Re: [PATCH v2.1] x86/retpoline: Fill return stack buffer on vmexit

[Peter Zijlstra]

On Thu, Jan 11, 2018 at 02:28:32PM +0000, David Woodhouse wrote:
> On Thu, 2018-01-11 at 08:20 -0600, Josh Poimboeuf wrote:
> > 
> > This seems weird.  I liked v1 a lot better.  What's the problem with
> > patching in the whole thing?
> > 
> > Also, if you go back to v1, it should be an easy objtool fix, just add
> > ANNOTATE_NOSPEC_ALTERNATIVE in front of it.
> 
> The objection was that I was patching in a fairly long set of
> instructions. I confess I don't actually know why that's a problem,

You get a giant string of NOPs, a single jmp should be faster.