Re: [PATCH v2 5/8] iommu: Add PASID support for DMA mapping API users

From: Jason Gunthorpe <jgg@nvidia.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: iommu@lists.linux-foundation.org,
	LKML <linux-kernel@vger.kernel.org>,
	Joerg Roedel <joro@8bytes.org>,
	Christoph Hellwig <hch@infradead.org>,
	Lu Baolu <baolu.lu@linux.intel.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Jacob Pan <jacob.jun.pan@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	"Zanussi, Tom" <tom.zanussi@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	"Tian, Kevin" <kevin.tian@intel.com>, Yi Liu <yi.l.liu@intel.com>
Subject: Re: [PATCH v2 5/8] iommu: Add PASID support for DMA mapping API users
Date: Tue, 15 Mar 2022 20:05:49 -0300	[thread overview]
Message-ID: <20220315230549.GP11336@nvidia.com> (raw)
In-Reply-To: <20220315093810.4b4c5ebf@jacob-builder>

On Tue, Mar 15, 2022 at 09:38:10AM -0700, Jacob Pan wrote:
> > > +int iommu_enable_pasid_dma(struct device *dev, ioasid_t *pasid)
> > > +{
> > > +	struct iommu_domain *dom;
> > > +	ioasid_t id, max;
> > > +	int ret;
> > > +
> > > +	dom = iommu_get_domain_for_dev(dev);
> > > +	if (!dom || !dom->ops || !dom->ops->attach_dev_pasid)
> > > +		return -ENODEV;  
> > 
> > Given the purpose of this API I think it should assert that the device
> > has the DMA API in-use using the machinery from the other series.
> > 
> > ie this should not be used to clone non-DMA API iommu_domains..
> > 
> Let me try to confirm the specific here. I should check domain type and
> rejects all others except IOMMU_DOMAIN_DMA type, right? Should also allow
> IOMMU_DOMAIN_IDENTITY.
> 
> That makes sense.

That is one way, the other is to check the new group data that Lu's
patch added.

Jason