Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752987AbdC2Pun (ORCPT ); Wed, 29 Mar 2017 11:50:43 -0400 Received: from mga09.intel.com ([134.134.136.24]:34889 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752238AbdC2Pul (ORCPT ); Wed, 29 Mar 2017 11:50:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.36,241,1486454400"; d="scan'208";a="949443087" Date: Wed, 29 Mar 2017 08:51:53 -0700 From: Jacob Pan To: Joerg Roedel Cc: iommu@lists.linux-foundation.org, Joerg Roedel , David Woodhouse , linux-kernel@vger.kernel.org, jacob.jun.pan@linux.intel.com Subject: Re: [PATCH] iommu/vt-d: Make sure IOMMUs are off when intel_iommu=off Message-ID: <20170329085153.5d215d44@jacob-builder> In-Reply-To: <1490799639-15965-1-git-send-email-joro@8bytes.org> References: <1490799639-15965-1-git-send-email-joro@8bytes.org> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1804 Lines: 62 On Wed, 29 Mar 2017 17:00:39 +0200 Joerg Roedel wrote: > From: Joerg Roedel > > When booting into a kexec kernel with intel_iommu=off, and > the previous kernel had intel_iommu=on, the IOMMU hardware > is still enabled and gets not disabled by the new kernel. > > This causes the boot to fail because DMA is blocked by the > hardware. Disable the IOMMUs when we find it enabled in the > kexec kernel and boot with intel_iommu=off. > > Signed-off-by: Joerg Roedel > --- > drivers/iommu/intel-iommu.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index d412a31..1662288 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -4730,6 +4730,15 @@ static int intel_iommu_cpu_dead(unsigned int > cpu) return 0; > } > > +static void intel_disable_iommus(void) > +{ > + struct intel_iommu *iommu = NULL; > + struct dmar_drhd_unit *drhd; > + > + for_each_iommu(iommu, drhd) > + iommu_disable_translation(iommu); should we also disable IR here? i.e. iommu_disable_irq_remapping(iommu); > +} > + > static inline struct intel_iommu *dev_to_intel_iommu(struct device > *dev) { > return container_of(dev, struct intel_iommu, iommu.dev); > @@ -4840,8 +4849,15 @@ int __init intel_iommu_init(void) > goto out_free_dmar; > } > > - if (no_iommu || dmar_disabled) > + if (no_iommu || dmar_disabled) { > + /* > + * Make sure the IOMMUs are switched off, even when > we > + * boot into a kexec kernel and the previous kernel > left > + * them enabled > + */ > + intel_disable_iommus(); > goto out_free_dmar; > + } > > if (list_empty(&dmar_rmrr_units)) > pr_info("No RMRR found\n"); [Jacob Pan]