linux-kernel - Re: [PATCH v7 02/11] KVM: pfncache: add a mark-dirty helper

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Message-ID: <ZUV9LMM8FhQD8ycD@google.com>
Date:   Fri, 3 Nov 2023 16:07:24 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     paul@....org
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Paul Durrant <pdurrant@...zon.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        David Woodhouse <dwmw2@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: Re: [PATCH v7 02/11] KVM: pfncache: add a mark-dirty helper

On Thu, Nov 02, 2023, Paul Durrant wrote:
> On 31/10/2023 23:28, Sean Christopherson wrote:
> > On Mon, Oct 02, 2023, Paul Durrant wrote:
> > > diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c
> > > index 0f36acdf577f..b68ed7fa56a2 100644
> > > --- a/virt/kvm/pfncache.c
> > > +++ b/virt/kvm/pfncache.c
> > > @@ -386,6 +386,12 @@ int kvm_gpc_activate(struct gfn_to_pfn_cache *gpc, gpa_t gpa, unsigned long len)
> > >   }
> > >   EXPORT_SYMBOL_GPL(kvm_gpc_activate);
> > > +void kvm_gpc_mark_dirty(struct gfn_to_pfn_cache *gpc)
> > > +{
> > 
> > If there's actually a reason to call mark_page_dirty_in_slot() while holding @gpc's
> > lock, then this should have a lockdep.  If there's no good reason, then don't move
> > the invocation.
> > 
> > > +	mark_page_dirty_in_slot(gpc->kvm, gpc->memslot, gpc->gpa >> PAGE_SHIFT);
> > > +}
> > > +EXPORT_SYMBOL_GPL(kvm_gpc_mark_dirty);
> > 
> > This doesn't need to be exported.  Hrm, none of the exports in this file are
> > necessary, they likely all got added when we were thinking this stuff would be
> > used for nVMX.  I think we should remove them, not because I'm worried about
> > sub-modules doing bad things, but just because we should avoid polluting exported
> > symbols as much as possible.
> 
> That in a separate clean-up patch too, I assume?

Yes, but feel free to punt that one or post it as a standalone patch.  For this
series, please just don't add more exports unless they're actually used in the
series.