linux-kernel - Re: [PATCH v5 04/13] KVM: Introduce a new guest mapping API

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Message-ID: <1548439773.17444.16.camel@amazon.de>
Date:   Fri, 25 Jan 2019 18:09:33 +0000
From:   "Raslan, KarimAllah" <karahmed@...zon.de>
To:     "konrad.wilk@...cle.com" <konrad.wilk@...cle.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
Subject: Re: [PATCH v5 04/13] KVM: Introduce a new guest mapping API

On Wed, 2019-01-23 at 12:50 -0500, Konrad Rzeszutek Wilk wrote:
> > 
> > +	if (dirty)
> > +		kvm_release_pfn_dirty(map->pfn);
> > +	else
> > +		kvm_release_pfn_clean(map->pfn);
> > +	map->hva = NULL;
> 
> I keep on having this gnawing feeling that we MUST set map->page to
> NULL.
> 
> That is I can see how it is not needed if you are using 'map' and
> 'unmap' together - for that we are good. But what I am worried is that
> some one unmaps it .. and instead of checking map->hva they end up
> checking map->page and think the page is mapped.
> 
> Would you be OK adding that extra statement just as a fail-safe
> mechanism in case someones misues the APIs?

Good point, will do.



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