Re: [PATCH 07/10] acpi: Do not return struct iommu_ops from acpi_iommu_configure_id()

[Moritz Fischer <moritzf@google.com>]

On Tue, Nov 28, 2023 at 08:48:03PM -0400, Jason Gunthorpe wrote:
> Nothing needs this pointer. Return a normal error code with the usual
> IOMMU semantic that ENODEV means 'there is no IOMMU driver'.

> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
> Tested-by: Hector Martin <marcan@marcan.st>
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
>   drivers/acpi/scan.c | 29 +++++++++++++++++------------
>   1 file changed, 17 insertions(+), 12 deletions(-)

> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 444a0b3c72f2d8..340ba720c72129 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1562,8 +1562,7 @@ static inline const struct iommu_ops  
> *acpi_iommu_fwspec_ops(struct device *dev)
>   	return fwspec ? fwspec->ops : NULL;
>   }

> -static const struct iommu_ops *acpi_iommu_configure_id(struct device  
> *dev,
> -						       const u32 *id_in)
> +static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
>   {
>   	int err;
>   	const struct iommu_ops *ops;
> @@ -1577,7 +1576,7 @@ static const struct iommu_ops  
> *acpi_iommu_configure_id(struct device *dev,
>   	ops = acpi_iommu_fwspec_ops(dev);
>   	if (ops) {
>   		mutex_unlock(&iommu_probe_device_lock);
> -		return ops;
> +		return 0;
>   	}

>   	err = iort_iommu_configure_id(dev, id_in);
> @@ -1594,12 +1593,14 @@ static const struct iommu_ops  
> *acpi_iommu_configure_id(struct device *dev,

>   	/* Ignore all other errors apart from EPROBE_DEFER */
>   	if (err == -EPROBE_DEFER) {
> -		return ERR_PTR(err);
> +		return err;
>   	} else if (err) {
>   		dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
> -		return NULL;
> +		return -ENODEV;
>   	}
> -	return acpi_iommu_fwspec_ops(dev);
> +	if (!acpi_iommu_fwspec_ops(dev))
> +		return -ENODEV;
> +	return 0;
>   }

>   #else /* !CONFIG_IOMMU_API */
> @@ -1611,10 +1612,9 @@ int acpi_iommu_fwspec_init(struct device *dev, u32  
> id,
>   	return -ENODEV;
>   }

> -static const struct iommu_ops *acpi_iommu_configure_id(struct device  
> *dev,
> -						       const u32 *id_in)
> +static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
>   {
> -	return NULL;
> +	return -ENODEV;
>   }

>   #endif /* !CONFIG_IOMMU_API */
> @@ -1628,7 +1628,7 @@ static const struct iommu_ops  
> *acpi_iommu_configure_id(struct device *dev,
>   int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr,
>   			  const u32 *input_id)
>   {
> -	const struct iommu_ops *iommu;
> +	int ret;

>   	if (attr == DEV_DMA_NOT_SUPPORTED) {
>   		set_dma_ops(dev, &dma_dummy_ops);
> @@ -1637,10 +1637,15 @@ int acpi_dma_configure_id(struct device *dev,  
> enum dev_dma_attr attr,

>   	acpi_arch_dma_setup(dev);

> -	iommu = acpi_iommu_configure_id(dev, input_id);
> -	if (PTR_ERR(iommu) == -EPROBE_DEFER)
> +	ret = acpi_iommu_configure_id(dev, input_id);
> +	if (ret == -EPROBE_DEFER)
>   		return -EPROBE_DEFER;

> +	/*
> +	 * Historically this routine doesn't fail driver probing due to errors
> +	 * in acpi_iommu_configure_id()
> +	 */
> +
>   	arch_setup_dma_ops(dev, 0, U64_MAX, attr == DEV_DMA_COHERENT);

>   	return 0;
> --
> 2.42.0


Reviewed-by: Moritz Fischer <moritzf@google.com>

Cheers,
Moritz