From patchwork Fri Feb 18 00:55:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Baolu Lu X-Patchwork-Id: 12750836 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 C6023C433EF for ; Fri, 18 Feb 2022 00:58:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230384AbiBRA6f (ORCPT ); Thu, 17 Feb 2022 19:58:35 -0500 Received: from gmail-smtp-in.l.google.com ([23.128.96.19]:38064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230366AbiBRA6a (ORCPT ); Thu, 17 Feb 2022 19:58:30 -0500 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8881EAA2E1; Thu, 17 Feb 2022 16:58:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1645145891; x=1676681891; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Z0gFB9jEANNtxw9swDDrsLlWa/7lPuy8uGiGkZnIqZw=; b=Nq8ht0cy5LwzJ3a81fjy+GAhHSmMj9fkC4XSXr7Szj7Xr2oRKdBI+NBc wUzr52g29GfF8TGRYxejQHXOVapFxqkUj9NYmZJv9sX/T6cUoSlfyIS+S SSYenz51/e87vhk1Dqs98l5dd/+dyVY5GCCHBxik4FlJGemV1ZVbMN1N4 u4O0Vojb2a0ZOJ1RtB7rJ7hGFvrX1h9WEArHASzHpHQfYA1UTcC+jPFVo e/uiH++/WvaT/zlUOm5pFFmRx1ibG4L0PMDSSR2CNLHrlFgkwVZzp1Lp6 EPzUrtPRpz1h76lsVQ5MntRcvvY182f2pbmLZ/PMENtndZzSyuwEvC0qQ g==; X-IronPort-AV: E=McAfee;i="6200,9189,10261"; a="248612918" X-IronPort-AV: E=Sophos;i="5.88,377,1635231600"; d="scan'208";a="248612918" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Feb 2022 16:58:00 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,377,1635231600"; d="scan'208";a="637491455" Received: from allen-box.sh.intel.com ([10.239.159.118]) by orsmga004.jf.intel.com with ESMTP; 17 Feb 2022 16:57:52 -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 09/11] vfio: Delete the unbound_list Date: Fri, 18 Feb 2022 08:55:19 +0800 Message-Id: <20220218005521.172832-10-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 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Jason Gunthorpe commit 60720a0fc646 ("vfio: Add device tracking during unbind") added the unbound list to plug a problem with KVM where KVM_DEV_VFIO_GROUP_DEL relied on vfio_group_get_external_user() succeeding to return the vfio_group from a group file descriptor. The unbound list allowed vfio_group_get_external_user() to continue to succeed in edge cases. However commit 5d6dee80a1e9 ("vfio: New external user group/file match") deleted the call to vfio_group_get_external_user() during KVM_DEV_VFIO_GROUP_DEL. Instead vfio_external_group_match_file() is used to directly match the file descriptor to the group pointer. This in turn avoids the call down to vfio_dev_viable() during KVM_DEV_VFIO_GROUP_DEL and also avoids the trouble the first commit was trying to fix. There are no other users of vfio_dev_viable() that care about the time after vfio_unregister_group_dev() returns, so simply delete the unbound_list entirely. Reviewed-by: Chaitanya Kulkarni Signed-off-by: Jason Gunthorpe Signed-off-by: Lu Baolu --- drivers/vfio/vfio.c | 74 ++------------------------------------------- 1 file changed, 2 insertions(+), 72 deletions(-) diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c index 73034446e03f..e0df2bc692b2 100644 --- a/drivers/vfio/vfio.c +++ b/drivers/vfio/vfio.c @@ -62,11 +62,6 @@ struct vfio_container { bool noiommu; }; -struct vfio_unbound_dev { - struct device *dev; - struct list_head unbound_next; -}; - struct vfio_group { struct device dev; struct cdev cdev; @@ -79,8 +74,6 @@ struct vfio_group { struct notifier_block nb; struct list_head vfio_next; struct list_head container_next; - struct list_head unbound_list; - struct mutex unbound_lock; atomic_t opened; wait_queue_head_t container_q; enum vfio_group_type type; @@ -340,16 +333,8 @@ vfio_group_get_from_iommu(struct iommu_group *iommu_group) static void vfio_group_release(struct device *dev) { struct vfio_group *group = container_of(dev, struct vfio_group, dev); - struct vfio_unbound_dev *unbound, *tmp; - - list_for_each_entry_safe(unbound, tmp, - &group->unbound_list, unbound_next) { - list_del(&unbound->unbound_next); - kfree(unbound); - } mutex_destroy(&group->device_lock); - mutex_destroy(&group->unbound_lock); iommu_group_put(group->iommu_group); ida_free(&vfio.group_ida, MINOR(group->dev.devt)); kfree(group); @@ -381,8 +366,6 @@ static struct vfio_group *vfio_group_alloc(struct iommu_group *iommu_group, refcount_set(&group->users, 1); INIT_LIST_HEAD(&group->device_list); mutex_init(&group->device_lock); - INIT_LIST_HEAD(&group->unbound_list); - mutex_init(&group->unbound_lock); init_waitqueue_head(&group->container_q); group->iommu_group = iommu_group; /* put in vfio_group_release() */ @@ -571,19 +554,8 @@ static int vfio_dev_viable(struct device *dev, void *data) struct vfio_group *group = data; struct vfio_device *device; struct device_driver *drv = READ_ONCE(dev->driver); - struct vfio_unbound_dev *unbound; - int ret = -EINVAL; - mutex_lock(&group->unbound_lock); - list_for_each_entry(unbound, &group->unbound_list, unbound_next) { - if (dev == unbound->dev) { - ret = 0; - break; - } - } - mutex_unlock(&group->unbound_lock); - - if (!ret || !drv || vfio_dev_driver_allowed(dev, drv)) + if (!drv || vfio_dev_driver_allowed(dev, drv)) return 0; device = vfio_group_get_device(group, dev); @@ -592,7 +564,7 @@ static int vfio_dev_viable(struct device *dev, void *data) return 0; } - return ret; + return -EINVAL; } /* @@ -634,7 +606,6 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, { struct vfio_group *group = container_of(nb, struct vfio_group, nb); struct device *dev = data; - struct vfio_unbound_dev *unbound; switch (action) { case IOMMU_GROUP_NOTIFY_ADD_DEVICE: @@ -663,28 +634,6 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb, __func__, iommu_group_id(group->iommu_group), dev->driver->name); break; - case IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER: - dev_dbg(dev, "%s: group %d unbound from driver\n", __func__, - iommu_group_id(group->iommu_group)); - /* - * XXX An unbound device in a live group is ok, but we'd - * really like to avoid the above BUG_ON by preventing other - * drivers from binding to it. Once that occurs, we have to - * stop the system to maintain isolation. At a minimum, we'd - * want a toggle to disable driver auto probe for this device. - */ - - mutex_lock(&group->unbound_lock); - list_for_each_entry(unbound, - &group->unbound_list, unbound_next) { - if (dev == unbound->dev) { - list_del(&unbound->unbound_next); - kfree(unbound); - break; - } - } - mutex_unlock(&group->unbound_lock); - break; } return NOTIFY_OK; } @@ -889,29 +838,10 @@ static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group, void vfio_unregister_group_dev(struct vfio_device *device) { struct vfio_group *group = device->group; - struct vfio_unbound_dev *unbound; unsigned int i = 0; bool interrupted = false; long rc; - /* - * When the device is removed from the group, the group suddenly - * becomes non-viable; the device has a driver (until the unbind - * completes), but it's not present in the group. This is bad news - * for any external users that need to re-acquire a group reference - * in order to match and release their existing reference. To - * solve this, we track such devices on the unbound_list to bridge - * the gap until they're fully unbound. - */ - unbound = kzalloc(sizeof(*unbound), GFP_KERNEL); - if (unbound) { - unbound->dev = device->dev; - mutex_lock(&group->unbound_lock); - list_add(&unbound->unbound_next, &group->unbound_list); - mutex_unlock(&group->unbound_lock); - } - WARN_ON(!unbound); - vfio_device_put(device); rc = try_wait_for_completion(&device->comp); while (rc <= 0) {