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 7A200C433EF for ; Fri, 18 Feb 2022 00:57:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230325AbiBRA6I (ORCPT ); Thu, 17 Feb 2022 19:58:08 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:36040 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230310AbiBRA6G (ORCPT ); Thu, 17 Feb 2022 19:58:06 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0C9B5EDC9; Thu, 17 Feb 2022 16:57:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1645145870; x=1676681870; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Xumaw0/yMVQuQ10PTWOlc8COKHETP7NDr963ygjrCSw=; b=XdwrD4iA8yClIYVe0XHQT3lnjre4MkZKur/1WECFBSQA4OmalvT/7v+c mT8+WR6toKrSAkG7VrFYR/C4Z/ctLjFGmHz0ca6Xah/VT7HT0krHri01X +O0BOGk+cNAUkBH537i4CMqzMZEdW9gSdS6qtvpWOK75EfNzVzJ2LoM45 xisJAkZJ8G6Ay0/TaubLMjUKOBovYHigU7iifIGtbAkgSoAuGHNP0a8Lv Hx/y/y5+W3NAPDm7oaTKhOVRa6mRa0A4HSpb+ZQXVOYLH2lZ/VNo5V+Gz kOrr/M8Er14hwM+8TRFwfEXd2MbyCPUKXIkVRQRVzmAQgQQPAg8479pRW A==; X-IronPort-AV: E=McAfee;i="6200,9189,10261"; a="275612635" X-IronPort-AV: E=Sophos;i="5.88,377,1635231600"; d="scan'208";a="275612635" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Feb 2022 16:57:09 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,377,1635231600"; d="scan'208";a="637490689" Received: from allen-box.sh.intel.com ([10.239.159.118]) by orsmga004.jf.intel.com with ESMTP; 17 Feb 2022 16:57:01 -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 v6 02/11] driver core: Add dma_cleanup callback in bus_type Date: Fri, 18 Feb 2022 08:55:12 +0800 Message-Id: <20220218005521.172832-3-baolu.lu@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220218005521.172832-1-baolu.lu@linux.intel.com> References: <20220218005521.172832-1-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. 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..de05c5c60c6b 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 && 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 && dev->bus->dma_cleanup) + dev->bus->dma_cleanup(dev); + device_links_driver_cleanup(dev); devres_release_all(dev); -- 2.25.1