On Wed, 2 Dec 2015 16:34:56 -0600
Andrew Jones <[email protected]> wrote:
> On Fri, Nov 27, 2015 at 06:50:04PM +0000, Marc Zyngier wrote:
> > KVM so far relies on code patching, and is likely to use it more
> > in the future. The main issue is that our alternative system works
> > at the instruction level, while we'd like to have alternatives at
> > the function level.
>
> How about setting static-keys at hyp init time?
That was an option I looked at. And while static keys would work to some
extent, they also have some nasty side effects:
- They create both a fast and a slow path. We don't want that - both
path should be equally fast, or at least have as little overhead as
possible
- We do need code patching for some assembly code, and using static
keys on top creates a parallel mechanism that makes it hard to
follow/debug/maintain.
You can view this alternative function call as a slightly different
kind of static keys - one that can give you the capability to handle
function calls instead of just jumping over code sequences. Both have
their own merits.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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