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 9804DC433EF for ; Mon, 6 Dec 2021 01:59:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232110AbhLFCDG (ORCPT ); Sun, 5 Dec 2021 21:03:06 -0500 Received: from mga12.intel.com ([192.55.52.136]:1386 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231851AbhLFCDF (ORCPT ); Sun, 5 Dec 2021 21:03:05 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10189"; a="217255471" X-IronPort-AV: E=Sophos;i="5.87,290,1631602800"; d="scan'208";a="217255471" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Dec 2021 17:59:37 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.87,290,1631602800"; d="scan'208";a="514541949" Received: from allen-box.sh.intel.com ([10.239.159.118]) by orsmga008.jf.intel.com with ESMTP; 05 Dec 2021 17:59:26 -0800 From: Lu Baolu To: Greg Kroah-Hartman , Joerg Roedel , Alex Williamson , Bjorn Helgaas , Jason Gunthorpe , Christoph Hellwig , Kevin Tian , Ashok Raj Cc: Will Deacon , Robin Murphy , Dan Williams , rafael@kernel.org, Diana Craciun , Cornelia Huck , Eric Auger , Liu Yi L , Jacob jun Pan , Chaitanya Kulkarni , Stuart Yoder , Laurentiu Tudor , Thierry Reding , David Airlie , Daniel Vetter , Jonathan Hunter , Li Yang , Dmitry Osipenko , iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Lu Baolu Subject: [PATCH v3 02/18] driver core: Add dma_cleanup callback in bus_type Date: Mon, 6 Dec 2021 09:58:47 +0800 Message-Id: <20211206015903.88687-3-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211206015903.88687-1-baolu.lu@linux.intel.com> References: <20211206015903.88687-1-baolu.lu@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The bus_type structure defines dma_configure() callback for bus drivers to configure DMA on the devices. This adds the paired dma_cleanup() callback and calls it during driver unbinding so that bus drivers can do some cleanup work. One use case for this paired DMA callbacks is for the bus driver to check for DMA ownership conflicts during driver binding, where multiple devices belonging to a same IOMMU group (the minimum granularity of isolation and protection) may be assigned to kernel drivers or user space respectively. Without this change, for example, the vfio driver has to listen to a bus BOUND_DRIVER event and then BUG_ON() in case of dma ownership conflict. This leads to bad user experience since careless driver binding operation may crash the system if the admin overlooks the group restriction. Aside from bad design, this leads to a security problem as a root user, even with lockdown=integrity, can force the kernel to BUG. With this change, the bus driver could check and set the DMA ownership in driver binding process and fail on ownership conflicts. The DMA ownership should be released during driver unbinding. Suggested-by: Jason Gunthorpe Link: https://lore.kernel.org/linux-iommu/20210922123931.GI327412@nvidia.com/ Link: https://lore.kernel.org/linux-iommu/20210928115751.GK964074@nvidia.com/ Signed-off-by: Lu Baolu --- include/linux/device/bus.h | 3 +++ drivers/base/dd.c | 7 ++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/include/linux/device/bus.h b/include/linux/device/bus.h index a039ab809753..d8b29ccd07e5 100644 --- a/include/linux/device/bus.h +++ b/include/linux/device/bus.h @@ -59,6 +59,8 @@ struct fwnode_handle; * bus supports. * @dma_configure: Called to setup DMA configuration on a device on * this bus. + * @dma_cleanup: Called to cleanup DMA configuration on a device on + * this bus. * @pm: Power management operations of this bus, callback the specific * device driver's pm-ops. * @iommu_ops: IOMMU specific operations for this bus, used to attach IOMMU @@ -103,6 +105,7 @@ struct bus_type { int (*num_vf)(struct device *dev); int (*dma_configure)(struct device *dev); + void (*dma_cleanup)(struct device *dev); const struct dev_pm_ops *pm; diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 68ea1f949daa..ae457fa2bca6 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -577,7 +577,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) if (dev->bus->dma_configure) { ret = dev->bus->dma_configure(dev); if (ret) - goto probe_failed; + goto pinctrl_bind_failed; } ret = driver_sysfs_add(dev); @@ -660,6 +660,8 @@ static int really_probe(struct device *dev, struct device_driver *drv) if (dev->bus) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_DRIVER_NOT_BOUND, dev); + if (dev->bus->dma_cleanup) + dev->bus->dma_cleanup(dev); pinctrl_bind_failed: device_links_no_driver(dev); devres_release_all(dev); @@ -1204,6 +1206,9 @@ static void __device_release_driver(struct device *dev, struct device *parent) else if (drv->remove) drv->remove(dev); + if (dev->bus->dma_cleanup) + dev->bus->dma_cleanup(dev); + device_links_driver_cleanup(dev); devres_release_all(dev); -- 2.25.1