Re: [Xen-devel] [Patch RFC 00/13] VT-d Asynchronous Device-TLB Flush for ATS Device

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.09.15 at 11:46, <quan.xu@xxxxxxxxx> wrote:
>>> >>> On 21.09.15 at 16:51, < JBeulich@xxxxxxxx > wrote:
>>- Anything else?
> 
> 
> Just test the extreme case. The ATS specification mandates a timeout of 1 
> _minute_ for cache flush, even though it doesn't take so much time for cache 
> flush.
> In my design, if the Device-TLB is not completed, the domain's vCPUs are not 
> allowed entry guest mode (patch #7), otherwise, the logic is not correct.

Hmm, that would be a serious limitation, and I can't immediately
see a reason: Taking this with virtualization removed, I don't
think such an invalidation would stall a physical CPU for a whole
minute. Sadly I also can't immediately think of a solution, but I
guess first of all I'll have to take a look at the series (which
unfortunately may take a few days to get to).

Jan


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