Re: [PATCH v3 10/16] iommu: introduce device fault report API

Jacob Pan
2018-01-23T20:01:38Z

On Thu, 18 Jan 2018 19:24:52 +0000
Jean-Philippe Brucker <jean-philippe.brucker@arm.com> wrote:

> Hi Jacob,
>
> I've got minor comments after working with this patch, sorry for the
> multiple replies
>
> On 17/11/17 18:55, Jacob Pan wrote:
> [...]
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 829e9e9..97b7990 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -581,6 +581,12 @@ int iommu_group_add_device(struct iommu_group
> > *group, struct device *dev) goto err_free_name;
> > }
> >
> > + dev->iommu_param = kzalloc(sizeof(struct
> > iommu_fault_param), GFP_KERNEL);
>
> This should be "sizeof(struct iommu_param)" or maybe
> "sizeof(*dev->iommu_param)".
>
good catch, thanks,
> > + if (!dev->iommu_param) {
> > + ret = -ENOMEM;
> > + goto err_free_name;
> > + }
> > +
> > kobject_get(group->devices_kobj);
> >
> > dev->iommu_group = group;
> > @@ -657,7 +663,7 @@ 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;
> > @@ -791,6 +797,61 @@ int iommu_group_unregister_notifier(struct
> > iommu_group *group, }
> > EXPORT_SYMBOL_GPL(iommu_group_unregister_notifier);
> >
> > +int iommu_register_device_fault_handler(struct device *dev,
> > + iommu_dev_fault_handler_t
> > handler,
> > + void *data)
> > +{
> > + struct iommu_param *idata = dev->iommu_param;
> > +
> > + /*
> > + * Device iommu_param should have been allocated when
> > device is
> > + * added to its iommu_group.
> > + */
> > + if (!idata)
> > + return -EINVAL;
> > + /* Only allow one fault handler registered for each device
> > */
> > + if (idata->fault_param)
> > + return -EBUSY;
> > + get_device(dev);
> > + idata->fault_param =
> > + kzalloc(sizeof(struct iommu_fault_param),
> > GFP_KERNEL);
> > + if (!idata->fault_param)
> > + return -ENOMEM;
> > + idata->fault_param->handler = handler;
> > + idata->fault_param->data = data;
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(iommu_register_device_fault_handler);
> > +
> > +int iommu_unregister_device_fault_handler(struct device *dev)
> > +{
> > + struct iommu_param *idata = dev->iommu_param;
> > +
> > + if (!idata)
> > + return -EINVAL;
> > +
> > + kfree(idata->fault_param);
> > + idata->fault_param = NULL;
> > + put_device(dev);
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(iommu_unregister_device_fault_handler);
>
> We should probably document register() and unregister() functions
> since they are part of the device driver API. If it helps I came up
> with:
>
> /**
> * 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. If the fault is
> * recoverable (IOMMU_FAULT_PAGE_REQ), the handler must 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. */
>
> /**
> * iommu_unregister_device_fault_handler() - Unregister the device
> fault handler
> * @dev: the device
> *
> * Remove the device fault handler installed with
> * iommu_register_device_fault_handler().
> *
> * Return 0 on success, or an error.
> */
>
agreed. thanks. sorry about the delay.
> Thanks,
> Jean

[Jacob Pan]