iommu/rockchip: prevent iommus dead loop when two masters share one IOMMU

BugLink: https://bugs.launchpad.net/bugs/2122072

commit 62e062a29ad5133f67c20b333ba0a952a99161ae upstream.

When two masters share an IOMMU, calling ops->of_xlate during
the second master's driver init may overwrite iommu->domain set
by the first. This causes the check if (iommu->domain == domain)
in rk_iommu_attach_device() to fail, resulting in the same
iommu->node being added twice to &rk_domain->iommus, which can
lead to an infinite loop in subsequent &rk_domain->iommus operations.

Cc: <stable@vger.kernel.org>
Fixes: 25c2325 ("iommu/rockchip: Add missing set_platform_dma_ops callback")
Signed-off-by: Simon Xue <xxm@rock-chips.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20250623020018.584802-1-xxm@rock-chips.com
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Noah Wager <noah.wager@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: Simon Xue

drivers/iommu/rockchip-iommu.c

@@ -1155,7 +1155,6 @@ static int rk_iommu_of_xlate(struct device *dev,
 	iommu_dev = of_find_device_by_node(args->np);
 
 	data->iommu = platform_get_drvdata(iommu_dev);
-	data->iommu->domain = &rk_identity_domain;
 	dev_iommu_priv_set(dev, data);
 
 	platform_device_put(iommu_dev);
@@ -1193,6 +1192,8 @@ static int rk_iommu_probe(struct platform_device *pdev)
 	if (!iommu)
 		return -ENOMEM;
 
+	iommu->domain = &rk_identity_domain;
+
 	platform_set_drvdata(pdev, iommu);
 	iommu->dev = dev;
 	iommu->num_mmu = 0;