linux-kernel - Re: [PATCH v5 4/7] iommu/vt-d: Factoring out PASID set up helper function

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Date:   Thu, 4 May 2023 14:39:05 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Baolu Lu <baolu.lu@...ux.intel.com>
Cc:     "Tian, Kevin" <kevin.tian@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Joerg Roedel <joro@...tes.org>,
        "dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
        "vkoul@...nel.org" <vkoul@...nel.org>,
        Will Deacon <will@...nel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Liu, Yi L" <yi.l.liu@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Jiang, Dave" <dave.jiang@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Zanussi, Tom" <tom.zanussi@...el.com>,
        "Ranganathan, Narayan" <narayan.ranganathan@...el.com>,
        jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH v5 4/7] iommu/vt-d: Factoring out PASID set up helper
 function

Hi Baolu,

On Wed, 3 May 2023 14:37:16 +0800, Baolu Lu <baolu.lu@...ux.intel.com>
wrote:

> On 4/28/23 5:47 PM, Tian, Kevin wrote:
> >> From: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> >> Sent: Friday, April 28, 2023 1:50 AM
> >>
> >>
> >> +static int dmar_domain_attach_device_pasid(struct dmar_domain *domain,
> >> +					   struct intel_iommu *iommu,
> >> +					   struct device *dev,
> >> ioasid_t pasid) +{
> >> +	int ret;
> >> +
> >> +	/* PASID table is mandatory for a PCI device in scalable
> >> mode. */
> >> +	if (!sm_supported(iommu) && dev_is_real_dma_subdevice(dev))
> >> +		return -EOPNOTSUPP;  
> > 
> > "&&" should be "||"
> >   
> 
> Also should return success instead if this is a RID case. Perhaps,
> 
> 	if (!sm_supported(iommu) || dev_is_real_dma_subdevice(dev))
> 		return pasid == RID2PASID ? 0 : -EOPNOTSUPP;
> 
Yeah,  I think this is better.  will do.

I was hoping not to treat RIDPASID special here. The caller of this
function does the check if that is RIDPASID but code is duplicated.

Thanks,

Jacob