Re: [PATCH] x86/ats: Disable Address Translation Services by default

[Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>]

On 08/28/2014 03:30 AM, Jan Beulich wrote:
>>>> On 28.08.14 at 10:18, <suravee.suthikulpanit@amd.com> wrote:
>> On 08/28/2014 02:32 AM, Jan Beulich wrote:
>>>>>> On 28.08.14 at 09:08, <suravee.suthikulpanit@amd.com> 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 <suravee.suthikulpanit@amd.com>