This is a note to let you know that I've just added the patch titled xen/grant-dma-iommu: Implement a dummy probe_device() callback to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xen-grant-dma-iommu-implement-a-dummy-probe_device-c.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit ba99064a7d3a70a15ef4ec39def27dbc2995a703 Author: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> Date: Wed Feb 8 17:36:49 2023 +0200 xen/grant-dma-iommu: Implement a dummy probe_device() callback [ Upstream commit 2062f9fb6445451b189595e295765c69f43bc12e ] Update stub IOMMU driver (which main purpose is to reuse generic IOMMU device-tree bindings by Xen grant DMA-mapping layer on Arm) according to the recent changes done in the following commit 57365a04c921 ("iommu: Move bus setup to IOMMU device registration"). With probe_device() callback being called during IOMMU device registration, the uninitialized callback just leads to the "kernel NULL pointer dereference" issue during boot. Fix that by adding a dummy callback. Looks like the release_device() callback is not mandatory to be implemented as IOMMU framework makes sure that callback is initialized before dereferencing. Reported-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Fixes: 57365a04c921 ("iommu: Move bus setup to IOMMU device registration") Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> Tested-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230208153649.3604857-1-olekstysh@xxxxxxxxx Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/xen/grant-dma-iommu.c b/drivers/xen/grant-dma-iommu.c index 16b8bc0c0b33d..6a9fe02c6bfcc 100644 --- a/drivers/xen/grant-dma-iommu.c +++ b/drivers/xen/grant-dma-iommu.c @@ -16,8 +16,15 @@ struct grant_dma_iommu_device { struct iommu_device iommu; }; -/* Nothing is really needed here */ -static const struct iommu_ops grant_dma_iommu_ops; +static struct iommu_device *grant_dma_iommu_probe_device(struct device *dev) +{ + return ERR_PTR(-ENODEV); +} + +/* Nothing is really needed here except a dummy probe_device callback */ +static const struct iommu_ops grant_dma_iommu_ops = { + .probe_device = grant_dma_iommu_probe_device, +}; static const struct of_device_id grant_dma_iommu_of_match[] = { { .compatible = "xen,grant-dma" },