From mboxrd@z Thu Jan 1 00:00:00 1970 From: sathyanarayanan kuppuswamy Subject: Re: [PATCH v1 1/1] iommu/vt-d: Enable PRI only if the device enables PASID. Date: Thu, 7 Feb 2019 13:30:24 -0800 Message-ID: References: <142748f6a00153f9926fe2a9dc30cf3cd89164cd.1549408090.git.sathyanarayanan.kuppuswamy@linux.intel.com> <0faf4f6a5bbd8cbee84aa78c40ab15216c2b8f0e.camel@infradead.org> <20190207210936.GH103220@otc-nc-03> <9393b9b2c15564ee84b627a73fb34bd17ebe4a7f.camel@infradead.org> Reply-To: sathyanarayanan.kuppuswamy@linux.intel.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <9393b9b2c15564ee84b627a73fb34bd17ebe4a7f.camel@infradead.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: David Woodhouse , "Raj, Ashok" Cc: joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Jacob Pan List-Id: iommu@lists.linux-foundation.org On 2/7/19 1:15 PM, David Woodhouse wrote: > On Thu, 2019-02-07 at 13:09 -0800, Raj, Ashok wrote: >> You are right.. they are completely orthogonal. We just don't have >> a way to handle the page-requests for request without PASID's. >> >> There are some of the vIOMMU work to pass the PRI to who owns >> the device, and we can certainly relax it then. This is just to reflect >> what support exists today. FWIW, even the native driver maybe be able >> to resolve this if supported. > As things stand, if a device makes a PRI request without a PASID, it'll > get told that we didn't manage to bring the page in for it. Which is > true. > > What's the actual problem being fixed by this patch? Since the request is going to fail any way why go through the process of enabling it ? Once the functionality (PRI without PASID) is supported, then they can revert this patch. Just we are trying to expose whats currently supported clearly. > Yes, we're going > to want to hook up a way to pass the PRI to the right place... but why > add *another* thing that's just going to have to be fixed, by reverting > this patch? > -- Sathyanarayanan Kuppuswamy Linux kernel developer