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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BF10C433EF for ; Fri, 29 Apr 2022 06:57:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353068AbiD2HBN (ORCPT ); Fri, 29 Apr 2022 03:01:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33964 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230475AbiD2HBK (ORCPT ); Fri, 29 Apr 2022 03:01:10 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0654BCB54 for ; Thu, 28 Apr 2022 23:57:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1651215473; x=1682751473; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=7IYIalnzyIdxUGK/p8/irKiOiXWCGEyooF3P66WCsLY=; b=E1EaBuSJQjaglLjfptmA3rAdYsHg0Mqf02rYYgA4uoM5xJ1O7JN9KkYB jCI11NtcupgxDj621J/UwsHPjlUAqjX42gHHptkQ1Q47BmV+cQ0ZRMqtR XpG3qdbxINSAHYxMR5hqjsLDDQB93c6449oedd0Qq4dA7d2uPws+oyjfQ J1LPTiDSJGc5Qi0UhN6m+ckQTNgVaOPMwquSOt5fQGzhPlaA7NXaxsXv8 +7G5/FodCelDpTKQpxQ7NCd+Tvp0OyZzvw7MebyIuR5jbHSSTEUWLm083 YnmFYh3h3oXm7b2na0d2/mFKctf6h3s/PZBG0Sip8EHGZZjTfyqcHOHFA A==; X-IronPort-AV: E=McAfee;i="6400,9594,10331"; a="253938138" X-IronPort-AV: E=Sophos;i="5.91,297,1647327600"; d="scan'208";a="253938138" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2022 23:57:52 -0700 X-IronPort-AV: E=Sophos;i="5.91,297,1647327600"; d="scan'208";a="581937812" Received: from lye4-mobl.ccr.corp.intel.com (HELO [10.249.170.95]) ([10.249.170.95]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2022 23:57:48 -0700 Message-ID: <0e459e6e-f236-7a58-970a-a47677a23b44@linux.intel.com> Date: Fri, 29 Apr 2022 14:57:46 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH v2 03/14] iommu: Move bus setup to IOMMU device registration Content-Language: en-US To: Robin Murphy , joro@8bytes.org, will@kernel.org Cc: iommu@lists.linux-foundation.org, sven@svenpeter.dev, robdclark@gmail.com, m.szyprowski@samsung.com, yong.wu@mediatek.com, mjrosato@linux.ibm.com, gerald.schaefer@linux.ibm.com, zhang.lyra@gmail.com, thierry.reding@gmail.com, vdumpa@nvidia.com, jean-philippe@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <1faba5b5c094379df3d99b8fec924ab50ad75482.1650890638.git.robin.murphy@arm.com> From: Baolu Lu In-Reply-To: <1faba5b5c094379df3d99b8fec924ab50ad75482.1650890638.git.robin.murphy@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Robin, On 2022/4/28 21:18, Robin Murphy wrote: > Move the bus setup to iommu_device_register(). This should allow > bus_iommu_probe() to be correctly replayed for multiple IOMMU instances, > and leaves bus_set_iommu() as a glorified no-op to be cleaned up next. I re-fetched the latest patches on https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus and rolled back the head to "iommu: Cleanup bus_set_iommu". The test machine still hangs during boot. I went through the code. It seems that the .probe_device for Intel IOMMU driver can't handle the probe replay well. It always assumes that the device has never been probed. Best regards, baolu > > At this point we can also handle cleanup better than just rolling back > the most-recently-touched bus upon failure - which may release devices > owned by other already-registered instances, and still leave devices on > other buses with dangling pointers to the failed instance. Now it's easy > to clean up the exact footprint of a given instance, no more, no less. > > Tested-by: Marek Szyprowski > Signed-off-by: Robin Murphy > --- > drivers/iommu/iommu.c | 51 +++++++++++++++++++++++-------------------- > 1 file changed, 27 insertions(+), 24 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 6c4621afc8cf..c89af4dc54c2 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -175,6 +175,14 @@ static int __init iommu_subsys_init(void) > } > subsys_initcall(iommu_subsys_init); > > +static int remove_iommu_group(struct device *dev, void *data) > +{ > + if (dev->iommu && dev->iommu->iommu_dev == data) > + iommu_release_device(dev); > + > + return 0; > +} > + > /** > * iommu_device_register() - Register an IOMMU hardware instance > * @iommu: IOMMU handle for the instance > @@ -197,12 +205,29 @@ int iommu_device_register(struct iommu_device *iommu, > spin_lock(&iommu_device_lock); > list_add_tail(&iommu->list, &iommu_device_list); > spin_unlock(&iommu_device_lock); > + > + for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) { > + struct bus_type *bus = iommu_buses[i]; > + int err; > + > + WARN_ON(bus->iommu_ops && bus->iommu_ops != ops); > + bus->iommu_ops = ops; > + err = bus_iommu_probe(bus); > + if (err) { > + iommu_device_unregister(iommu); > + return err; > + } > + } > + > return 0; > } > EXPORT_SYMBOL_GPL(iommu_device_register); > > void iommu_device_unregister(struct iommu_device *iommu) > { > + for (int i = 0; i < ARRAY_SIZE(iommu_buses); i++) > + bus_for_each_dev(iommu_buses[i], NULL, iommu, remove_iommu_group); > + > spin_lock(&iommu_device_lock); > list_del(&iommu->list); > spin_unlock(&iommu_device_lock); > @@ -1655,13 +1680,6 @@ static int probe_iommu_group(struct device *dev, void *data) > return ret; > } > > -static int remove_iommu_group(struct device *dev, void *data) > -{ > - iommu_release_device(dev); > - > - return 0; > -} > - > static int iommu_bus_notifier(struct notifier_block *nb, > unsigned long action, void *data) > { > @@ -1884,27 +1902,12 @@ static int iommu_bus_init(struct bus_type *bus) > */ > int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops) > { > - int err; > - > - if (ops == NULL) { > - bus->iommu_ops = NULL; > - return 0; > - } > - > - if (bus->iommu_ops != NULL) > + if (bus->iommu_ops && ops && bus->iommu_ops != ops) > return -EBUSY; > > bus->iommu_ops = ops; > > - /* Do IOMMU specific setup for this bus-type */ > - err = bus_iommu_probe(bus); > - if (err) { > - /* Clean up */ > - bus_for_each_dev(bus, NULL, NULL, remove_iommu_group); > - bus->iommu_ops = NULL; > - } > - > - return err; > + return 0; > } > EXPORT_SYMBOL_GPL(bus_set_iommu); >