From 16c11325cc44f0614a45e584d439e195059c3f5a Mon Sep 17 00:00:00 2001 From: Lorenzo Pieralisi Date: Fri, 1 Jul 2016 17:50:10 +0100 Subject: [PATCH] arm64: mm: change IOMMU notifier action to attach DMA ops 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 722ec35f7fae ("arm64: dma-mapping: fix handling of devices registered before arch_initcall") Acked-by: Will Deacon Cc: Marek Szyprowski Signed-off-by: Lorenzo Pieralisi [rm: get rid of other now-redundant bits] Signed-off-by: Robin Murphy Signed-off-by: Catalin Marinas --- arch/arm64/mm/dma-mapping.c | 22 +++++----------------- 1 file changed, 5 insertions(+), 17 deletions(-) diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 46a4157adc17..f6c55afab3e2 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -861,15 +861,16 @@ static int __iommu_attach_notifier(struct notifier_block *nb, { struct iommu_dma_notifier_data *master, *tmp; - if (action != BUS_NOTIFY_ADD_DEVICE) + if (action != BUS_NOTIFY_BIND_DRIVER) return 0; mutex_lock(&iommu_dma_notifier_lock); list_for_each_entry_safe(master, tmp, &iommu_dma_masters, list) { - if (do_iommu_attach(master->dev, master->ops, - master->dma_base, master->size)) { + if (data == master->dev && do_iommu_attach(master->dev, + master->ops, master->dma_base, master->size)) { list_del(&master->list); kfree(master); + break; } } mutex_unlock(&iommu_dma_notifier_lock); @@ -883,17 +884,8 @@ static int __init register_iommu_dma_ops_notifier(struct bus_type *bus) if (!nb) 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->priority = -100; ret = bus_register_notifier(bus, nb); if (ret) { @@ -917,10 +909,6 @@ static int __init __iommu_dma_init(void) if (!ret) ret = register_iommu_dma_ops_notifier(&pci_bus_type); #endif - - /* handle devices queued before this arch_initcall */ - if (!ret) - __iommu_attach_notifier(NULL, BUS_NOTIFY_ADD_DEVICE, NULL); return ret; } arch_initcall(__iommu_dma_init); -- 2.20.1