Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756389Ab0DBJL0 (ORCPT ); Fri, 2 Apr 2010 05:11:26 -0400 Received: from 8bytes.org ([88.198.83.132]:35890 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753014Ab0DBJLT (ORCPT ); Fri, 2 Apr 2010 05:11:19 -0400 Date: Fri, 2 Apr 2010 11:11:18 +0200 From: Joerg Roedel To: Chris Wright Cc: Joerg Roedel , Neil Horman , Neil Horman , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, hbabu@us.ibm.com, iommu@lists.linux-foundation.org, "Eric W. Biederman" , Vivek Goyal Subject: Re: [PATCH 1/2] x86/amd-iommu: enable iommu before attaching devices Message-ID: <20100402091118.GM24846@8bytes.org> References: <20100331202745.GE13406@hmsreliant.think-freely.org> <20100401142902.GF24846@8bytes.org> <20100401144736.GA14069@shamino.rdu.redhat.com> <20100401155643.GG24846@8bytes.org> <20100401171149.GH13603@shamino.rdu.redhat.com> <20100401201433.GK24846@8bytes.org> <20100402000012.GA8930@hmsreliant.think-freely.org> <20100402003034.GX29241@sequoia.sous-sol.org> <20100402012353.GY29241@sequoia.sous-sol.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100402012353.GY29241@sequoia.sous-sol.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1813 Lines: 51 On Thu, Apr 01, 2010 at 06:23:53PM -0700, Chris Wright wrote: > Hit another kdump problem as reported by Neil Horman. When initializaing > the IOMMU, we attach devices to their domains before the IOMMU is > fully (re)initialized. Attaching a device will issue some important > invalidations. In the context of the newly kexec'd kdump kernel, the > IOMMU may have stale cached data from the original kernel. Because we > do the attach too early, the invalidation commands are placed in the new > command buffer before the IOMMU is updated w/ that buffer. This leaves > the stale entries in the kdump context and can renders device unusable. > Simply enable the IOMMU before we do the attach. > > Cc: Neil Horman > Cc: Vivek Goyal > Signed-off-by: Chris Wright > --- > arch/x86/kernel/amd_iommu_init.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > --- a/arch/x86/kernel/amd_iommu_init.c > +++ b/arch/x86/kernel/amd_iommu_init.c > @@ -1288,6 +1288,8 @@ static int __init amd_iommu_init(void) > if (ret) > goto free; > > + enable_iommus(); > + > if (iommu_pass_through) > ret = amd_iommu_init_passthrough(); > else > @@ -1300,8 +1302,6 @@ static int __init amd_iommu_init(void) > > amd_iommu_init_notifier(); > > - enable_iommus(); > - > if (iommu_pass_through) > goto out; Ok, good to know this fixes the problem. One issue: If the initialization of the domains fails the iommu hardware needs to be disabled again in the free path. Thanks, Joerg -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/