iommu/process: Track process changes with an mmu_notifier

ascend inclusion
category: feature
bugzilla: 14369
CVE: NA

--------------

commit https://patchwork.ozlabs.org/patch/822423/

When creating an iommu_process structure, register a notifier to be
informed of changes to the virtual address space and to know when the
process exits.

Two new operations are added to the IOMMU driver:

* process_invalidate when a range of addresses is unmapped, to let the
  IOMMU driver send TLB invalidations.

* process_exit when the mm is released. It's a bit more involved in this
  case, as the IOMMU driver has to tell all devices drivers to stop using
  this PASID, then clear the PASID table and invalidate TLBs.

Adding the notifier in the mix complicates process release. In one case
device drivers free the process explicitly by calling unbind (or detaching
the device). In the other case the process could crash before unbind, in
which case the release notifier has to do all the work.
Signed-off-by: NJean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: NFang Lijun <fanglijun3@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

include/linux/iommu.h

@@ -122,9 +122,15 @@ struct iommu_process {
 	int			pasid;
 	struct list_head	domains;
 	struct kref		kref;
+#ifdef CONFIG_MMU_NOTIFIER
+	struct mmu_notifier	notifier;
+#endif
+	struct mm_struct	*mm;
 
 	/* Release callback for this process */
 	void (*release)(struct iommu_process *process);
+	/* For postponed release */
+	struct rcu_head		rcu;
 };
 
 struct io_mm {
@@ -278,6 +284,9 @@ struct iommu_sva_param {
  * @domain_free: free iommu domain
  * @attach_dev: attach device to an iommu domain
  * @detach_dev: detach device from an iommu domain
+ * @process_invalidate: Invalidate a range of mappings for a process.
+ * @process_exit: A process is exiting. Stop using the PASID, remove PASID entry
+ *                and flush associated TLB entries.
  * @sva_device_init: initialize Shared Virtual Adressing for a device
  * @sva_device_shutdown: shutdown Shared Virtual Adressing for a device
  * @mm_alloc: allocate io_mm
@@ -321,6 +330,10 @@ struct iommu_ops {
 
 	int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
 	void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
+	void (*process_invalidate)(struct iommu_domain *domain,
+				   struct iommu_process *process,
+				   unsigned long iova, size_t size);
+	void (*process_exit)(struct iommu_domain *domain, struct iommu_process *process);
 	int (*sva_device_init)(struct device *dev,
 			       struct iommu_sva_param *param);
 	void (*sva_device_shutdown)(struct device *dev,