Commit 7d835134 authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

iommu/arm-smmu: Make instance lookup robust 



Relying on the driver list was a cute idea for minimising the scope of
our SMMU device lookups, however it turns out to have a subtle flaw. The
SMMU device only gets added to that list after arm_smmu_device_probe()
returns success, so there's actually no way the iommu_device_register()
call from there could ever work as intended, even if it wasn't already
hampered by the fwspec setup not happening early enough.

Switch both arm_smmu_get_by_fwnode() implementations to use a platform
bus lookup instead, which *will* reliably work. Also make sure that we
don't register SMMUv2 instances until we've fully initialised them, to
avoid similar consequences of the lookup now finding a device with no
drvdata. Moving the error returns is also a perfect excuse to streamline
them with dev_err_probe() in the process.

Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/6d7ce1dc31873abdb75c895fb8bd2097cce098b4.1733406914.git.robin.murphy@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 9b640ae7

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

+2 −2
Original line number Diff line number Diff line
@@ -3351,8 +3351,8 @@ static struct platform_driver arm_smmu_driver; 
static

struct arm_smmu_device *arm_smmu_get_by_fwnode(struct fwnode_handle *fwnode)

{

	struct device *dev = driver_find_device_by_fwnode(&arm_smmu_driver.driver,

							  fwnode);

	struct device *dev = bus_find_device_by_fwnode(&platform_bus_type, fwnode);



	put_device(dev);

	return dev ? dev_get_drvdata(dev) : NULL;

}

drivers/iommu/arm/arm-smmu/arm-smmu.c

+13 −16
Original line number Diff line number Diff line
@@ -1411,8 +1411,8 @@ static bool arm_smmu_capable(struct device *dev, enum iommu_cap cap) 
static

struct arm_smmu_device *arm_smmu_get_by_fwnode(struct fwnode_handle *fwnode)

{

	struct device *dev = driver_find_device_by_fwnode(&arm_smmu_driver.driver,

							  fwnode);

	struct device *dev = bus_find_device_by_fwnode(&platform_bus_type, fwnode);



	put_device(dev);

	return dev ? dev_get_drvdata(dev) : NULL;

}
@@ -2227,29 +2227,26 @@ static int arm_smmu_device_probe(struct platform_device *pdev) 
					i, irq);

	}



	platform_set_drvdata(pdev, smmu);



	/* Check for RMRs and install bypass SMRs if any */

	arm_smmu_rmr_install_bypass_smr(smmu);



	arm_smmu_device_reset(smmu);

	arm_smmu_test_smr_masks(smmu);



	err = iommu_device_sysfs_add(&smmu->iommu, smmu->dev, NULL,

				     "smmu.%pa", &smmu->ioaddr);

	if (err) {

		dev_err(dev, "Failed to register iommu in sysfs\n");

		return err;

	}

	if (err)

		return dev_err_probe(dev, err, "Failed to register iommu in sysfs\n");



	err = iommu_device_register(&smmu->iommu, &arm_smmu_ops,

				    using_legacy_binding ? NULL : dev);

	if (err) {

		dev_err(dev, "Failed to register iommu\n");

		iommu_device_sysfs_remove(&smmu->iommu);

		return err;

		return dev_err_probe(dev, err, "Failed to register iommu\n");

	}



	platform_set_drvdata(pdev, smmu);



	/* Check for RMRs and install bypass SMRs if any */

	arm_smmu_rmr_install_bypass_smr(smmu);



	arm_smmu_device_reset(smmu);

	arm_smmu_test_smr_masks(smmu);



	/*

	 * We want to avoid touching dev->power.lock in fastpaths unless

	 * it's really going to do something useful - pm_runtime_enabled()