From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZp2OsLdabP4r5JMeOXc9K9Og0OcfaCz3QiuHmx7OEOMqhlNHTAjexz2sLG2ut3MIqQDd/YL ARC-Seal: i=1; a=rsa-sha256; t=1526331184; cv=none; d=google.com; s=arc-20160816; b=DUPj4tdl3j3Ea1x7hy1GSa63bKc8I6BhESeNBK3YcffO8NG79P9mAOsinLIkLIEYc/ 8k/FWT5YDG6MKkLadQDJM1Oq4FFOkho6knvdAgf1FsvFtH+ZXuskm9qkBwqxSwZuvFn5 +O17pA1Kae7W0s2/hIYsMp76ocwPWt959Kd/sCFXXlnLY9UuNF9lUcD0XBKQ17txtSui mTzzGxmZM3pjMkRxz6g30QKYq0ndiC9C9y3T7UpeT0C1XFg+L6PFv10fdCgh9BVOFvLh LBU9d3UjZ3t5beWbef3LAvaQW7Vo+9TjuABp4PLxO619B6fMqCAQfifLL5svnqKwaq5q Tlfg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:organization:references :in-reply-to:message-id:subject:cc:to:from:date :arc-authentication-results; bh=huAIyzi8Q6NdUZCs7rtY43MNqjJSqyM/2jhQgL0yWSU=; b=nOhICA/5/9Bm2IH5bl1+0yB98QeTTjEEFGpKMdQIouwQl/AMjH8eGKAAfguWfUwk7L 68ZiYmcp0UlJHuXFzCqKccXGn9utpx9/s5ykRUc60IUCCfZDootbVXnWZdHTh8xQ7Jkm uM105fjUuVjsFQX5A74k/lyQKjC5bkIY/6aQ0bYLiuMXkr07alvJFrpGGB/f2jndCqvA R9lRWonnhy9xA2AWbptWnpeDuqK0dcgHeWigSIIHDX3VSk5bZlQWaGgLIwdrNhUtY6Q8 QSr25O4TmHMpPprVucltH3UsN2IJUR76M/hjgGeIoelz0u4BzcTA2NviTzemP++8EHmC AEUA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of jacob.jun.pan@linux.intel.com designates 192.55.52.136 as permitted sender) smtp.mailfrom=jacob.jun.pan@linux.intel.com Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of jacob.jun.pan@linux.intel.com designates 192.55.52.136 as permitted sender) smtp.mailfrom=jacob.jun.pan@linux.intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.49,401,1520924400"; d="scan'208";a="199319611" Date: Mon, 14 May 2018 13:55:48 -0700 From: Jacob Pan To: Lu Baolu Cc: iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Greg Kroah-Hartman , Alex Williamson , Jean-Philippe Brucker , Rafael Wysocki , "Liu, Yi L" , "Tian, Kevin" , Raj Ashok , Jean Delvare , Christoph Hellwig , jacob.jun.pan@linux.intel.com Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API Message-ID: <20180514135548.4b95ab93@jacob-builder> In-Reply-To: <5AF92622.2090902@linux.intel.com> References: <1526072055-86990-1-git-send-email-jacob.jun.pan@linux.intel.com> <1526072055-86990-14-git-send-email-jacob.jun.pan@linux.intel.com> <5AF92622.2090902@linux.intel.com> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1600202363226135285?= X-GMAIL-MSGID: =?utf-8?q?1600474246812823646?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, 14 May 2018 14:01:06 +0800 Lu Baolu wrote: > Hi, > > On 05/12/2018 04:54 AM, Jacob Pan wrote: > > Traditionally, device specific faults are detected and handled > > within their own device drivers. When IOMMU is enabled, faults such > > as DMA related transactions are detected by IOMMU. There is no > > generic reporting mechanism to report faults back to the in-kernel > > device driver or the guest OS in case of assigned devices. > > > > Faults detected by IOMMU is based on the transaction's source ID > > which can be reported at per device basis, regardless of the device > > type is a PCI device or not. > > > > The fault types include recoverable (e.g. page request) and > > unrecoverable faults(e.g. access error). In most cases, faults can > > be handled by IOMMU drivers internally. The primary use cases are as > > follows: > > 1. page request fault originated from an SVM capable device that is > > assigned to guest via vIOMMU. In this case, the first level page > > tables are owned by the guest. Page request must be propagated to > > the guest to let guest OS fault in the pages then send page > > response. In this mechanism, the direct receiver of IOMMU fault > > notification is VFIO, which can relay notification events to QEMU > > or other user space software. > > > > 2. faults need more subtle handling by device drivers. Other than > > simply invoke reset function, there are needs to let device driver > > handle the fault with a smaller impact. > > > > This patchset is intended to create a generic fault report API such > > that it can scale as follows: > > - all IOMMU types > > - PCI and non-PCI devices > > - recoverable and unrecoverable faults > > - VFIO and other other in kernel users > > - DMA & IRQ remapping (TBD) > > The original idea was brought up by David Woodhouse and discussions > > summarized at https://lwn.net/Articles/608914/. > > > > Signed-off-by: Jacob Pan > > Signed-off-by: Ashok Raj > > Signed-off-by: Jean-Philippe Brucker > > --- > > drivers/iommu/iommu.c | 149 > > +++++++++++++++++++++++++++++++++++++++++++++++++- > > include/linux/iommu.h | 35 +++++++++++- 2 files changed, 181 > > insertions(+), 3 deletions(-) > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > index 3a49b96..b3f9daf 100644 > > --- a/drivers/iommu/iommu.c > > +++ b/drivers/iommu/iommu.c > > @@ -609,6 +609,13 @@ int iommu_group_add_device(struct iommu_group > > *group, struct device *dev) goto err_free_name; > > } > > > > + dev->iommu_param = kzalloc(sizeof(*dev->iommu_param), > > GFP_KERNEL); > > + if (!dev->iommu_param) { > > + ret = -ENOMEM; > > + goto err_free_name; > > + } > > + mutex_init(&dev->iommu_param->lock); > > + > > kobject_get(group->devices_kobj); > > > > dev->iommu_group = group; > > @@ -639,6 +646,7 @@ int iommu_group_add_device(struct iommu_group > > *group, struct device *dev) mutex_unlock(&group->mutex); > > dev->iommu_group = NULL; > > kobject_put(group->devices_kobj); > > + kfree(dev->iommu_param); > > err_free_name: > > kfree(device->name); > > err_remove_link: > > @@ -685,7 +693,7 @@ void iommu_group_remove_device(struct device > > *dev) sysfs_remove_link(&dev->kobj, "iommu_group"); > > > > trace_remove_device_from_group(group->id, dev); > > - > > + kfree(dev->iommu_param); > > kfree(device->name); > > kfree(device); > > dev->iommu_group = NULL; > > @@ -820,6 +828,145 @@ int iommu_group_unregister_notifier(struct > > iommu_group *group, > > EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); > > /** > > + * iommu_register_device_fault_handler() - Register a device fault > > handler > > + * @dev: the device > > + * @handler: the fault handler > > + * @data: private data passed as argument to the handler > > + * > > + * When an IOMMU fault event is received, call this handler with > > the fault event > > + * and data as argument. The handler should return 0 on success. > > If the fault is > > + * recoverable (IOMMU_FAULT_PAGE_REQ), the handler can also > > complete > > + * the fault by calling iommu_page_response() with one of the > > following > > + * response code: > > + * - IOMMU_PAGE_RESP_SUCCESS: retry the translation > > + * - IOMMU_PAGE_RESP_INVALID: terminate the fault > > + * - IOMMU_PAGE_RESP_FAILURE: terminate the fault and stop > > reporting > > + * page faults if possible. > > + * > > + * Return 0 if the fault handler was installed successfully, or an > > error. > > + */ > > +int iommu_register_device_fault_handler(struct device *dev, > > + iommu_dev_fault_handler_t > > handler, > > + void *data) > > +{ > > + struct iommu_param *param = dev->iommu_param; > > + int ret = 0; > > + > > + /* > > + * Device iommu_param should have been allocated when > > device is > > + * added to its iommu_group. > > + */ > > + if (!param) > > + return -EINVAL; > > + > > + mutex_lock(¶m->lock); > > + /* Only allow one fault handler registered for each device > > */ > > + if (param->fault_param) { > > + ret = -EBUSY; > > + goto done_unlock; > > + } > > + > > + get_device(dev); > > + param->fault_param = > > + kzalloc(sizeof(struct iommu_fault_param), > > GFP_KERNEL); > > + if (!param->fault_param) { > > + put_device(dev); > > + ret = -ENOMEM; > > + goto done_unlock; > > + } > > + mutex_init(¶m->fault_param->lock); > > Do we really need this mutex lock? Is param->lock enough? > I am trying to provide more fine locking granularity in that iommu_param is meant to be expanded as the sole iommu data under struct device, so the scope of param->lock may expand. > [...] > > Best regards, > Lu Baolu [Jacob Pan] From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacob Pan Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API Date: Mon, 14 May 2018 13:55:48 -0700 Message-ID: <20180514135548.4b95ab93@jacob-builder> References: <1526072055-86990-1-git-send-email-jacob.jun.pan@linux.intel.com> <1526072055-86990-14-git-send-email-jacob.jun.pan@linux.intel.com> <5AF92622.2090902@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5AF92622.2090902-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Lu Baolu Cc: Raj Ashok , Greg Kroah-Hartman , Rafael Wysocki , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, LKML , Jean Delvare , David Woodhouse List-Id: iommu@lists.linux-foundation.org On Mon, 14 May 2018 14:01:06 +0800 Lu Baolu wrote: > Hi, > > On 05/12/2018 04:54 AM, Jacob Pan wrote: > > Traditionally, device specific faults are detected and handled > > within their own device drivers. When IOMMU is enabled, faults such > > as DMA related transactions are detected by IOMMU. There is no > > generic reporting mechanism to report faults back to the in-kernel > > device driver or the guest OS in case of assigned devices. > > > > Faults detected by IOMMU is based on the transaction's source ID > > which can be reported at per device basis, regardless of the device > > type is a PCI device or not. > > > > The fault types include recoverable (e.g. page request) and > > unrecoverable faults(e.g. access error). In most cases, faults can > > be handled by IOMMU drivers internally. The primary use cases are as > > follows: > > 1. page request fault originated from an SVM capable device that is > > assigned to guest via vIOMMU. In this case, the first level page > > tables are owned by the guest. Page request must be propagated to > > the guest to let guest OS fault in the pages then send page > > response. In this mechanism, the direct receiver of IOMMU fault > > notification is VFIO, which can relay notification events to QEMU > > or other user space software. > > > > 2. faults need more subtle handling by device drivers. Other than > > simply invoke reset function, there are needs to let device driver > > handle the fault with a smaller impact. > > > > This patchset is intended to create a generic fault report API such > > that it can scale as follows: > > - all IOMMU types > > - PCI and non-PCI devices > > - recoverable and unrecoverable faults > > - VFIO and other other in kernel users > > - DMA & IRQ remapping (TBD) > > The original idea was brought up by David Woodhouse and discussions > > summarized at https://lwn.net/Articles/608914/. > > > > Signed-off-by: Jacob Pan > > Signed-off-by: Ashok Raj > > Signed-off-by: Jean-Philippe Brucker > > --- > > drivers/iommu/iommu.c | 149 > > +++++++++++++++++++++++++++++++++++++++++++++++++- > > include/linux/iommu.h | 35 +++++++++++- 2 files changed, 181 > > insertions(+), 3 deletions(-) > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > index 3a49b96..b3f9daf 100644 > > --- a/drivers/iommu/iommu.c > > +++ b/drivers/iommu/iommu.c > > @@ -609,6 +609,13 @@ int iommu_group_add_device(struct iommu_group > > *group, struct device *dev) goto err_free_name; > > } > > > > + dev->iommu_param = kzalloc(sizeof(*dev->iommu_param), > > GFP_KERNEL); > > + if (!dev->iommu_param) { > > + ret = -ENOMEM; > > + goto err_free_name; > > + } > > + mutex_init(&dev->iommu_param->lock); > > + > > kobject_get(group->devices_kobj); > > > > dev->iommu_group = group; > > @@ -639,6 +646,7 @@ int iommu_group_add_device(struct iommu_group > > *group, struct device *dev) mutex_unlock(&group->mutex); > > dev->iommu_group = NULL; > > kobject_put(group->devices_kobj); > > + kfree(dev->iommu_param); > > err_free_name: > > kfree(device->name); > > err_remove_link: > > @@ -685,7 +693,7 @@ void iommu_group_remove_device(struct device > > *dev) sysfs_remove_link(&dev->kobj, "iommu_group"); > > > > trace_remove_device_from_group(group->id, dev); > > - > > + kfree(dev->iommu_param); > > kfree(device->name); > > kfree(device); > > dev->iommu_group = NULL; > > @@ -820,6 +828,145 @@ int iommu_group_unregister_notifier(struct > > iommu_group *group, > > EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier); > > /** > > + * iommu_register_device_fault_handler() - Register a device fault > > handler > > + * @dev: the device > > + * @handler: the fault handler > > + * @data: private data passed as argument to the handler > > + * > > + * When an IOMMU fault event is received, call this handler with > > the fault event > > + * and data as argument. The handler should return 0 on success. > > If the fault is > > + * recoverable (IOMMU_FAULT_PAGE_REQ), the handler can also > > complete > > + * the fault by calling iommu_page_response() with one of the > > following > > + * response code: > > + * - IOMMU_PAGE_RESP_SUCCESS: retry the translation > > + * - IOMMU_PAGE_RESP_INVALID: terminate the fault > > + * - IOMMU_PAGE_RESP_FAILURE: terminate the fault and stop > > reporting > > + * page faults if possible. > > + * > > + * Return 0 if the fault handler was installed successfully, or an > > error. > > + */ > > +int iommu_register_device_fault_handler(struct device *dev, > > + iommu_dev_fault_handler_t > > handler, > > + void *data) > > +{ > > + struct iommu_param *param = dev->iommu_param; > > + int ret = 0; > > + > > + /* > > + * Device iommu_param should have been allocated when > > device is > > + * added to its iommu_group. > > + */ > > + if (!param) > > + return -EINVAL; > > + > > + mutex_lock(¶m->lock); > > + /* Only allow one fault handler registered for each device > > */ > > + if (param->fault_param) { > > + ret = -EBUSY; > > + goto done_unlock; > > + } > > + > > + get_device(dev); > > + param->fault_param = > > + kzalloc(sizeof(struct iommu_fault_param), > > GFP_KERNEL); > > + if (!param->fault_param) { > > + put_device(dev); > > + ret = -ENOMEM; > > + goto done_unlock; > > + } > > + mutex_init(¶m->fault_param->lock); > > Do we really need this mutex lock? Is param->lock enough? > I am trying to provide more fine locking granularity in that iommu_param is meant to be expanded as the sole iommu data under struct device, so the scope of param->lock may expand. > [...] > > Best regards, > Lu Baolu [Jacob Pan]