Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932203Ab1EQTlW (ORCPT ); Tue, 17 May 2011 15:41:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35701 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932087Ab1EQTlS (ORCPT ); Tue, 17 May 2011 15:41:18 -0400 Subject: Re: [PATCH] pci, dmar: flush IOTLB before exit domain From: Alex Williamson To: David Woodhouse Cc: Yinghai Lu , Kalle Valo , "linux-pci@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , Jesse Barnes In-Reply-To: <1305558798.3146.48.camel@x201> References: <4DC34B21.9040203@oracle.com> <1304952530.30435.16.camel@i7.infradead.org> <1305558798.3146.48.camel@x201> Content-Type: text/plain; charset="UTF-8" Date: Tue, 17 May 2011 13:41:02 -0600 Message-ID: <1305661262.29268.27.camel@x201> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2363 Lines: 62 On Mon, 2011-05-16 at 09:13 -0600, Alex Williamson wrote: > On Mon, 2011-05-09 at 15:48 +0100, David Woodhouse wrote: > > On Thu, 2011-05-05 at 18:13 -0700, Yinghai Lu wrote: > > > @@ -3252,6 +3252,9 @@ static int device_notifier(struct notifi > > > return 0; > > > > > > if (action == BUS_NOTIFY_UNBOUND_DRIVER && !iommu_pass_through) { > > > + /* before we remove dev with domain, flush IOTLB */ > > > + flush_unmaps(); > > > + > > > domain_remove_one_dev_info(domain, pdev); > > > > > > if (!(domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) && > > > > That calls flush_unmaps() without the async_umap_flush_lock held, > > doesn't it? A few days ago I asked someone else to test this candidate > > patch for a similar issue: > > > > http://david.woodhou.se/flush-unmaps-on-unbind.patch > > Copying here: > > > diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c > > index d552d2c..7e606d6 100644 > > --- a/drivers/pci/intel-iommu.c > > +++ b/drivers/pci/intel-iommu.c > > @@ -3256,8 +3259,10 @@ static int device_notifier(struct notifier_block *nb, > > > > if (!(domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE) && > > !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY) && > > - list_empty(&domain->devices)) > > + list_empty(&domain->devices)) { > > + flush_unmaps_timeout(0); > > domain_exit(domain); > > + } > > } > > > > return 0; > > @@ -3587,6 +3592,7 @@ static void intel_iommu_domain_destroy(struct iommu_domain *domain) > > struct dmar_domain *dmar_domain = domain->priv; > > > > domain->priv = NULL; > > + flush_unmaps_timeout(0); > > vm_domain_exit(dmar_domain); > > } > > David, would it be worthwhile to push the unmaps into the > {vm_}domain_exit() functions to avoid races like this in the future? I > can verify the above resolves a panic after unbinding a device from > snd_hda_intel that I hit recently. Do you plan to push this for .39? BTW, is this second chunk really needed? VM iommu mappings don't seem to use the lazy unmap path. Thanks, Alex -- 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/