From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suravee Suthikulpanit Subject: Re: [PATCH] x86/ats: Disable Address Translation Services by default Date: Thu, 28 Aug 2014 05:07:12 -0500 Message-ID: <53FEFF50.8040605@amd.com> References: <1408550481-31464-1-git-send-email-andrew.cooper3@citrix.com> <53F7563C020000780002CB46@mail.emea.novell.com> <53FED55B.5030109@amd.com> <53FEF731020000780002E7A9@mail.emea.novell.com> <53FEE5BB.7000907@amd.com> <53FF04A8020000780002E8D8@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53FF04A8020000780002E8D8@mail.emea.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: Yang Z Zhang , Andrew Cooper , Kevin Tian , Aravind Gopalakrishnan , Xen-devel List-Id: xen-devel@lists.xenproject.org On 08/28/2014 03:30 AM, Jan Beulich wrote: >>>> On 28.08.14 at 10:18, wrote: >> On 08/28/2014 02:32 AM, Jan Beulich wrote: >>>>>> On 28.08.14 at 09:08, wrote: >>>> I have verified that PCI device pass-through works with ATS disabled. >>>> Although, could you please help described how "asynchronous queued >>>> invalidation support" supposed to work? >>> >>> Are asking about the abstract model, or the specific implementation? >>> The former is quite obvious is think (utilize the respective interrupt to >>> get notified of completions and suspend the execution in the current >>> context until then), >> >> So, what Andrew is saying is that the current implementation which uses >> the "synchronous wait for completion" is not safe? May be I'm not >> getting the whole picture here of how it is unsafe. > > It may be spinning for up to a second, and for ATS it would really > need to be spinning for up to 60 seconds (perhaps even 90, > depending on how to interpret the spec). > > Jan > Thanks for clarification. Acked-by: Suravee Suthikulpanit