Kh8VtfqUqm9pyEZIezs1iKPhN nLBwmCE1HCiYszMVABJnnOQAg/0TBmBqyR3s8wdhw43g/jYH9S3lHeNzT g==; X-IronPort-AV: E=McAfee;i="6600,9927,10860"; a="6371527" X-IronPort-AV: E=Sophos;i="6.03,217,1694761200"; d="scan'208";a="6371527" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Oct 2023 20:01:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10860"; a="730736536" X-IronPort-AV: E=Sophos;i="6.03,217,1694761200"; d="scan'208";a="730736536" Received: from sqa-gate.sh.intel.com (HELO spr-2s5.tsp.org) ([10.239.48.212]) by orsmga006.jf.intel.com with ESMTP; 11 Oct 2023 20:01:31 -0700 From: Tina Zhang To: Jason Gunthorpe , Kevin Tian , Lu Baolu Cc: Michael Shavit , Vasant Hegde , "Nicolin Chen ^C-cc=iommu @ lists . linux . dev" , linux-kernel@vger.kernel.org, Tina Zhang , Jason Gunthorpe Subject: [PATCH v7 4/5] iommu: Support mm PASID 1:n with sva domains Date: Thu, 12 Oct 2023 11:01:11 +0800 Message-Id: <20231012030112.82270-5-tina.zhang@intel.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20231012030112.82270-1-tina.zhang@intel.com> References: <20231012030112.82270-1-tina.zhang@intel.com> MIME-Version: 1.0 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on morse.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (morse.vger.email [0.0.0.0]); Wed, 11 Oct 2023 20:02:23 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1779517092192686493 X-GMAIL-MSGID: 1779517092192686493 Each mm bound to devices gets a PASID and corresponding sva domains allocated in iommu_sva_bind_device(), which are referenced by iommu_mm field of the mm. The PASID is released in __mmdrop(), while a sva domain is released when no one is using it (the reference count is decremented in iommu_sva_unbind_device()). However, although sva domains and their PASID are separate objects such that their own life cycles could be handled independently, an enqcmd use case may require releasing the PASID in releasing the mm (i.e., once a PASID is allocated for a mm, it will be permanently used by the mm and won't be released until the end of mm) and only allows to drop the PASID after the sva domains are released. To this end, mmgrab() is called in iommu_sva_domain_alloc() to increment the mm reference count and mmdrop() is invoked in iommu_domain_free() to decrement the mm reference count. Since the required info of PASID and sva domains is kept in struct iommu_mm_data of a mm, use mm->iommu_mm field instead of the old pasid field in mm struct. The sva domain list is protected by iommu_sva_lock. Besides, this patch removes mm_pasid_init(), as with the introduced iommu_mm structure, initializing mm pasid in mm_init() is unnecessary. Reviewed-by: Lu Baolu Reviewed-by: Vasant Hegde Reviewed-by: Jason Gunthorpe Signed-off-by: Tina Zhang --- Change in v7: - Add mm_pasid_init() back and do zeroing mm->iommu_mm pointer in mm_pasid_init() to avoid the use-after-free/double-free problem. Changes in v6: - Rename iommu_sva_alloc_pasid() to iommu_alloc_mm_data(). - Hold the iommu_sva_lock before invoking iommu_alloc_mm_data(). Change in v5: - Use smp_store_release() & READ_ONCE() in storing and loading mm's pasid value. Change in v4: - Rebase to v6.6-rc1. drivers/iommu/iommu-sva.c | 92 +++++++++++++++++++++++---------------- include/linux/iommu.h | 22 ++++++++-- 2 files changed, 73 insertions(+), 41 deletions(-) diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c index 4a2f5699747f..5175e8d85247 100644 --- a/drivers/iommu/iommu-sva.c +++ b/drivers/iommu/iommu-sva.c @@ -12,32 +12,42 @@ static DEFINE_MUTEX(iommu_sva_lock); /* Allocate a PASID for the mm within range (inclusive) */ -static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev) +static struct iommu_mm_data *iommu_alloc_mm_data(struct mm_struct *mm, struct device *dev) { + struct iommu_mm_data *iommu_mm; ioasid_t pasid; - int ret = 0; + + lockdep_assert_held(&iommu_sva_lock); if (!arch_pgtable_dma_compat(mm)) - return -EBUSY; + return ERR_PTR(-EBUSY); - mutex_lock(&iommu_sva_lock); + iommu_mm = mm->iommu_mm; /* Is a PASID already associated with this mm? */ - if (mm_valid_pasid(mm)) { - if (mm->pasid >= dev->iommu->max_pasids) - ret = -EOVERFLOW; - goto out; + if (iommu_mm) { + if (iommu_mm->pasid >= dev->iommu->max_pasids) + return ERR_PTR(-EOVERFLOW); + return iommu_mm; } + iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL); + if (!iommu_mm) + return ERR_PTR(-ENOMEM); + pasid = iommu_alloc_global_pasid(dev); if (pasid == IOMMU_PASID_INVALID) { - ret = -ENOSPC; - goto out; + kfree(iommu_mm); + return ERR_PTR(-ENOSPC); } - mm->pasid = pasid; - ret = 0; -out: - mutex_unlock(&iommu_sva_lock); - return ret; + iommu_mm->pasid = pasid; + INIT_LIST_HEAD(&iommu_mm->sva_domains); + /* + * Make sure the write to mm->iommu_mm is not reordered in front of + * initialization to iommu_mm fields. If it does, readers may see a + * valid iommu_mm with uninitialized values. + */ + smp_store_release(&mm->iommu_mm, iommu_mm); + return iommu_mm; } /** @@ -58,31 +68,33 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev) */ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm) { + struct iommu_mm_data *iommu_mm; struct iommu_domain *domain; struct iommu_sva *handle; int ret; + mutex_lock(&iommu_sva_lock); + /* Allocate mm->pasid if necessary. */ - ret = iommu_sva_alloc_pasid(mm, dev); - if (ret) - return ERR_PTR(ret); + iommu_mm = iommu_alloc_mm_data(mm, dev); + if (IS_ERR(iommu_mm)) { + ret = PTR_ERR(iommu_mm); + goto out_unlock; + } handle = kzalloc(sizeof(*handle), GFP_KERNEL); - if (!handle) - return ERR_PTR(-ENOMEM); - - mutex_lock(&iommu_sva_lock); - /* Search for an existing domain. */ - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid, - IOMMU_DOMAIN_SVA); - if (IS_ERR(domain)) { - ret = PTR_ERR(domain); + if (!handle) { + ret = -ENOMEM; goto out_unlock; } - if (domain) { - domain->users++; - goto out; + /* Search for an existing domain. */ + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) { + ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid); + if (!ret) { + domain->users++; + goto out; + } } /* Allocate a new domain and set it on device pasid. */ @@ -92,23 +104,23 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm goto out_unlock; } - ret = iommu_attach_device_pasid(domain, dev, mm->pasid); + ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid); if (ret) goto out_free_domain; domain->users = 1; + list_add(&domain->next, &mm->iommu_mm->sva_domains); + out: mutex_unlock(&iommu_sva_lock); handle->dev = dev; handle->domain = domain; - return handle; out_free_domain: iommu_domain_free(domain); + kfree(handle); out_unlock: mutex_unlock(&iommu_sva_lock); - kfree(handle); - return ERR_PTR(ret); } EXPORT_SYMBOL_GPL(iommu_sva_bind_device); @@ -124,12 +136,13 @@ EXPORT_SYMBOL_GPL(iommu_sva_bind_device); void iommu_sva_unbind_device(struct iommu_sva *handle) { struct iommu_domain *domain = handle->domain; - ioasid_t pasid = domain->mm->pasid; + struct iommu_mm_data *iommu_mm = domain->mm->iommu_mm; struct device *dev = handle->dev; mutex_lock(&iommu_sva_lock); + iommu_detach_device_pasid(domain, dev, iommu_mm->pasid); if (--domain->users == 0) { - iommu_detach_device_pasid(domain, dev, pasid); + list_del(&domain->next); iommu_domain_free(domain); } mutex_unlock(&iommu_sva_lock); @@ -205,8 +218,11 @@ iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) void mm_pasid_drop(struct mm_struct *mm) { - if (likely(!mm_valid_pasid(mm))) + struct iommu_mm_data *iommu_mm = mm->iommu_mm; + + if (!iommu_mm) return; - iommu_free_global_pasid(mm->pasid); + iommu_free_global_pasid(iommu_mm->pasid); + kfree(iommu_mm); } diff --git a/include/linux/iommu.h b/include/linux/iommu.h index dc1f98e12f4b..cf5ce11fe473 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -109,6 +109,11 @@ struct iommu_domain { struct { /* IOMMU_DOMAIN_SVA */ struct mm_struct *mm; int users; + /* + * Next iommu_domain in mm->iommu_mm->sva-domains list + * protected by iommu_sva_lock. + */ + struct list_head next; }; }; }; @@ -1188,15 +1193,26 @@ static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream #ifdef CONFIG_IOMMU_SVA static inline void mm_pasid_init(struct mm_struct *mm) { - mm->pasid = IOMMU_PASID_INVALID; + /* + * During dup_mm(), a new mm will be memcpy'd from an old one and that makes + * the new mm and the old one point to a same iommu_mm instance. When either + * one of the two mms gets released, the iommu_mm instance is freed, leaving + * the other mm running into a use-after-free/double-free problem. To avoid + * the problem, zeroing the iommu_mm pointer of a new mm is needed here. + */ + mm->iommu_mm = NULL; } static inline bool mm_valid_pasid(struct mm_struct *mm) { - return mm->pasid != IOMMU_PASID_INVALID; + return READ_ONCE(mm->iommu_mm); } static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm) { - return mm->pasid; + struct iommu_mm_data *iommu_mm = READ_ONCE(mm->iommu_mm); + + if (!iommu_mm) + return IOMMU_PASID_INVALID; + return iommu_mm->pasid; } void mm_pasid_drop(struct mm_struct *mm); struct iommu_sva *iommu_sva_bind_device(struct device *dev,