Let users call iommu_sva_init_device() with the IOMMU_SVA_FEAT_IOPF flag, that enables the I/O Page Fault queue. The IOMMU driver checks is the device supports a form of page fault, in which case they add the device to a fault queue. If the device doesn't support page faults, the IOMMU driver aborts iommu_sva_init_device().
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 <[email protected]> --- drivers/iommu/iommu-sva.c | 26 +++++++++++++++++++++++++- drivers/iommu/iommu.c | 6 +++--- include/linux/iommu.h | 2 ++ 3 files changed, 30 insertions(+), 4 deletions(-) diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c index ee86f00ee1b9..1588a523a214 100644 --- a/drivers/iommu/iommu-sva.c +++ b/drivers/iommu/iommu-sva.c @@ -443,6 +443,8 @@ static void iommu_notifier_release(struct mmu_notifier *mn, struct mm_struct *mm dev_WARN(bond->dev, "possible leak of PASID %u", io_mm->pasid); + iopf_queue_flush_dev(bond->dev, io_mm->pasid); + spin_lock(&iommu_sva_lock); next = list_next_entry(bond, mm_head); @@ -590,6 +592,12 @@ int __iommu_sva_unbind_device(struct device *dev, int pasid) goto out_unlock; } + /* + * Caller stopped the device from issuing PASIDs, now make sure they are + * out of the fault queue. + */ + iopf_queue_flush_dev(dev, pasid); + /* spin_lock_irq matches the one in wait_event_lock_irq */ spin_lock_irq(&iommu_sva_lock); list_for_each_entry(bond, ¶m->mm_list, dev_head) { @@ -615,6 +623,8 @@ static void __iommu_sva_unbind_device_all(struct device *dev) if (!param) return; + iopf_queue_flush_dev(dev, IOMMU_PASID_INVALID); + spin_lock_irq(&iommu_sva_lock); list_for_each_entry_safe(bond, next, ¶m->mm_list, dev_head) io_mm_detach_locked(bond, true); @@ -680,6 +690,9 @@ EXPORT_SYMBOL_GPL(iommu_sva_find); * overrides it. Similarly, @min_pasid overrides the lower PASID limit supported * by the IOMMU. * + * If the device should support recoverable I/O Page Faults (e.g. PCI PRI), the + * IOMMU_SVA_FEAT_IOPF feature must be requested. + * * @mm_exit is called when an address space bound to the device is about to be * torn down by exit_mmap. After @mm_exit returns, the device must not issue any * more transaction with the PASID given as argument. The handler gets an opaque @@ -707,7 +720,7 @@ int iommu_sva_init_device(struct device *dev, unsigned long features, if (!domain || !domain->ops->sva_init_device) return -ENODEV; - if (features) + if (features & ~IOMMU_SVA_FEAT_IOPF) return -EINVAL; param = kzalloc(sizeof(*param), GFP_KERNEL); @@ -734,10 +747,20 @@ int iommu_sva_init_device(struct device *dev, unsigned long features, if (ret) goto err_unlock; + if (features & IOMMU_SVA_FEAT_IOPF) { + ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, + dev); + if (ret) + goto err_shutdown; + } + dev->iommu_param->sva_param = param; mutex_unlock(&dev->iommu_param->sva_lock); return 0; +err_shutdown: + if (domain->ops->sva_shutdown_device) + domain->ops->sva_shutdown_device(dev); err_unlock: mutex_unlock(&dev->iommu_param->sva_lock); kfree(param); @@ -766,6 +789,7 @@ void iommu_sva_shutdown_device(struct device *dev) goto out_unlock; __iommu_sva_unbind_device_all(dev); + iommu_unregister_device_fault_handler(dev); if (domain->ops->sva_shutdown_device) domain->ops->sva_shutdown_device(dev); diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 7113fe398b70..b493f5c4fe64 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -2342,9 +2342,9 @@ EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids); * iommu_sva_init_device() must be called first, to initialize the required SVA * features. @flags must be a subset of these features. * - * The caller must pin down using get_user_pages*() all mappings shared with the - * device. mlock() isn't sufficient, as it doesn't prevent minor page faults - * (e.g. copy-on-write). + * If IOMMU_SVA_FEAT_IOPF isn't requested, the caller must pin down using + * get_user_pages*() all mappings shared with the device. mlock() isn't + * sufficient, as it doesn't prevent minor page faults (e.g. copy-on-write). * * On success, 0 is returned and @pasid contains a valid ID. Otherwise, an error * is returned. diff --git a/include/linux/iommu.h b/include/linux/iommu.h index b7cd00ae7358..ad2b18883ae2 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -65,6 +65,8 @@ typedef int (*iommu_mm_exit_handler_t)(struct device *dev, int pasid, void *); #define IOMMU_PASID_INVALID (-1) +#define IOMMU_SVA_FEAT_IOPF (1 << 0) + 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 */ -- 2.18.0 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
