Re: [PATCH 2/6] KVM: Add KVM_CAP_DIRTY_LOG_RING_ORDERED capability and config option

[Marc Zyngier <maz@kernel.org>]

On Sat, 24 Sep 2022 14:22:32 +0100,
Peter Xu <peterx@redhat.com> wrote:
> 
> On Sat, Sep 24, 2022 at 12:26:53PM +0100, Marc Zyngier wrote:
> > On Sat, 24 Sep 2022 09:51:39 +0100,
> > Marc Zyngier <maz@kernel.org> wrote:
> > > 
> > > I'm happy to bikeshed, but please spell it out for me. If we follow
> > > the current scheme, we need 3 configuration symbols (of which we
> > > already have one), and 2 capabilities (of which we already have one).
> 
> I hope it's not bikeshedding.  I normally don't comment on namings at all
> because many of them can be "bikeshedding" to me.  But this one is so
> special because it directly collides with KVM_GET_DIRTY_LOG, which is other
> method of dirty tracking.

Fair enough. I'm notoriously bad at sticking a name to things, so I'm
always happy to receive suggestions.

> 
> > > 
> > > Do you have any concrete proposal for those?
> > 
> > In order to make some forward progress, I've reworked the series[1]
> > with another proposal for those:
> > 
> > Config symbols:
> > 
> > - HAVE_KVM_DIRTY_RING:
> >   * mostly the same meaning as today
> >   * not directly selected by any architecture
> >   * doesn't expose any capability on its own
> > 
> > - HAVE_KVM_DIRTY_RING_TSO:
> >   * only for strongly ordered architectures
> >   * selects HAVE_KVM_DIRTY_RING
> >   * exposes KVM_CAP_DIRTY_LOG_RING
> >   * selected by x86
> > 
> > - HAVE_KVM_DIRTY_RING_ACQ_REL:
> >   * selects HAVE_KVM_DIRTY_RING
> >   * exposes KVM_CAP_DIRTY_LOG_RING_ACQ_REL
> >   * selected by arm64 and x86
> > 
> > Capabilities:
> > 
> > - KVM_CAP_DIRTY_LOG_RING: the good old x86-specific stuff, advertised
> >   when HAVE_KVM_DIRTY_RING_TSO is selected
> > 
> > - KVM_CAP_DIRTY_LOG_RING_ACQ_REL: the new acquire/release semantics,
> >   advertised when HAVE_KVM_DIRTY_RING_ACQ_REL is selected
> > 
> > This significantly reduces the churn and makes things slightly more
> > explicit.
> 
> This looks good to me, thanks.

OK, thanks for having a quick look. I'll repost this shortly, after
I'm done reviewing Gavin's series.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.
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