Received-SPF: pass (google.com: domain of linux-kernel+bounces-138964-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Wed, 10 Apr 2024 09:19:55 -0700
From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Baolu Lu <baolu.lu@linux.intel.com>, "iommu@lists.linux.dev"
 <iommu@lists.linux.dev>, "Liu, Yi L" <yi.l.liu@intel.com>, Joerg Roedel
 <joro@8bytes.org>, Will Deacon <will@kernel.org>, Robin Murphy
 <robin.murphy@arm.com>, "linux-kernel@vger.kernel.org"
 <linux-kernel@vger.kernel.org>, jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH 2/2] iommu/vt-d: Remove caching mode check before devtlb
 flush
Message-ID: <20240410091955.5c00e411@jacob-builder>
In-Reply-To: <BN9PR11MB52763F42ED6719E6D03D0D308C062@BN9PR11MB5276.namprd11.prod.outlook.com>
References: <20240407144232.190355-1-baolu.lu@linux.intel.com>
	<20240407144232.190355-2-baolu.lu@linux.intel.com>
	<20240408140329.6290377f@jacob-builder>
	<aff42b8f-b757-4422-9ebe-741a4b894b6c@linux.intel.com>
	<20240409103146.0d155e45@jacob-builder>
	<BN9PR11MB52763F42ED6719E6D03D0D308C062@BN9PR11MB5276.namprd11.prod.outlook.com>
Organization: OTC
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit

Hi Kevin,

On Wed, 10 Apr 2024 00:32:06 +0000, "Tian, Kevin" <kevin.tian@intel.com>
wrote:

> > From: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Sent: Wednesday, April 10, 2024 1:32 AM
> > 
> > If the guest uses SL page tables in vIOMMU, we don;t expose ATS to the
> > guest. So ATS is not relevant here, does't matter map or unmap.
> >   
> 
> ATS is orthogonal to SL vs. FL. Where is this restriction coming from?
For practical purposes, what would be the usage to have SL in the guest and
ATS enabled. i.e. shadowing SL but directly expose ATS? 

Thanks,

Jacob