RE: [Xen-devel] mce_wrmsr() and (at least) HVM guests

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> 04.01.10 09:31 >>>
>>>And also another potential issue raised out. For example, guest has
>>>clear one bit in MCn_CTL while physically it is enabled. If a error
>>>corresponding to this bit really happen, at least we should not inject
>>>a vMCE to guest. We will either kill the guest, or let the guest
>>>continues, depends on the error type .
>>
>>Yes, this would make sense, albeit it seems overkill to me - there
>>shouldn't really be disagreement in how specific models get handled.
>>Instead, perhaps an unprivileged guest should be permitted to write
>>zero bits wherever the underlying real register has them clear (as
>>read back from hardware, not as written by Xen or dom0).
>
>What do you mean of "write zero bits wherever the underlying real
>register has them clear"?

Writing e.g. all 1s into any of these registers doesn't mean you'd read
back all 1s. Hence, writing zero into read-only (always zero) bits should
be permitted as well as writing zero into bits that dom0 cleared
explicitly.

Jan


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