linux-kernel - Re: [PATCH v3 10/21] KVM: arm64: Enable forcing page-level stage-2 mappings

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Message-ID: <CA+EHjTwamSQ+msUUnuCi6c_hw5TzDy-7dSxLxEnGmA4T4uhw_Q@mail.gmail.com>
Date:   Tue, 3 Aug 2021 12:43:30 +0200
From:   Fuad Tabba <tabba@...gle.com>
To:     Quentin Perret <qperret@...gle.com>
Cc:     maz@...nel.org, james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, ardb@...nel.org, qwandor@...gle.com,
        dbrazdil@...gle.com, kernel-team@...roid.com
Subject: Re: [PATCH v3 10/21] KVM: arm64: Enable forcing page-level stage-2 mappings

Hi Quentin,

> > > +static bool stage2_block_mapping_allowed(u64 addr, u64 end, u32 level,
> > > +                                        struct stage2_map_data *data)
> > > +{
> > > +       if (data->force_pte && (level < (KVM_PGTABLE_MAX_LEVELS - 1)))
> > > +               return false;
> >
> > I'm not sure I understand why checking the level is necessary. Can
> > there be block mapping at the last possible level?
>
> That's probably just a matter of naming, but this function is in fact
> called at every level, just like kvm_block_mapping_supported() was
> before. And we rely on it returning true at the last level, so I need to
> do that check here.
>
> Maybe renaming this stage2_leaf_mapping_allowed() would clarify?

Yes it would.

Thanks,
/fuad