Re: [PATCH v1 09/10] iommu/vt-d: Refactor dmar_insert_one_dev_info()

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

Hi BaoLu,

On Mon,  7 Feb 2022 14:41:41 +0800, Lu Baolu <baolu.lu@linux.intel.com>
wrote:

>  
> -	if (dev && domain_context_mapping(domain, dev)) {
> -		dev_err(dev, "Domain context map failed\n");
> -		dmar_remove_one_dev_info(dev);
> -		return NULL;
> -	}
> +	/* Setup the context entry for device: */
> +	ret = domain_context_mapping(domain, dev);
> +	if (ret)
> +		goto setup_context_err;
>  
> -	return domain;
> +	info->domain = domain;
> +	list_add_rcu(&info->link, &domain->devices);
> +
There seems to be an ordering problem. We need to do list_add_rcu()
*before*  domain_context_mapping(). Otherwise, while doing context mapping
the search for dev IOTLB support in iommu_support_dev_iotlb() will fail.
Then ATS capable device context will not have DTE bit set. The result is
DMAR unrecoverable fault while doing DMA.


Thanks,

Jacob