When an mm exits, devices that were bound to it must stop performing DMA
on its PASID. Let device drivers register a callback to be notified on mm
exit. Add the callback to the iommu_param structure attached to struct
device.
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
drivers/iommu/iommu-sva.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/iommu.h | 18 ++++++++++++++++
2 files changed, 72 insertions(+)
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index f9af9d66b3ed..90b524c99d3d 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -569,3 +569,57 @@ void __iommu_sva_unbind_dev_all(struct device *dev)
spin_unlock(&iommu_sva_lock);
}
EXPORT_SYMBOL_GPL(__iommu_sva_unbind_dev_all);
+
+/**
+ * iommu_register_mm_exit_handler() - Set a callback for mm exit
+ * @dev: the device
+ * @handler: exit handler
+ *
+ * Users of the bind/unbind API should call this function to set a
+ * device-specific callback telling them when a mm is exiting.
+ *
+ * After the callback returns, the device must not issue any more transaction
+ * with the PASID given as argument to the handler. In addition the handler gets
+ * an opaque pointer corresponding to the drvdata passed as argument of bind().
+ *
+ * The handler itself should return 0 on success, and an appropriate error code
+ * otherwise.
+ */
+int iommu_register_mm_exit_handler(struct device *dev,
+ iommu_mm_exit_handler_t handler)
+{
+ struct iommu_param *dev_param = dev->iommu_param;
+
+ if (!dev_param)
+ return -EINVAL;
+
+ /*
+ * FIXME: racy. Same as iommu_sva_device_init, but here we'll need a
+ * spinlock to call the mm_exit param from atomic context.
+ */
+ if (dev_param->mm_exit)
+ return -EBUSY;
+
+ get_device(dev);
+ dev_param->mm_exit = handler;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iommu_register_mm_exit_handler);
+
+/**
+ * iommu_unregister_mm_exit_handler() - Remove mm exit callback
+ */
+int iommu_unregister_mm_exit_handler(struct device *dev)
+{
+ struct iommu_param *dev_param = dev->iommu_param;
+
+ if (!dev_param || !dev_param->mm_exit)
+ return -EINVAL;
+
+ dev_param->mm_exit = NULL;
+ put_device(dev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(iommu_unregister_mm_exit_handler);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 09d85f44142a..1b1a16892ac1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -65,6 +65,8 @@ typedef int (*iommu_dev_fault_handler_t)(struct iommu_fault_event *, void *);
/* Request I/O page fault support */
#define IOMMU_SVA_FEAT_IOPF (1 << 1)
+typedef int (*iommu_mm_exit_handler_t)(struct device *dev, int pasid, void *);
+
struct iommu_domain_geometry {
dma_addr_t aperture_start; /* First address that can be mapped */
dma_addr_t aperture_end; /* Last address that can be mapped */
@@ -424,6 +426,7 @@ struct iommu_param {
unsigned int min_pasid;
unsigned int max_pasid;
struct list_head mm_list;
+ iommu_mm_exit_handler_t mm_exit;
};
int iommu_device_register(struct iommu_device *iommu);
@@ -941,6 +944,10 @@ extern int iommu_sva_bind_device(struct device *dev, struct mm_struct *mm,
int *pasid, unsigned long flags, void *drvdata);
extern int iommu_sva_unbind_device(struct device *dev, int pasid);
extern void __iommu_sva_unbind_dev_all(struct device *dev);
+extern int iommu_register_mm_exit_handler(struct device *dev,
+ iommu_mm_exit_handler_t handler);
+extern int iommu_unregister_mm_exit_handler(struct device *dev);
+
#else /* CONFIG_IOMMU_SVA */
static inline int iommu_sva_device_init(struct device *dev,
unsigned long features,
@@ -969,6 +976,17 @@ static inline int iommu_sva_unbind_device(struct device *dev, int pasid)
static inline void __iommu_sva_unbind_dev_all(struct device *dev)
{
}
+
+static inline int iommu_register_mm_exit_handler(struct device *dev,
+ iommu_mm_exit_handler_t handler)
+{
+ return -ENODEV;
+}
+
+static inline int iommu_unregister_mm_exit_handler(struct device *dev)
+{
+ return -ENODEV;
+}
#endif /* CONFIG_IOMMU_SVA */
#endif /* __LINUX_IOMMU_H */
--
2.15.1
