Re: [PATCH 1/3] x86: add support for computing the instruction length

["Mihai Donțu" <mdontu@bitdefender.com>]

On Tuesday 09 September 2014 17:25:58 Jan Beulich wrote:
> >>> On 09.09.14 at 18:01, <mdontu@bitdefender.com> wrote:
> > I've opted to send a new mail so I can remove Masami from CC, as he's
> > probably not interested in the rest of the conversation.
> > 
> > Right now we have two patches which work around x86/emulator
> > limitations:
> > 
> >  * one computes the instruction length;
> >  * the other uses single stepping to jump over unsupported instructions;
> > 
> > Adding support for the complete x86(_64) instruction set to the
> > existent emulator in Xen would make those two unneeded and while I
> > would like to try my hand at it, I'm not sure the effort would be pay
> > off. Not to mention that I would very much like to _somehow_ catch the
> > 4.5 deadline. I wonder if it's possible to do this in iterations: take
> > this (or a decent derivation of it) in, while Răzvan and I work on doing
> > a better work for 4.6. Am I pushing it? :-)
> 
> Personally I don't think this makes sense to push for 4.5, but in the
> end it'll be Konrad's call. We already have enough other half-way
> reviewed patch series that need finalizing, so I don't think this series
> (which was posted just once many weeks ago) is a candidate.
> Furthermore I'm rather unconvinced of this being code useful to
> other than just your product.

I don't know how to dispel this belief, which I think comes from the
fact that currently we appear to be the only security vendor to open
source at least a part of our work on using hypervisors as a security
tool (at least in this fashion). Our end goal is to create a generic
interface which anyone can use to do what we are proposing and put the
effort into building a technology on top of it so that we can say for
certain what such an interface should offer. If either my or Răzvan's
suggestions/needs look specific, it's only because no one else outside
Bitdefender spoke out (and I know of a few who are silently following
this thread).

> And finally, we had (with other submitters) some bad experience in the
> past taking what they promised they would clean up later.

Fair enough.

-- 
Mihai Donțu

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