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From: "Raj, Ashok" <ashok.raj@intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "sathyanarayanan.kuppuswamy@linux.intel.com" 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	"bhelgaas@google.com" <bhelgaas@google.com>,
	"joro@8bytes.org" <joro@8bytes.org>,
	"dwmw2@infradead.org" <dwmw2@infradead.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Busch, Keith" <keith.busch@intel.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>
Subject: Re: [PATCH v2 2/2] iommu/vt-d: Enable PASID only if device expects PASID  in PRG Response.
Date: Wed, 13 Feb 2019 10:10:46 -0800	[thread overview]
Message-ID: <20190213181046.GA16999@araj-mobl1.jf.intel.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19C93AD90@SHSMSX104.ccr.corp.intel.com>

On Wed, Feb 13, 2019 at 12:26:33AM -0800, Tian, Kevin wrote:
> > 
> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index 1457f931218e..af2e4a011787 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -1399,7 +1399,8 @@ static void iommu_enable_dev_iotlb(struct
> > device_domain_info *info)
> >  	   undefined. So always enable PASID support on devices which
> >  	   have it, even if we can't yet know if we're ever going to
> >  	   use it. */
> > -	if (info->pasid_supported && !pci_enable_pasid(pdev, info-
> > >pasid_supported & ~1))
> > +	if (info->pasid_supported && pci_prg_resp_pasid_required(pdev)
> > &&
> > +	    !pci_enable_pasid(pdev, info->pasid_supported & ~1))
> >  		info->pasid_enabled = 1;
> 
> Above logic looks problematic. As Dave commented in another thread,
> PRI and PASID are orthogonal capabilities. Especially with introduction
> of VT-d scalable mode, PASID will be used alone even w/o PRI...
> 
> Why not doing the check when PRI is actually enabled? At that point
> you can fail the request if above condition is false. 
> 

That makes sense. 

  reply	other threads:[~2019-02-13 18:10 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 21:50 [PATCH v2 0/2] Add PGR response PASID requirement check in Intel IOMMU sathyanarayanan.kuppuswamy
2019-02-11 21:50 ` [PATCH v2 1/2] PCI/ATS: Add pci_prg_resp_pasid_required() interface sathyanarayanan.kuppuswamy
2019-02-13 19:49   ` Bjorn Helgaas
2019-02-11 21:50 ` [PATCH v2 2/2] iommu/vt-d: Enable PASID only if device expects PASID in PRG Response sathyanarayanan.kuppuswamy
2019-02-13  8:26   ` Tian, Kevin
2019-02-13 18:10     ` Raj, Ashok [this message]
2019-02-13 18:19     ` sathyanarayanan kuppuswamy

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