Re: [Xen-devel] [PATCH] iommu/quirk: disable shared EPT for Sandybridge and earlier processors.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.11.15 at 11:27, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 26/11/15 08:45, Jan Beulich wrote:
>>>>> On 25.11.15 at 16:58, <malcolm.crossley@xxxxxxxxxx> wrote:
>>> On 25/11/15 15:38, Jan Beulich wrote:
>>>>>>> On 25.11.15 at 16:13, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>>> On 25/11/15 10:49, Jan Beulich wrote:
>>>>>> And finally I'm not fully convinced using CPU model info to deduce
>>>>>> chipset behavior is entirely correct (albeit perhaps in practice it'll
>>>>>> be fine except maybe when running Xen itself virtualized).
>>>>> What else would you suggest? I can't think of any better identifying
>>>>> information.
>>>> Chipset IDs / revisions?
>>> In this case the IOMMU is integrated into the Sandybridge-EP processor 
>>> itself.
>> Which doesn't preclude it to be identified via PCI device ID - after all
>> there are dozens of processor integrated PCI devices. Looking at
>> one of my systems,
>>
>> 00:05.0 System peripheral [0880]: Intel Corporation Sandy Bridge Address 
> Map, VTd_Misc, System Management [8086:3c28] (rev 07)
>> 80:05.0 System peripheral [0880]: Intel Corporation Sandy Bridge Address 
> Map, VTd_Misc, System Management [8086:3c28] (rev 07)
>>
>> could be a candidate (we already key a quirk on this device in
>> pci_vtd_quirk()).
> 
> These are fine for server variants, but not for desktop variants, both
> of which we have seen in use.

And I gave them only as an example that keying off of PCI IDs
would be possible. A complete list would of course need to be
compiled (but I think we could simply derive it from the list of IDs
we already deal with in quirks.c).

Jan


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