From: Gleb Natapov <gleb@redhat.com>
To: Arthur Chunqi Li <yzt356@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
SPA <infinite.questions@gmail.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: Correct way of tracking reads on given gfn ?
Date: Tue, 10 Sep 2013 09:08:39 +0300 [thread overview]
Message-ID: <20130910060838.GV17294@redhat.com> (raw)
In-Reply-To: <CABpY8MKa=bM9KkAgiGAqiKXfii-vHL++on518Dm2E_TVfBH6ew@mail.gmail.com>
On Tue, Sep 10, 2013 at 09:12:11AM +0800, Arthur Chunqi Li wrote:
> On Mon, Sep 9, 2013 at 8:29 PM, Gleb Natapov <gleb@redhat.com> wrote:
> > On Mon, Sep 09, 2013 at 12:53:02PM +0200, Paolo Bonzini wrote:
> >> Il 09/09/2013 12:22, SPA ha scritto:
> >> > Thanks Paolo.
> >> >
> >> > Is there a way where reads would trap ?
> >> >
> >> > I explored a bit on PM_PRESENT_MASK. Though its not READ bit, but a
> >> > PRESENT bit, it looks like it should generate traps on reads if this
> >> > bit is reset. From code, looks like rmap_write_protect() like function
> >> > I stated in previous mail should do. Would this approach work ? Are
> >> > there any glaring problems with this approach ?
> >>
> >> I cannot say right away. Another way could be to set reserved bits to
> >> generate EPT misconfigurations. See ept_set_mmio_spte_mask and
> >> is_mmio_spte.
> >>
> >> This would trap both reads and writes.
> >>
> > Dropping all sptes will also work, but trapping each read access will be dog slow. QEMU
> > emulation will be much faster.
> Hi Gleb,
> I'm interested in this topic, what do you mean by QEMU emulation? Do
> you mean the functions in arch/x86/kvm/emulate.c? In what scenario
> will KVM call these functions?
>
No, I mean don't use KVM at all.
--
Gleb.
prev parent reply other threads:[~2013-09-10 6:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 9:45 Correct way of tracking reads on given gfn ? Sunil
2013-09-09 10:08 ` Paolo Bonzini
2013-09-09 10:22 ` SPA
2013-09-09 10:53 ` Paolo Bonzini
2013-09-09 12:29 ` Gleb Natapov
2013-09-10 1:12 ` Arthur Chunqi Li
2013-09-10 6:08 ` Gleb Natapov [this message]
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