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RE: [Xen-devel] [PATCH] NextRIPS support for forthcoming AMD processors

  • To: "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Langsdorf, Mark" <mark.langsdorf@xxxxxxx>
  • Date: Wed, 15 Oct 2008 16:49:21 -0500
  • Cc:
  • Delivery-date: Wed, 15 Oct 2008 14:49:52 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AckvCpCpz0n8Npr9Ed2JPwAWy6hiGQABNg7A
  • Thread-topic: [Xen-devel] [PATCH] NextRIPS support for forthcoming AMD processors

> > This patch has been stress tested at AMD for three weeks of
> > continuous runtime and should not cause any regressions.
> The check of vmexit code in svm_nextrip_is_valid() could also
> perhaps be avoided? _get_instruction_length[_from_list]() is 
> used only in a very few cases, and in quite likely all those
> situations the nrip field would actually be valid. Have
> you checked that, or are there in fact some
> callers for whom nrip isn't guaranteed valid?

All current callers of get_instruction_length() are valid for
nextRIPS.  I'd prefer to leave the code check in so as to
future proof the code.  If someone adds another caller of
get_instruction_length, I wouldn't want to add an obscure
bug if NextRIPS isn't valid for that use.

I'll resubmit the patch without the disable feature.

-Mark Langsdorf
Operating System Research Center

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