Hi, On 05/15/2018 04:55 AM, Jacob Pan wrote: > On Mon, 14 May 2018 14:01:06 +0800 > Lu Baolu <baolu...@linux.intel.com> 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 <jacob.jun....@linux.intel.com> >>> Signed-off-by: Ashok Raj <ashok....@intel.com> >>> Signed-off-by: Jean-Philippe Brucker <jean-philippe.bruc...@arm.com> >>> --- >>> 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] > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
