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Date:   Tue, 14 May 2019 09:09:41 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     Alexandre Chartre <alexandre.chartre@oracle.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Radim Krcmar <rkrcmar@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        kvm list <kvm@vger.kernel.org>, X86 ML <x86@kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        jan.setjeeilers@oracle.com, Liran Alon <liran.alon@oracle.com>,
        Jonathan Adams <jwadams@google.com>
Subject: Re: [RFC KVM 18/27] kvm/isolation: function to copy page table
 entries for percpu buffer
Message-ID: <20190514070941.GE2589@hirez.programming.kicks-ass.net>
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 <CALCETrWUKZv=wdcnYjLrHDakamMBrJv48wp2XBxZsEmzuearRQ@mail.gmail.com>
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On Mon, May 13, 2019 at 11:18:41AM -0700, Andy Lutomirski wrote:
> On Mon, May 13, 2019 at 7:39 AM Alexandre Chartre
> <alexandre.chartre@oracle.com> wrote:
> >
> > pcpu_base_addr is already mapped to the KVM address space, but this
> > represents the first percpu chunk. To access a per-cpu buffer not
> > allocated in the first chunk, add a function which maps all cpu
> > buffers corresponding to that per-cpu buffer.
> >
> > Also add function to clear page table entries for a percpu buffer.
> >
> 
> This needs some kind of clarification so that readers can tell whether
> you're trying to map all percpu memory or just map a specific
> variable.  In either case, you're making a dubious assumption that
> percpu memory contains no secrets.

I'm thinking the per-cpu random pool is a secrit. IOW, it demonstrably
does contain secrits, invalidating that premise.