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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 4C3A6C433E1 for ; Thu, 27 Aug 2020 04:32:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 24BEE20786 for ; Thu, 27 Aug 2020 04:32:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726344AbgH0EcV (ORCPT ); Thu, 27 Aug 2020 00:32:21 -0400 Received: from mga03.intel.com ([134.134.136.65]:39650 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726028AbgH0EcU (ORCPT ); Thu, 27 Aug 2020 00:32:20 -0400 IronPort-SDR: iA5SXB7GGQjjn61IQRamQIePuDNQKpokkv3ESiHZB8N1IQc9fSp87TqyAxHk2fSISbvBO+g7LB z9uLVIsQnFaA== X-IronPort-AV: E=McAfee;i="6000,8403,9725"; a="156425098" X-IronPort-AV: E=Sophos;i="5.76,358,1592895600"; d="scan'208";a="156425098" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Aug 2020 21:32:20 -0700 IronPort-SDR: KE9+dvvSE3l0GaVQ1uneodXF+TsriwcFAsQliiYinM7BFemm5QZFqtklAwNtuvnUwq+kIrwVgt ZjhTSXfxtOpg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,358,1592895600"; d="scan'208";a="403287355" Received: from allen-box.sh.intel.com ([10.239.159.139]) by fmsmga001.fm.intel.com with ESMTP; 26 Aug 2020 21:32:18 -0700 From: Lu Baolu To: Joerg Roedel Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Lu Baolu , Andy Lutomirski , Jacob Pan , Kevin Tian , Ashok Raj Subject: [PATCH v2 1/1] iommu/vt-d: Serialize IOMMU GCMD register modifications Date: Thu, 27 Aug 2020 12:25:13 +0800 Message-Id: <20200827042513.30292-1-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The VT-d spec requires (10.4.4 Global Command Register, GCMD_REG General Description) that: If multiple control fields in this register need to be modified, software must serialize the modifications through multiple writes to this register. However, in irq_remapping.c, modifications of IRE and CFI are done in one write. We need to do two separate writes with STS checking after each. Fixes: af8d102f999a4 ("x86/intel/irq_remapping: Clean up x2apic opt-out security warning mess") Cc: Andy Lutomirski Cc: Jacob Pan Cc: Kevin Tian Cc: Ashok Raj Signed-off-by: Lu Baolu --- drivers/iommu/intel/irq_remapping.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) Change log: v1->v2: - v1 posted here https://lore.kernel.org/linux-iommu/20200826025825.2322-1-baolu.lu@linux.intel.com/; - Add status check before disabling CFI. (Kevin) diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c index 9564d23d094f..7552bb7e92c8 100644 --- a/drivers/iommu/intel/irq_remapping.c +++ b/drivers/iommu/intel/irq_remapping.c @@ -507,12 +507,19 @@ static void iommu_enable_irq_remapping(struct intel_iommu *iommu) /* Enable interrupt-remapping */ iommu->gcmd |= DMA_GCMD_IRE; - iommu->gcmd &= ~DMA_GCMD_CFI; /* Block compatibility-format MSIs */ writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG); - IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG, readl, (sts & DMA_GSTS_IRES), sts); + /* Block compatibility-format MSIs */ + sts = readl(iommu->reg + DMAR_GSTS_REG); + if (sts & DMA_GSTS_CFIS) { + iommu->gcmd &= ~DMA_GCMD_CFI; + writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG); + IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG, + readl, !(sts & DMA_GSTS_CFIS), sts); + } + /* * With CFI clear in the Global Command register, we should be * protected from dangerous (i.e. compatibility) interrupts -- 2.17.1