Messages in this thread Patch in this message | | | From | Lorenzo Pieralisi <> | Subject | [RFC PATCH v2 03/15] arm64: mm: change IOMMU notifier action to attach DMA ops | Date | Tue, 7 Jun 2016 14:30:58 +0100 |
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Current bus notifier in ARM64 (__iommu_attach_notifier) attempts to attach dma_ops to a device on BUS_NOTIFY_ADD_DEVICE action notification.
This causes 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.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Robin Murphy <robin.murphy@arm.com> --- arch/arm64/mm/dma-mapping.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index c566ec8..79b0882 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -848,7 +848,7 @@ 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); -- 2.6.4
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