From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Liu, Yi L" Subject: [RFC v3 2/3] vfio/pci: protect cap/ecap_perm bits alloc/free with atomic op Date: Tue, 23 Apr 2019 20:14:39 +0800 Message-ID: <1556021680-2911-3-git-send-email-yi.l.liu@intel.com> References: <1556021680-2911-1-git-send-email-yi.l.liu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1556021680-2911-1-git-send-email-yi.l.liu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, kwankhede-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org Cc: kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Liu-i9wRM+HIrmnmtl4Z8vJ8Kg761KYD1DLY@public.gmane.org, jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yamada.masahiro-uWyLwvC0a2jby3iVrkZq2A@public.gmane.org, yi.y.sun-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: iommu@lists.linux-foundation.org There is a case in which cap_perms and ecap_perms can be reallocated by different modules. e.g. the vfio-mdev-pci sample driver. To secure the initialization of cap_perms and ecap_perms, this patch adds an atomic variable to track the user of cap/ecap_perms bits. First caller of vfio_pci_init_perm_bits() will initialize the bits. While the last caller of vfio_pci_uninit_perm_bits() will free the bits. Cc: Kevin Tian Cc: Lu Baolu Suggested-by: Alex Williamson Signed-off-by: Liu, Yi L --- drivers/vfio/pci/vfio_pci_config.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index e82b511..913fca6 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -996,11 +996,17 @@ static int __init init_pci_ext_cap_pwr_perm(struct perm_bits *perm) return 0; } +/* Track the user number of the cap/ecap perm_bits */ +atomic_t vfio_pci_perm_bits_users = ATOMIC_INIT(0); + /* * Initialize the shared permission tables */ void vfio_pci_uninit_perm_bits(void) { + if (atomic_dec_return(&vfio_pci_perm_bits_users)) + return; + free_perm_bits(&cap_perms[PCI_CAP_ID_BASIC]); free_perm_bits(&cap_perms[PCI_CAP_ID_PM]); @@ -1017,6 +1023,9 @@ int __init vfio_pci_init_perm_bits(void) { int ret; + if (atomic_inc_return(&vfio_pci_perm_bits_users) != 1) + return 0; + /* Basic config space */ ret = init_pci_cap_basic_perm(&cap_perms[PCI_CAP_ID_BASIC]); -- 2.7.4 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=DATE_IN_PAST_24_48, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 BE15DC282E1 for ; Wed, 24 Apr 2019 12:31:04 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 944A820811 for ; Wed, 24 Apr 2019 12:31:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 944A820811 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 7BB01FD8; Wed, 24 Apr 2019 12:31:04 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 393C6FCF for ; Wed, 24 Apr 2019 12:31:03 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B298A82B for ; Wed, 24 Apr 2019 12:31:02 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 Apr 2019 05:31:02 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,389,1549958400"; d="scan'208";a="167475678" Received: from yiliu-dev.bj.intel.com ([10.238.156.125]) by fmsmga001.fm.intel.com with ESMTP; 24 Apr 2019 05:30:59 -0700 From: "Liu, Yi L" To: alex.williamson@redhat.com, kwankhede@nvidia.com Subject: [RFC v3 2/3] vfio/pci: protect cap/ecap_perm bits alloc/free with atomic op Date: Tue, 23 Apr 2019 20:14:39 +0800 Message-Id: <1556021680-2911-3-git-send-email-yi.l.liu@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1556021680-2911-1-git-send-email-yi.l.liu@intel.com> References: <1556021680-2911-1-git-send-email-yi.l.liu@intel.com> Cc: kevin.tian@intel.com, kvm@vger.kernel.org, Liu@mail.linuxfoundation.org, jean-philippe.brucker@arm.com, linux-kernel@vger.kernel.org, yamada.masahiro@socionext.com, yi.y.sun@intel.com, iommu@lists.linux-foundation.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Message-ID: <20190423121439.rsCelFI6Gz2cQcMvqmFlncmlURLVBDq5OBYF4oG4gP4@z> There is a case in which cap_perms and ecap_perms can be reallocated by different modules. e.g. the vfio-mdev-pci sample driver. To secure the initialization of cap_perms and ecap_perms, this patch adds an atomic variable to track the user of cap/ecap_perms bits. First caller of vfio_pci_init_perm_bits() will initialize the bits. While the last caller of vfio_pci_uninit_perm_bits() will free the bits. Cc: Kevin Tian Cc: Lu Baolu Suggested-by: Alex Williamson Signed-off-by: Liu, Yi L --- drivers/vfio/pci/vfio_pci_config.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index e82b511..913fca6 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -996,11 +996,17 @@ static int __init init_pci_ext_cap_pwr_perm(struct perm_bits *perm) return 0; } +/* Track the user number of the cap/ecap perm_bits */ +atomic_t vfio_pci_perm_bits_users = ATOMIC_INIT(0); + /* * Initialize the shared permission tables */ void vfio_pci_uninit_perm_bits(void) { + if (atomic_dec_return(&vfio_pci_perm_bits_users)) + return; + free_perm_bits(&cap_perms[PCI_CAP_ID_BASIC]); free_perm_bits(&cap_perms[PCI_CAP_ID_PM]); @@ -1017,6 +1023,9 @@ int __init vfio_pci_init_perm_bits(void) { int ret; + if (atomic_inc_return(&vfio_pci_perm_bits_users) != 1) + return 0; + /* Basic config space */ ret = init_pci_cap_basic_perm(&cap_perms[PCI_CAP_ID_BASIC]); -- 2.7.4 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu