arm64: mm: change IOMMU notifier action to attach DMA ops (16c11325) · Commits · 戴 / test

Current bus notifier in ARM64 (__iommu_attach_notifier) attempts to attach dma_ops to a device on BUS_NOTIFY_ADD_DEVICE action notification. This will cause issues on ACPI based systems, where PCI devices can be added before the IOMMUs the devices are attached to had a chance to be probed, causing failures on attempts to attach dma_ops in that the domain for the respective IOMMU may not be set-up yet by the time the bus notifier is run. Devices dma_ops do not require to be set-up till the matching device drivers are probed. This means that instead of running the notifier attaching dma_ops to devices (__iommu_attach_notifier) on BUS_NOTIFY_ADD_DEVICE action, it can be run just before the device driver is bound to the device in question (on action BUS_NOTIFY_BIND_DRIVER) so that it is certain that its IOMMU group and domain are set-up accordingly at the time the notifier is triggered. This patch changes the notifier action upon which dma_ops are attached to devices and defer it to driver binding time, so that IOMMU devices have a chance to be probed and to register their bus notifiers before the dma_ops attach sequence for a device is actually carried out. As a result we also no longer need worry about racing with iommu_bus_notifier(), or about retrying the queue in case devices were added too early on DT-based systems, so clean up the notifier itself plus the additional workaround from ("arm64: dma-mapping: fix handling of devices registered before arch_initcall") Acked-by:

Will Deacon <will.deacon@arm.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by:

Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> [rm: get rid of other now-redundant bits] Signed-off-by:

Robin Murphy <robin.murphy@arm.com> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/mm/dma-mapping.c

+5 −17

Original line number	Original line	Diff line number	Diff line
	@@ -861,15 +861,16 @@ static int __iommu_attach_notifier(struct notifier_block *nb,
	{		{
	struct iommu_dma_notifier_data master, tmp;		struct iommu_dma_notifier_data master, tmp;

	if (action != BUS_NOTIFY_ADD_DEVICE)		if (action != BUS_NOTIFY_BIND_DRIVER)
	return 0;		return 0;

	mutex_lock(&iommu_dma_notifier_lock);		mutex_lock(&iommu_dma_notifier_lock);
	list_for_each_entry_safe(master, tmp, &iommu_dma_masters, list) {		list_for_each_entry_safe(master, tmp, &iommu_dma_masters, list) {
	if (do_iommu_attach(master->dev, master->ops,		if (data == master->dev && do_iommu_attach(master->dev,
	master->dma_base, master->size)) {		master->ops, master->dma_base, master->size)) {
	list_del(&master->list);		list_del(&master->list);
	kfree(master);		kfree(master);
			break;
	}		}
	}		}
	mutex_unlock(&iommu_dma_notifier_lock);		mutex_unlock(&iommu_dma_notifier_lock);
	@@ -883,17 +884,8 @@ static int __init register_iommu_dma_ops_notifier(struct bus_type *bus)

	if (!nb)		if (!nb)
	return -ENOMEM;		return -ENOMEM;
	/*
	* The device must be attached to a domain before the driver probe
	* routine gets a chance to start allocating DMA buffers. However,
	* the IOMMU driver also needs a chance to configure the iommu_group
	* via its add_device callback first, so we need to make the attach
	* happen between those two points. Since the IOMMU core uses a bus
	* notifier with default priority for add_device, do the same but
	* with a lower priority to ensure the appropriate ordering.
	*/
	nb->notifier_call = __iommu_attach_notifier;		nb->notifier_call = __iommu_attach_notifier;
	nb->priority = -100;

	ret = bus_register_notifier(bus, nb);		ret = bus_register_notifier(bus, nb);
	if (ret) {		if (ret) {
	@@ -917,10 +909,6 @@ static int __init __iommu_dma_init(void)
	if (!ret)		if (!ret)
	ret = register_iommu_dma_ops_notifier(&pci_bus_type);		ret = register_iommu_dma_ops_notifier(&pci_bus_type);
	#endif		#endif

	/* handle devices queued before this arch_initcall */
	if (!ret)
	__iommu_attach_notifier(NULL, BUS_NOTIFY_ADD_DEVICE, NULL);
	return ret;		return ret;
	}		}
	arch_initcall(__iommu_dma_init);		arch_initcall(__iommu_dma_init);

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