From patchwork Tue Jan 4 01:56:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolu Lu X-Patchwork-Id: 12702903 X-Patchwork-Delegate: bhelgaas@google.com 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 313FAC433EF for ; Tue, 4 Jan 2022 01:57:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231996AbiADB5n (ORCPT ); Mon, 3 Jan 2022 20:57:43 -0500 Received: from mga03.intel.com ([134.134.136.65]:12185 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232004AbiADB5n (ORCPT ); Mon, 3 Jan 2022 20:57:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1641261463; x=1672797463; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=BdAqjo+MUSj6Xh3VER3Jc4G4M5Gdoc6ONt96ZGjvuNs=; b=iUytksEc1HrP3GIO1q1AKgcboralhjq1v+81WT0K84OYo9vhJOCvG9Bo T/PoeaChsfX7ZAe6NGam9Udj1On3uHwSr97sXLeyclvOt07BdVJXP+/NV yEs1HXcbWnyCcfc1jhhnc4nLTMMkqsCOz89ub0yg/KIgxazaOpzuKGJLt z1v06+4lQTronfpS4zBZRocHKnU3/A50pIpBmp3TYSvWMLORze8iBC5BN 3MnHekGwAjQq1oOL9EKpwHn+yqeRnhIW9r8WyQ2HV7rlIvnw9tLINNlg7 rU6emseLjJje7xayZWdXYc/qS1NTyoLsBTYdF5ZPTVYUS0OrDsxKTPDFo g==; X-IronPort-AV: E=McAfee;i="6200,9189,10216"; a="242095810" X-IronPort-AV: E=Sophos;i="5.88,258,1635231600"; d="scan'208";a="242095810" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jan 2022 17:57:43 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,258,1635231600"; d="scan'208";a="667573208" Received: from allen-box.sh.intel.com ([10.239.159.118]) by fmsmga001.fm.intel.com with ESMTP; 03 Jan 2022 17:57:36 -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 v5 02/14] driver core: Add dma_cleanup callback in bus_type Date: Tue, 4 Jan 2022 09:56:32 +0800 Message-Id: <20220104015644.2294354-3-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220104015644.2294354-1-baolu.lu@linux.intel.com> References: <20220104015644.2294354-1-baolu.lu@linux.intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@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. Signed-off-by: Lu Baolu Reviewed-by: Greg Kroah-Hartman --- include/linux/device/bus.h | 3 +++ drivers/base/dd.c | 5 +++++ 2 files changed, 8 insertions(+) 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 9eaaff2f556c..2bcbd358eda3 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -662,6 +662,8 @@ 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); @@ -1205,6 +1207,9 @@ 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);