[PATCH v4 06/26] iommu/sva: Register page fault handler

[Jean-Philippe Brucker]

From: Jean-Philippe Brucker <jean-philippe.bruc...@arm.com>

When enabling SVA, register the fault handler. Device driver will register
an I/O page fault queue before or after calling iommu_sva_enable. The
fault queue must be flushed before any io_mm is freed, to make sure that
its PASID isn't used in any fault queue, and can be reallocated. Add
iopf_queue_flush() calls in a few strategic locations.

Signed-off-by: Jean-Philippe Brucker <jean-phili...@linaro.org>
---
 drivers/iommu/Kconfig     |  1 +
 drivers/iommu/iommu-sva.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index e4a42e1708b4..211684e785ea 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -106,6 +106,7 @@ config IOMMU_DMA
 config IOMMU_SVA
        bool
        select IOASID
+       select IOMMU_PAGE_FAULT
        select IOMMU_API
        select MMU_NOTIFIER
 
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index bfd0c477f290..494ca0824e4b 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -366,6 +366,8 @@ static void io_mm_release(struct mmu_notifier *mn, struct 
mm_struct *mm)
                        dev_WARN(dev, "possible leak of PASID %u",
                                 io_mm->pasid);
 
+               iopf_queue_flush_dev(dev, io_mm->pasid);
+
                /* unbind() frees the bond, we just detach it */
                io_mm_detach_locked(bond);
        }
@@ -442,11 +444,20 @@ static void iommu_sva_unbind_locked(struct iommu_bond 
*bond)
 
 void iommu_sva_unbind_generic(struct iommu_sva *handle)
 {
+       int pasid;
        struct iommu_param *param = handle->dev->iommu_param;
 
        if (WARN_ON(!param))
                return;
 
+       /*
+        * Caller stopped the device from issuing PASIDs, now make sure they are
+        * out of the fault queue.
+        */
+       pasid = iommu_sva_get_pasid_generic(handle);
+       if (pasid != IOMMU_PASID_INVALID)
+               iopf_queue_flush_dev(handle->dev, pasid);
+
        mutex_lock(&param->sva_lock);
        mutex_lock(&iommu_sva_lock);
        iommu_sva_unbind_locked(to_iommu_bond(handle));
@@ -484,6 +495,10 @@ int iommu_sva_enable(struct device *dev, struct 
iommu_sva_param *sva_param)
                goto err_unlock;
        }
 
+       ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev);
+       if (ret)
+               goto err_unlock;
+
        dev->iommu_param->sva_param = new_param;
        mutex_unlock(&param->sva_lock);
        return 0;
@@ -521,6 +536,7 @@ int iommu_sva_disable(struct device *dev)
                goto out_unlock;
        }
 
+       iommu_unregister_device_fault_handler(dev);
        kfree(param->sva_param);
        param->sva_param = NULL;
 out_unlock:
-- 
2.25.0

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