Re: [PATCH v6 1/4] KVM: arm64: Introduce cache maintenance callbacks for guest stage-2

[wangyanan (Y)]

On 2021/6/17 16:03, Marc Zyngier wrote:
> On Thu, 17 Jun 2021 07:48:29 +0100,
> "wangyanan (Y)" <wangyanan55@xxxxxxxxxx> wrote:
> > Hi Marc,
> >
> > On 2021/6/16 21:21, Marc Zyngier wrote:
> > > Hi Yanan,
> > >
> > > On Wed, 16 Jun 2021 10:51:57 +0100,
> > > Yanan Wang <wangyanan55@xxxxxxxxxx> wrote:
> > > > To prepare for performing guest CMOs in the fault handlers in pgtable.c,
> > > > introduce two cache maintenance callbacks in struct kvm_pgtable_mm_ops.
> > > >
> > > > The new callbacks are specific for guest stage-2, so they will only be
> > > > initialized in 'struct kvm_pgtable_mm_ops kvm_s2_mm_ops'.
> > > >
> > > > Signed-off-by: Yanan Wang <wangyanan55@xxxxxxxxxx>
> > > > ---
> > > >    arch/arm64/include/asm/kvm_pgtable.h | 7 +++++++
> > > >    1 file changed, 7 insertions(+)
> > > >
> > > > diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> > > > index c3674c47d48c..302eca32e0af 100644
> > > > --- a/arch/arm64/include/asm/kvm_pgtable.h
> > > > +++ b/arch/arm64/include/asm/kvm_pgtable.h
> > > > @@ -44,6 +44,11 @@ typedef u64 kvm_pte_t;
> > > >     *			in the current context.
> > > >     * @virt_to_phys:	Convert a virtual address mapped in the current context
> > > >     *			into a physical address.
> > > > + * @flush_dcache:	Clean data cache for a guest page address range before
> > > > + *			creating the corresponding stage-2 mapping.
> > > Please don't reintroduce the word 'flush'. We are really trying to
> > > move away from it as it doesn't describe what we want to do.
> > I agree with this. I intended to make the names short and laconic, but this
> > missed the information about the callback's actual behaviors.
> > > Here this
> > > should be 'clean_invalidate_dcache' which, despite being a mouthful,
> > > describe accurately what we expect it to do.
> > Sure, I will change the name as you suggested.
> > > The comment is also missing the invalidate part, and we shouldn't
> > > assume that this is only used for S2 mapping.
> > Ok, will refine the comment. I think something like"Clean and invalidate the
> > date cache for the specified memory address range" may be generic enough.
> > > > + * @flush_icache:	Invalidate instruction cache for a guest page address
> > > > + *			range before creating or updating the corresponding
> > > > + *			stage-2 mapping.
> > > Same thing here; this should be 'invalidate_icache', and the comment
> > > cleaned up.
> > Thanks, I will also correct this part.
> >
> > Besides the callback names and comments, is there anything else that still
> > needs some adjustment in the other three patches? :)
> It looks pretty good so far, much nicer than the previous versions.
>
> I have a small nit on the last patch, which should be dead easy to
> address. I'm currently running a bunch of tests, hopefully nothing bad
> will come out of it.
>
> If you respin it shortly, that nothing fails, and unless someone
> shouts, I'll queue it for -next.
It would be nice, thanks!
I will address the nit and respin the series soon.

Thanks,
Yanan
.
> Thanks,
>
> 	M.