linux-kernel - Re: [PATCH v4 11/12] iommu: Per-domain I/O page fault handling

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Date:   Thu, 28 Apr 2022 15:57:16 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 11/12] iommu: Per-domain I/O page fault handling

On Thu, Apr 21, 2022 at 01:21:20PM +0800, Lu Baolu wrote:
>  static void iopf_handle_group(struct work_struct *work)
>  {
>  	struct iopf_group *group;
> @@ -134,12 +78,23 @@ static void iopf_handle_group(struct work_struct *work)
>  	group = container_of(work, struct iopf_group, work);
>  
>  	list_for_each_entry_safe(iopf, next, &group->faults, list) {
> +		struct iommu_domain *domain;
> +
> +		domain = iommu_get_domain_for_dev_pasid_async(group->dev,
> +				iopf->fault.prm.pasid);

Reading the PCIe spec again (v6.0 10.4.1.1 PASID Usage), all faults within
the group have the same PASID so we could move the domain fetch out of the
loop. It does deviate from the old behavior, though, so we could change
it later.

Thanks,
Jean

> +		if (!domain || !domain->iopf_handler)
> +			status = IOMMU_PAGE_RESP_INVALID;
> +
>  		/*
>  		 * For the moment, errors are sticky: don't handle subsequent
>  		 * faults in the group if there is an error.
>  		 */
>  		if (status == IOMMU_PAGE_RESP_SUCCESS)
> -			status = iopf_handle_single(iopf);
> +			status = domain->iopf_handler(&iopf->fault,
> +						      domain->fault_data);
> +
> +		if (domain)
> +			iommu_domain_put_async(domain);
>  
>  		if (!(iopf->fault.prm.flags &
>  		      IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))