Re: [PATCH 03/24] x86/paravirt: Annotate indirect calls

[Peter Zijlstra]

On Thu, Jan 25, 2018 at 10:02:05AM +0000, David Woodhouse wrote:
> On Tue, 2018-01-23 at 16:25 +0100, Peter Zijlstra wrote:
> > Paravirt emits indirect calls which get flagged by objtool retpoline
> > checks, annotate it away because all these indirect calls will be
> > patched out before we start userspace.
> 
> I've seen this asserted repeatedly but I've never truly convinced
> myself of it. Is this absolutely unconditionally true in every case,
> even when we're running as a guest and there are *actual* calls to be
> made? We turn them into direct calls, never leave them indirect?

That is my understanding; and when I worked on the paravirt spinlock
code and disassembled live guest code this seemed to have happend.

But let me go read the paravirt code again to make a stronger argument
in favour.