linux-kernel - Re: [PATCH v5 3/9] iommu: Add attachment handle to struct iopf

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Message-ID: <21ffbcc7-1103-4481-af14-5ee8856b9625@linux.intel.com>
Date: Fri, 10 May 2024 11:14:20 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: baolu.lu@...ux.intel.com, Kevin Tian <kevin.tian@...el.com>,
 Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>,
 Nicolin Chen <nicolinc@...dia.com>, Yi Liu <yi.l.liu@...el.com>,
 Jacob Pan <jacob.jun.pan@...ux.intel.com>,
 Joel Granados <j.granados@...sung.com>, iommu@...ts.linux.dev,
 virtualization@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/9] iommu: Add attachment handle to struct iopf_group

On 5/8/24 8:04 AM, Jason Gunthorpe wrote:
> On Tue, Apr 30, 2024 at 10:57:04PM +0800, Lu Baolu wrote:
>> @@ -206,8 +197,11 @@ void iommu_report_device_fault(struct device *dev, struct iopf_fault *evt)
>>   	if (group == &abort_group)
>>   		goto err_abort;
>>   
>> -	group->domain = get_domain_for_iopf(dev, fault);
>> -	if (!group->domain)
>> +	if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) ||
>> +	    get_attach_handle_for_iopf(dev, fault->prm.pasid, group))
>> +		get_attach_handle_for_iopf(dev, IOMMU_NO_PASID, group);
> That seems a bit weird looking?

Agreed.

> get_attach_handle_for_iopf(dev,
>     (fault->prm.flags &
>     IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) ? fault->prm.pasid : IOMMU_NO_PASID,
>     group);

The logic here is that it tries the PASID domain and if it doesn't
exist, then tries the RID domain as well. I explained this in the commit
message:

"
.. if the pasid table of a device is wholly managed by user space,
there is no domain attached to the PASID of the device ...
"

Perhaps I can improve it like this,

	int rc = -EINVAL;
	...
	if (fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)
		rc = get_attach_handle_for_iopf(dev, fault->prm.pasid, group);
	if (rc)
		rc = get_attach_handle_for_iopf(dev, IOMMU_NO_PASID, group);

	if (rc || !group->attach_handle->domain->iopf_handler)
		goto err_abort;

Best regards,
baolu