Re: [RFC PATCH v2 20/32] iommu: Add APIs to get preserved state of a device

[Baolu Lu]

On 12/3/25 07:02, Samiullah Khawaja wrote:
> The preserved state of the device needs to be fetched at various places
> during liveupdate. The added API can also be used to check if a device
> is preserved or not. The API is only used during shutdown and after
> liveupdate so no locking needed.
>
> Signed-off-by: Samiullah Khawaja<skhawaja@xxxxxxxxxx>
> ---
>   include/linux/iommu-lu.h | 67 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 67 insertions(+)
>
> diff --git a/include/linux/iommu-lu.h b/include/linux/iommu-lu.h
> index 95375530b7be..08a659de8553 100644
> --- a/include/linux/iommu-lu.h
> +++ b/include/linux/iommu-lu.h
> @@ -8,9 +8,76 @@
>   #ifndef _LINUX_IOMMU_LU_H
>   #define _LINUX_IOMMU_LU_H
>   
> +#include <linux/device.h>
> +#include <linux/iommu.h>
>   #include <linux/liveupdate.h>
>   #include <linux/kho/abi/iommu.h>
>   
> +#ifdef CONFIG_LIVEUPDATE
> +static inline void *dev_iommu_preserved_state(struct device *dev)
> +{
> +	struct device_ser *ser;
> +
> +	ser = dev->iommu->device_ser;

This might cause "NULL pointer dereference" issue if the device is not
iommu probed.

	if (!dev->iommu)
		return NULL;
	ser = dev->iommu->device_ser;

> +	if (ser && !ser->obj.incoming)
> +		return ser;
> +
> +	return NULL;
> +}

Thanks,
baolu