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. > [...] > > Best regards, > Lu Baolu [Jacob Pan] _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
