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From:   Andy Lutomirski <luto@kernel.org>
Date:   Mon, 13 May 2019 11:18:41 -0700
Message-ID: <CALCETrWUKZv=wdcnYjLrHDakamMBrJv48wp2XBxZsEmzuearRQ@mail.gmail.com>
Subject: Re: [RFC KVM 18/27] kvm/isolation: function to copy page table
 entries for percpu buffer
To:     Alexandre Chartre <alexandre.chartre@oracle.com>
Cc:     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>,
        Andrew Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        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>
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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.