Re: Re: [RFC] RAS(Part II)--MCA enalbing in XEN

[Frank van der Linden <Frank.Vanderlinden@Sun.COM>]

Christoph Egger wrote:
> On Wednesday 25 February 2009 03:25:12 Jiang, Yunhong wrote:
>
>> So, Frank/Egger, can I assume followed are consensus currently?
>>
>> 1) MCE is handled by Xen HV totally, while guest's vMCE handler will only
>> works for itself.
>> 2) Xen present a virtual #MC to guest through MSR access  
>> emulation.(Xen will do the translation if needed).
>> 3) Guest's unmodified 
>> MCE handler will handle the vMCE injected.
>> 4) Dom0 will get all log/telemetry through hypercall.
>> 5) The action taken by xen will be passed to dom0 through the telemetry
>> mechanism.
> 
> Mostly. Regarding 2) I want like to discuss first how to handle errors
> impacting multiple contiguous physical pages which are non-contigous
> in guest physical space.
> 
> And I also want to discuss about how to do recovery actions requiring
> PCI access. One example for this is
> Shanghai's "L3 Cache Index Disable"-Feature.
> Xen delegates PCI config space to Dom0 and
> via PCI passthrough partly to DomU.
> That means, if registers in PCI config space are independently
> accessable by Xen, Dom0 and/or DomU, they can interfere with each other.
> Therefore, we need to
> a) clearly define who handles what and
> b) define some rules based on a)
> c) discuss how to handle Dom0/DomU going wild
>     and break the rules defined in b)

I also agree on the approach in principle, but would like to see these 
points addressed. For non-contiguous pages, I suppose Xen could deliver 
multiple #vMCEs to the guest, split into contiguous parts. The vmce code 
seems to be set up to be able to do this.

As for the Shanghai feature: Christoph, are there any documents 
available on that feature? What kind of errors are delivered 
(corrected/correctable)?

- Frank