From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZoCMXei/IT/LglhNI2HKqZQ9c45wIrrRSoIgtOToaq00yc2BOvdqEDPTpznX5K6rIZUM686 ARC-Seal: i=1; a=rsa-sha256; t=1526367182; cv=none; d=google.com; s=arc-20160816; b=zqSVsHY1WQcGZ1eN37IrYsNRa+VwU3xo3HPoLJC3meUctmzY0sCAAtPNbu2KDVzKPn 3DIvWi35uOM+eIJnM2Zl1CznNlBf1+X7BQ9ZIJY7UBQ/4Xq6xzSiTUMzxLl5/ptqpyjW Aa12oUdNREnh8+V7O5LIhVLCYqM6Rqf3HrwBPAilOj+fenfCD2X0rtjfXowQWAe1kwyB OBZ1edKyQPWOogRXN/4oAGPf1DiprYPXYpuXzYDzMhch7v+2XNbsG4EFtTnenlatpmFv 9qeT48ul83298ntJlteqAUFi2o+cINo3anvArloFJhMazObqNQH9THBvNfRUlSq3ILLf 2wQA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:in-reply-to:mime-version:user-agent:date :message-id:from:cc:references:to:subject:arc-authentication-results; bh=VD5MwQ/ZNWVNn5eQPgpNMf3CtyQ/lQ6QFuFoILM2z14=; b=yG0IfLug/23ICYsUW9Ogi4RR0u14xpp3fpIYkLyo+G5ojy6eoZHk5GcQd7HjTrFu6G M0yEWcGUlDGA8prsXcaJHOsML0Z0JaSMuLicDQr+Gi9eqgSxAhbsjDMwNhKdVnxoo0T6 f2rdqbU0HkvdsYu2AetwtxEuTMCev9SXQrbsrC+K0ZUizmo0jrV4RvBoMxnkEw0pej2o 0xSpNwNHXMRWlj7e4xqPYWO4Fmajmc+oiwRtdEmvKuO7SlYdoWnpKUk7ZEuxco1ZxOLW we7QSnjQL8SzYfnOlH2lEwgsZKIeBxByKcJOVTVnU69x8KwzcGEM4+SV7LTyANX8LqNo VyLg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of baolu.lu@linux.intel.com designates 192.55.52.115 as permitted sender) smtp.mailfrom=baolu.lu@linux.intel.com Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of baolu.lu@linux.intel.com designates 192.55.52.115 as permitted sender) smtp.mailfrom=baolu.lu@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="5.49,403,1520924400"; d="scan'208";a="55277498" Subject: Re: [PATCH v5 13/23] iommu: introduce device fault report API To: Jacob Pan 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> <20180514135548.4b95ab93@jacob-builder> 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 From: Lu Baolu Message-ID: <5AFA83CB.2040301@linux.intel.com> Date: Tue, 15 May 2018 14:52:59 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20180514135548.4b95ab93@jacob-builder> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1600202363226135285?= X-GMAIL-MSGID: =?utf-8?q?1600511994899865791?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hi, On 05/15/2018 04:55 AM, Jacob Pan wrote: > 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. Okay, got it. Best regards, Lu Baolu >> [...] >> >> Best regards, >> Lu Baolu > [Jacob Pan] >