From nobody Sat Apr 11 06:30:50 2026 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 D3230C3F6B0 for ; Mon, 15 Aug 2022 16:20:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232575AbiHOQUu (ORCPT ); Mon, 15 Aug 2022 12:20:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231683AbiHOQUe (ORCPT ); Mon, 15 Aug 2022 12:20:34 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AF91313CFC for ; Mon, 15 Aug 2022 09:20:31 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 15E54113E; Mon, 15 Aug 2022 09:20:32 -0700 (PDT) Received: from e121345-lin.cambridge.arm.com (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D13C83F70D; Mon, 15 Aug 2022 09:20:29 -0700 (PDT) From: Robin Murphy To: joro@8bytes.org Cc: will@kernel.org, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org, baolu.lu@linux.intel.com, kevin.tian@intel.com, suravee.suthikulpanit@amd.com, vasant.hegde@amd.com, mjrosato@linux.ibm.com, schnelle@linux.ibm.com, linux-kernel@vger.kernel.org Subject: [PATCH v4 05/16] iommu: Move bus setup to IOMMU device registration Date: Mon, 15 Aug 2022 17:20:06 +0100 Message-Id: X-Mailer: git-send-email 2.36.1.dirty In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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. 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 Reviewed-By: Krishna Reddy Reviewed-by: Kevin Tian Tested-by: Matthew Rosato # s390 Tested-by: Niklas Schnelle # s390 Signed-off-by: Robin Murphy --- v4: Factor out the ops check in iommu_device_register() to keep the loop even simpler, and comment the nominal change in behaviour drivers/iommu/iommu.c | 55 +++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 25 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index a8d14f2a1035..4db0874a5ed6 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -188,6 +188,14 @@ static int __init iommu_subsys_init(void) } subsys_initcall(iommu_subsys_init); =20 +static int remove_iommu_group(struct device *dev, void *data) +{ + if (dev->iommu && dev->iommu->iommu_dev =3D=3D data) + iommu_release_device(dev); + + return 0; +} + /** * iommu_device_register() - Register an IOMMU hardware instance * @iommu: IOMMU handle for the instance @@ -199,9 +207,18 @@ subsys_initcall(iommu_subsys_init); int iommu_device_register(struct iommu_device *iommu, const struct iommu_ops *ops, struct device *hwdev) { + int err =3D 0; + /* We need to be able to take module references appropriately */ if (WARN_ON(is_module_address((unsigned long)ops) && !ops->owner)) return -EINVAL; + /* + * Temporarily enforce global restriction to a single driver. This was + * already the de-facto behaviour, since any possible combination of + * existing drivers would compete for at least the PCI or platform bus. + */ + if (iommu_buses[0]->iommu_ops && iommu_buses[0]->iommu_ops !=3D ops) + return -EBUSY; =20 iommu->ops =3D ops; if (hwdev) @@ -210,12 +227,22 @@ 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); - return 0; + + for (int i =3D 0; i < ARRAY_SIZE(iommu_buses) && !err; i++) { + iommu_buses[i]->iommu_ops =3D ops; + err =3D bus_iommu_probe(iommu_buses[i]); + } + if (err) + iommu_device_unregister(iommu); + return err; } EXPORT_SYMBOL_GPL(iommu_device_register); =20 void iommu_device_unregister(struct iommu_device *iommu) { + for (int i =3D 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); @@ -1644,13 +1671,6 @@ static int probe_iommu_group(struct device *dev, voi= d *data) return ret; } =20 -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) { @@ -1822,27 +1842,12 @@ int bus_iommu_probe(struct bus_type *bus) */ int bus_set_iommu(struct bus_type *bus, const struct iommu_ops *ops) { - int err; - - if (ops =3D=3D NULL) { - bus->iommu_ops =3D NULL; - return 0; - } - - if (bus->iommu_ops !=3D NULL) + if (bus->iommu_ops && ops && bus->iommu_ops !=3D ops) return -EBUSY; =20 bus->iommu_ops =3D ops; =20 - /* Do IOMMU specific setup for this bus-type */ - err =3D bus_iommu_probe(bus); - if (err) { - /* Clean up */ - bus_for_each_dev(bus, NULL, NULL, remove_iommu_group); - bus->iommu_ops =3D NULL; - } - - return err; + return 0; } EXPORT_SYMBOL_GPL(bus_set_iommu); =20 --=20 2.36.1.dirty