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=-9.3 required=3.0 tests=DATE_IN_PAST_24_48, 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 F39DEC43140 for ; Fri, 6 Sep 2019 08:17:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DED482081B for ; Fri, 6 Sep 2019 08:17:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392613AbfIFIRq (ORCPT ); Fri, 6 Sep 2019 04:17:46 -0400 Received: from mga11.intel.com ([192.55.52.93]:23720 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391410AbfIFIRn (ORCPT ); Fri, 6 Sep 2019 04:17:43 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Sep 2019 01:17:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,472,1559545200"; d="scan'208";a="383186173" Received: from yiliu-dev.bj.intel.com ([10.238.156.139]) by fmsmga005.fm.intel.com with ESMTP; 06 Sep 2019 01:17:40 -0700 From: Liu Yi L To: alex.williamson@redhat.com, kwankhede@nvidia.com Cc: kevin.tian@intel.com, baolu.lu@linux.intel.com, yi.l.liu@intel.com, yi.y.sun@intel.com, joro@8bytes.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, yan.y.zhao@intel.com, shaopeng.he@intel.com, chenbo.xia@intel.com, jun.j.tian@intel.com Subject: [PATCH v2 08/13] vfio/pci: protect cap/ecap_perm bits alloc/free with atomic op Date: Thu, 5 Sep 2019 15:59:25 +0800 Message-Id: <1567670370-4484-9-git-send-email-yi.l.liu@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1567670370-4484-1-git-send-email-yi.l.liu@intel.com> References: <1567670370-4484-1-git-send-email-yi.l.liu@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 f0891bd..1b3e6e5 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -992,11 +992,17 @@ 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]); @@ -1013,6 +1019,9 @@ 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