Re: amd kdump failure with iommu=nopt

[Jerry Snitselaar]

On Thu May 14 20, Joerg Roedel wrote:
> On Thu, May 14, 2020 at 05:36:23PM +0200, Joerg Roedel wrote:
> > This commit also removes the deferred attach of the device to its new
> > domain. Does the attached diff fix the problem for you?
> > +static int __iommu_attach_device_no_defer(struct iommu_domain *domain,
> > +					  struct device *dev)
> > +{
> >  	if (unlikely(domain->ops->attach_dev == NULL))
> >  		return -ENODEV;
> >
> >  	ret = domain->ops->attach_dev(domain, dev);
> >  	if (!ret)
> >  		trace_attach_device_to_domain(dev);
> > +
> >  	return ret;
> >  }
>
> Sorry, this didn't compile, here is an updated version that actually
> compiles:
>
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 4050569188be..f54ebb964271 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1889,13 +1889,19 @@ void iommu_domain_free(struct iommu_domain *domain)
> }
> EXPORT_SYMBOL_GPL(iommu_domain_free);
>
> -static int __iommu_attach_device(struct iommu_domain *domain,
> -				 struct device *dev)
> +static bool __iommu_is_attach_deferred(struct iommu_domain *domain,
> +				       struct device *dev)
> +{
> +	if (!domain->ops->is_attach_deferred)
> +		return false;
> +
> +	return domain->ops->is_attach_deferred(domain, dev);
> +}
> +
> +static int __iommu_attach_device_no_defer(struct iommu_domain *domain,
> +					  struct device *dev)
> {
> 	int ret;
> -	if ((domain->ops->is_attach_deferred != NULL) &&
> -	    domain->ops->is_attach_deferred(domain, dev))
> -		return 0;
>
> 	if (unlikely(domain->ops->attach_dev == NULL))
> 		return -ENODEV;
> @@ -1903,9 +1909,19 @@ static int __iommu_attach_device(struct iommu_domain *domain,
> 	ret = domain->ops->attach_dev(domain, dev);
> 	if (!ret)
> 		trace_attach_device_to_domain(dev);
> +
> 	return ret;
> }
>
> +static int __iommu_attach_device(struct iommu_domain *domain,
> +				 struct device *dev)
> +{
> +	if (__iommu_is_attach_deferred(domain, dev))
> +		return 0;
> +
> +	return __iommu_attach_device_no_defer(domain, dev);
> +}
> +
> int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
> {
> 	struct iommu_group *group;
> @@ -2023,7 +2039,12 @@ EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev);
>  */
> struct iommu_domain *iommu_get_dma_domain(struct device *dev)
> {
> -	return dev->iommu_group->default_domain;
> +	struct iommu_domain *domain = dev->iommu_group->default_domain;
> +
> +	if (__iommu_is_attach_deferred(domain, dev))
> +		__iommu_attach_device_no_defer(domain, dev);
> +
> +	return domain;
> }
>
> /*
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Yes, that works.

Tested-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>