From patchwork Tue Dec 22 15:43:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11986987 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 8384BC433E0 for ; Tue, 22 Dec 2020 15:43:57 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 3DC2B23105 for ; Tue, 22 Dec 2020 15:43:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3DC2B23105 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.57961.101650 (Exim 4.92) (envelope-from ) id 1krjpB-0006cn-S3; Tue, 22 Dec 2020 15:43:45 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 57961.101650; Tue, 22 Dec 2020 15:43:45 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1krjpB-0006cg-O5; Tue, 22 Dec 2020 15:43:45 +0000 Received: by outflank-mailman (input) for mailman id 57961; Tue, 22 Dec 2020 15:43:44 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1krjpA-0006ab-72 for xen-devel@lists.xenproject.org; Tue, 22 Dec 2020 15:43:44 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1krjp9-0001pp-Qe; Tue, 22 Dec 2020 15:43:43 +0000 Received: from 54-240-197-235.amazon.com ([54.240.197.235] helo=ufe34d9ed68d054.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1krjp9-0002Vd-H1; Tue, 22 Dec 2020 15:43:43 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From; bh=oGKgq5COKIk8NxpKicCWyg/HHbH44EXhBG+TPo1gMSg=; b=6F1sIpK8zXz525iNpH+YZy4J3 7CHZgeRZybwOTkVZ61q5urpWMtfSXXpDnObgRW2hK+49+shv6uDJaRniyyRhf4yEUuRbZPWTVdrkD ZhrkwGNjSSbPUCzDwM4+4E6fhZ46DK1HNbyal5aytfHiXgVlbyIiiuGJC0FrLuObJsjOw=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: hongyxia@amazon.co.uk, Julien Grall , Jan Beulich , Paul Durrant Subject: [PATCH for-4.15 2/4] xen/iommu: x86: Free the IOMMU page-tables with the pgtables.lock held Date: Tue, 22 Dec 2020 15:43:36 +0000 Message-Id: <20201222154338.9459-3-julien@xen.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201222154338.9459-1-julien@xen.org> References: <20201222154338.9459-1-julien@xen.org> From: Julien Grall The pgtables.lock is protecting access to the page list pgtables.list. However, iommu_free_pgtables() will not held it. I guess it was assumed that page-tables cannot be allocated while the domain is dying. Unfortunately, there is no guarantee that iommu_map() will not be called while a domain is dying (it looks like to be possible from XEN_DOMCTL_memory_mapping). So it would be possible to be concurrently allocate memory and free the page-tables. Therefore, we need to held the lock when freeing the page tables. There are more issues around the IOMMU page-allocator. They will be handled in follow-up patches. Signed-off-by: Julien Grall --- xen/drivers/passthrough/x86/iommu.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/xen/drivers/passthrough/x86/iommu.c b/xen/drivers/passthrough/x86/iommu.c index cea1032b3d02..779dbb5b98ba 100644 --- a/xen/drivers/passthrough/x86/iommu.c +++ b/xen/drivers/passthrough/x86/iommu.c @@ -267,13 +267,18 @@ int iommu_free_pgtables(struct domain *d) struct page_info *pg; unsigned int done = 0; + spin_lock(&hd->arch.pgtables.lock); while ( (pg = page_list_remove_head(&hd->arch.pgtables.list)) ) { free_domheap_page(pg); if ( !(++done & 0xff) && general_preempt_check() ) + { + spin_unlock(&hd->arch.pgtables.lock); return -ERESTART; + } } + spin_unlock(&hd->arch.pgtables.lock); return 0; }