Messages in this thread | | | Date | Tue, 3 Jul 2012 16:50:41 +0200 | From | Christoph Egger <> | Subject | Re: [Xen-devel] [xen vMCE RFC V0.2] xen vMCE design |
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On 07/03/12 15:26, Luck, Tony wrote:
>> I'm not convinced of the need, and would prefer aiming at a >> shared implementation unless issues arise that make this >> impossible. > > It does sound odd. Yes, Intel and AMD have differences around CMCI ... but we are never > going to send a CMCI to a guest (there is no point, it can't do anything useful with the > information, it may do something pointlessly stupid like stop using a guest physical page). > The only reason I suggested making MCG_CAP pretend that CMCI was supported was a > small optimization ... if a Linux guest sees that CMCI is supported, it will not poll the machine > check banks looking for corrected errors.
Are you talking about PV or HVM guest?
For HVM guests yes it makes sense to disable CMCI in MCG_CAP for both AMD and Intel.
PV guests never read MCE MSRs directly. They install a trap handler and use the hypercall to fetch the error telemetry. The xen interface is common to both AMD and Intel - it's basically just an array of bytes. The first bytes tell you how you can cast and interpret the bytes. That *content* is specific to AMD or Intel.
How much logic can be shared is almost a matter of software design and not hardware design.
Christoph
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