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Re: [Xen-devel] [PATCH v2 1/2] x86/VPMU: return correct fixed PMC count

On 11/25/2015 10:31 AM, Jan Beulich wrote:

However, I just noticed that various control and status registers are
not available for v1. I wonder whether we should even support version 1
since we'd need to add whole lot of 'if (supported)' throughout the code
plus there are some assumptions about existence of IA32_PERF_GLOBAL_CTRL
so we'll need to add additional logic to handle that too. And it's not
clear to me if it's all worth it.
Indeed, let's not support v1 then for now and leave the exercise
to add all the if()s to whoever cares for such support.

And, in fact, I think we should drop model check in core2_vpmu_init() and only test for PMU version. Especially in light of XSA-163.

We could limit support to versions 2 and 3 only if we want to be on the safe side.

If people agree I'll send a patch (on Monday).


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