Re: [PATCH v4 12/22] iommu: introduce device fault report API

[Jean-Philippe Brucker]

On Mon, Apr 16, 2018 at 10:49:01PM +0100, Jacob Pan wrote:
[...]
> +int iommu_register_device_fault_handler(struct device *dev,
> +                                     iommu_dev_fault_handler_t handler,
> +                                     void *data)
> +{
> +     struct iommu_param *param = dev->iommu_param;
> +
> +     /*
> +      * Device iommu_param should have been allocated when device is
> +      * added to its iommu_group.
> +      */
> +     if (!param)
> +             return -EINVAL;
> +
> +     /* Only allow one fault handler registered for each device */
> +     if (param->fault_param)
> +             return -EBUSY;
> +
> +     mutex_lock(&param->lock);
> +     get_device(dev);
> +     param->fault_param =
> +             kzalloc(sizeof(struct iommu_fault_param), GFP_ATOMIC);

This can be GFP_KERNEL

[...]
> +int iommu_report_device_fault(struct device *dev, struct iommu_fault_event 
> *evt)
> +{
> +     int ret = 0;
> +     struct iommu_fault_event *evt_pending;
> +     struct iommu_fault_param *fparam;
> +
> +     /* iommu_param is allocated when device is added to group */
> +     if (!dev->iommu_param | !evt)
> +             return -EINVAL;
> +     /* we only report device fault if there is a handler registered */
> +     mutex_lock(&dev->iommu_param->lock);
> +     if (!dev->iommu_param->fault_param ||
> +             !dev->iommu_param->fault_param->handler) {
> +             ret = -EINVAL;
> +             goto done_unlock;
> +     }
> +     fparam = dev->iommu_param->fault_param;
> +     if (evt->type == IOMMU_FAULT_PAGE_REQ && evt->last_req) {
> +             evt_pending = kzalloc(sizeof(*evt_pending), GFP_ATOMIC);

We're expecting caller to be a thread at the moment, so this could be
GFP_KERNEL too. You could also use kmemdup to remove the memcpy below

[...]
> +static inline int iommu_register_device_fault_handler(struct device *dev,
> +                                             iommu_dev_fault_handler_t 
> handler,
> +                                             void *data)
> +{
> +     return 0;

Should return -ENODEV

Thanks,
Jean