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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 9F215C5DF60 for ; Fri, 8 Nov 2019 03:09:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 70BAE222CB for ; Fri, 8 Nov 2019 03:09:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727102AbfKHDJA (ORCPT ); Thu, 7 Nov 2019 22:09:00 -0500 Received: from mga18.intel.com ([134.134.136.126]:23723 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725930AbfKHDJA (ORCPT ); Thu, 7 Nov 2019 22:09:00 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Nov 2019 19:09:00 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,280,1569308400"; d="scan'208";a="228055533" Received: from allen-box.sh.intel.com (HELO [10.239.159.136]) ([10.239.159.136]) by fmsmga004.fm.intel.com with ESMTP; 07 Nov 2019 19:08:58 -0800 Cc: baolu.lu@linux.intel.com, iommu@lists.linux-foundation.org, dwmw2@infradead.org Subject: Re: [PATCH] intel-iommu: Turn off translations at shutdown To: Deepa Dinamani , joro@8bytes.org, linux-kernel@vger.kernel.org References: <20191107205914.10611-1-deepa.kernel@gmail.com> From: Lu Baolu Message-ID: Date: Fri, 8 Nov 2019 11:06:08 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191107205914.10611-1-deepa.kernel@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 11/8/19 4:59 AM, Deepa Dinamani wrote: > The intel-iommu driver assumes that the iommu state is > cleaned up at the start of the new kernel. > But, when we try to kexec boot something other than the > Linux kernel, the cleanup cannot be relied upon. > Hence, cleanup before we go down for reboot. > > Keeping the cleanup at initialization also, in case BIOS > leaves the IOMMU enabled. > > I considered turning off iommu only during kexec reboot, > but a clean shutdown seems always a good idea. But if > someone wants to make it conditional, we can do that. > > Tested that before, the info message > 'DMAR: Translation was enabled for but we are not in kdump mode' > would be reported for each iommu. The message will not appear when the > DMA-remapping is not enabled on entry to the kernel. > > Signed-off-by: Deepa Dinamani > --- > drivers/iommu/intel-iommu.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index fe8097078669..f0636b263722 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -4764,6 +4764,26 @@ static void intel_disable_iommus(void) > iommu_disable_translation(iommu); > } > > +static void intel_iommu_shutdown(void) > +{ > + struct dmar_drhd_unit *drhd; > + struct intel_iommu *iommu = NULL; > + > + if (no_iommu || dmar_disabled) > + return; > + > + down_write(&dmar_global_lock); > + > + /* Disable PMRs explicitly here. */ > + for_each_iommu(iommu, drhd) > + iommu_disable_protect_mem_regions(iommu); > + > + /* Make sure the IOMMUs are switched off */ > + intel_disable_iommus(); > + > + up_write(&dmar_global_lock); > +} > + > static inline struct intel_iommu *dev_to_intel_iommu(struct device *dev) > { > struct iommu_device *iommu_dev = dev_to_iommu_device(dev); > @@ -5013,6 +5033,8 @@ int __init intel_iommu_init(void) > } > up_write(&dmar_global_lock); > > + x86_platform.iommu_shutdown = intel_iommu_shutdown; How about moving it to detect_intel_iommu() in drivers/iommu/dmar.c? And make sure that it's included with CONFIG_X86_64. Best regards, baolu > + > #if defined(CONFIG_X86) && defined(CONFIG_SWIOTLB) > /* > * If the system has no untrusted device or the user has decided >