Add bind and unbind operations to the IOMMU API. Device drivers can use them to share process page tables with their device. iommu_process_bind_group is provided for VFIO's convenience, as it needs to provide a coherent interface on containers. Device drivers will most likely want to use iommu_process_bind_device, which doesn't bind the whole group.
PASIDs are de facto shared between all devices in a group (because of hardware weaknesses), but we don't do anything about it at the API level. Making bind_device call bind_group is probably the wrong way around, because it requires more work on our side for no benefit. We'd have to replay all binds each time a device is hotplugged into a group. But when a device is hotplugged into a group, the device driver will have to do a bind before using its PASID anyway and we can reject inconsistencies at that point. Concurrent calls to iommu_process_bind_device for the same process are not supported at the moment (they'll race on process_alloc which will only succeed for the first one; the others will have to retry the bind). I also don't support calling bind() on a dying process, not sure if it matters. Signed-off-by: Jean-Philippe Brucker <[email protected]> --- drivers/iommu/iommu-process.c | 165 ++++++++++++++++++++++++++++++++++++++++++ drivers/iommu/iommu.c | 64 ++++++++++++++++ include/linux/iommu.h | 41 +++++++++++ 3 files changed, 270 insertions(+) diff --git a/drivers/iommu/iommu-process.c b/drivers/iommu/iommu-process.c index 1ef3f55b962b..dee7691e3791 100644 --- a/drivers/iommu/iommu-process.c +++ b/drivers/iommu/iommu-process.c @@ -411,6 +411,171 @@ static struct mmu_notifier_ops iommu_process_mmu_notfier = { }; /** + * iommu_process_bind_device - Bind a process address space to a device + * @dev: the device + * @task: the process to bind + * @pasid: valid address where the PASID will be stored + * @flags: bond properties (IOMMU_PROCESS_BIND_*) + * + * Create a bond between device and task, allowing the device to access the + * process address space using the returned PASID. + * + * On success, 0 is returned and @pasid contains a valid ID. Otherwise, an error + * is returned. + */ +int iommu_process_bind_device(struct device *dev, struct task_struct *task, + int *pasid, int flags) +{ + int err, i; + int nesting; + struct pid *pid; + struct iommu_domain *domain; + struct iommu_process *process; + struct iommu_context *cur_context; + struct iommu_context *context = NULL; + + domain = iommu_get_domain_for_dev(dev); + if (WARN_ON(!domain)) + return -EINVAL; + + if (!iommu_domain_get_attr(domain, DOMAIN_ATTR_NESTING, &nesting) && + nesting) + return -EINVAL; + + pid = get_task_pid(task, PIDTYPE_PID); + if (!pid) + return -EINVAL; + + /* If an iommu_process already exists, use it */ + spin_lock(&iommu_process_lock); + idr_for_each_entry(&iommu_process_idr, process, i) { + if (process->pid != pid) + continue; + + if (!iommu_process_get_locked(process)) { + /* Process is defunct, create a new one */ + process = NULL; + break; + } + + /* Great, is it also bound to this domain? */ + list_for_each_entry(cur_context, &process->domains, + process_head) { + if (cur_context->domain != domain) + continue; + + context = cur_context; + *pasid = process->pasid; + + /* Splendid, tell the driver and increase the ref */ + err = iommu_process_attach_locked(context, dev); + if (err) + iommu_process_put_locked(process); + + break; + } + break; + } + spin_unlock(&iommu_process_lock); + put_pid(pid); + + if (context) + return err; + + if (!process) { + process = iommu_process_alloc(domain, task); + if (IS_ERR(process)) + return PTR_ERR(process); + } + + err = iommu_process_attach(domain, dev, process); + if (err) { + iommu_process_put(process); + return err; + } + + *pasid = process->pasid; + + return 0; +} +EXPORT_SYMBOL_GPL(iommu_process_bind_device); + +/** + * iommu_process_unbind_device - Remove a bond created with + * iommu_process_bind_device. + * + * @dev: the device + * @pasid: the pasid returned by bind + */ +int iommu_process_unbind_device(struct device *dev, int pasid) +{ + struct iommu_domain *domain; + struct iommu_process *process; + struct iommu_context *cur_context; + struct iommu_context *context = NULL; + + domain = iommu_get_domain_for_dev(dev); + if (WARN_ON(!domain)) + return -EINVAL; + + /* + * Caller stopped the device from issuing PASIDs, now make sure they are + * out of the fault queue. + */ + iommu_fault_queue_flush(dev); + + spin_lock(&iommu_process_lock); + process = idr_find(&iommu_process_idr, pasid); + if (!process) { + spin_unlock(&iommu_process_lock); + return -ESRCH; + } + + list_for_each_entry(cur_context, &process->domains, process_head) { + if (cur_context->domain == domain) { + context = cur_context; + break; + } + } + + if (context) + iommu_process_detach_locked(context, dev); + spin_unlock(&iommu_process_lock); + + return context ? 0 : -ESRCH; +} +EXPORT_SYMBOL_GPL(iommu_process_unbind_device); + +/* + * __iommu_process_unbind_dev_all - Detach all processes attached to this + * device. + * + * When detaching @device from @domain, IOMMU drivers have to use this function. + */ +void __iommu_process_unbind_dev_all(struct iommu_domain *domain, struct device *dev) +{ + struct iommu_context *context, *next; + + /* Ask device driver to stop using all PASIDs */ + spin_lock(&iommu_process_lock); + if (domain->process_exit) { + list_for_each_entry(context, &domain->processes, domain_head) + domain->process_exit(domain, dev, + context->process->pasid, + domain->process_exit_token); + } + spin_unlock(&iommu_process_lock); + + iommu_fault_queue_flush(dev); + + spin_lock(&iommu_process_lock); + list_for_each_entry_safe(context, next, &domain->processes, domain_head) + iommu_process_detach_locked(context, dev); + spin_unlock(&iommu_process_lock); +} +EXPORT_SYMBOL_GPL(__iommu_process_unbind_dev_all); + +/** * iommu_set_process_exit_handler() - set a callback for stopping the use of * PASID in a device. * @dev: the device diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index b2b34cf7c978..f9cb89dd28f5 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -1460,6 +1460,70 @@ void iommu_detach_group(struct iommu_domain *domain, struct iommu_group *group) } EXPORT_SYMBOL_GPL(iommu_detach_group); +/* + * iommu_process_bind_group - Share process address space with all devices in + * the group. + * @group: the iommu group + * @task: the process to bind + * @pasid: valid address where the PASID will be stored + * @flags: bond properties (IOMMU_PROCESS_BIND_*) + * + * Create a bond between group and process, allowing devices in the group to + * access the process address space using @pasid. + * + * On success, 0 is returned and @pasid contains a valid ID. Otherwise, an error + * is returned. + */ +int iommu_process_bind_group(struct iommu_group *group, + struct task_struct *task, int *pasid, int flags) +{ + struct group_device *device; + int ret = -ENODEV; + + if (!pasid) + return -EINVAL; + + if (!group->domain) + return -EINVAL; + + mutex_lock(&group->mutex); + list_for_each_entry(device, &group->devices, list) { + ret = iommu_process_bind_device(device->dev, task, pasid, + flags); + if (ret) + break; + } + + if (ret) { + list_for_each_entry_continue_reverse(device, &group->devices, list) + iommu_process_unbind_device(device->dev, *pasid); + } + mutex_unlock(&group->mutex); + + return ret; +} +EXPORT_SYMBOL_GPL(iommu_process_bind_group); + +/** + * iommu_process_unbind_group - Remove a bond created with + * iommu_process_bind_group + * + * @group: the group + * @pasid: the pasid returned by bind + */ +int iommu_process_unbind_group(struct iommu_group *group, int pasid) +{ + struct group_device *device; + + mutex_lock(&group->mutex); + list_for_each_entry(device, &group->devices, list) + iommu_process_unbind_device(device->dev, pasid); + mutex_unlock(&group->mutex); + + return 0; +} +EXPORT_SYMBOL_GPL(iommu_process_unbind_group); + phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova) { if (unlikely(domain->ops->iova_to_phys == NULL)) diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 42b818437fa1..e64c2711ea8d 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -454,6 +454,10 @@ int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode, void iommu_fwspec_free(struct device *dev); int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids); const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode); +extern int iommu_process_bind_group(struct iommu_group *group, + struct task_struct *task, int *pasid, + int flags); +extern int iommu_process_unbind_group(struct iommu_group *group, int pasid); #else /* CONFIG_IOMMU_API */ @@ -739,6 +743,19 @@ const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode) return NULL; } +static inline int iommu_process_bind_group(struct iommu_group *group, + struct task_struct *task, int *pasid, + int flags) +{ + return -ENODEV; +} + +static inline int iommu_process_unbind_group(struct iommu_group *group, + int pasid) +{ + return -ENODEV; +} + #endif /* CONFIG_IOMMU_API */ #ifdef CONFIG_IOMMU_PROCESS @@ -747,6 +764,12 @@ extern void iommu_set_process_exit_handler(struct device *dev, void *token); extern struct iommu_process *iommu_process_find(int pasid); extern void iommu_process_put(struct iommu_process *process); +extern int iommu_process_bind_device(struct device *dev, + struct task_struct *task, int *pasid, + int flags); +extern int iommu_process_unbind_device(struct device *dev, int pasid); +extern void __iommu_process_unbind_dev_all(struct iommu_domain *domain, + struct device *dev); #else /* CONFIG_IOMMU_PROCESS */ static inline void iommu_set_process_exit_handler(struct device *dev, @@ -763,6 +786,24 @@ static inline struct iommu_process *iommu_process_find(int pasid) static inline void iommu_process_put(struct iommu_process *process) { } + +static inline int iommu_process_bind_device(struct device *dev, + struct task_struct *task, + int *pasid, int flags) +{ + return -ENODEV; +} + +static inline int iommu_process_unbind_device(struct device *dev, int pasid) +{ + return -ENODEV; +} + +static inline void __iommu_process_unbind_dev_all(struct iommu_domain *domain, + struct device *dev) +{ +} + #endif /* CONFIG_IOMMU_PROCESS */ #endif /* __LINUX_IOMMU_H */ -- 2.13.3 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
