From: christoffer.dall@linaro.org (Christoffer Dall)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] KVM: ARM: Get rid of KVM_HPAGE_ defines
Date: Sun, 25 Aug 2013 17:46:16 -0700 [thread overview]
Message-ID: <20130826004616.GA13231@cbox> (raw)
In-Reply-To: <CAFEAcA9jcSby0JTZnEBW5Gwfn0SN770E0nSW3CSiOev16=kp5g@mail.gmail.com>
On Sun, Aug 25, 2013 at 04:18:02PM +0100, Peter Maydell wrote:
> On 25 August 2013 15:48, Gleb Natapov <gleb@redhat.com> wrote:
> > On Sun, Aug 25, 2013 at 03:29:17PM +0100, Peter Maydell wrote:
> >> Smiley noted, but this is pretty unlikely since it's not possible
> >> to lie to the guest about which mode it's in, so you can't make
> >> a guest think it's in Hyp mode.
> >>
> > I suspected this, but forgot most that I read about Hyp mode by now.
> > Need to refresh my memory ASAP. Is it impossible even with a lot of
> > emulation? Can guest detect that it is not in a Hyp mode without
> > trapping into hypervisor?
>
> Yes. The current mode is in the the low bits of the CPSR, which
> is readable without causing a trap. This is just the most obvious
> roadblock; I bet there are more. If you really had to run Hyp mode
> code in a VM you probably have to do it by having it all emulated
> via TCG.
>
Or through some highly paravirtualized nested virtualization solution if
that is ever relevant.
-Christoffer
WARNING: multiple messages have this Message-ID (diff)
From: Christoffer Dall <christoffer.dall@linaro.org>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Gleb Natapov <gleb@redhat.com>,
Patch Tracking <patches@linaro.org>,
"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>,
kvm-devel <kvm@vger.kernel.org>
Subject: Re: [PATCH 2/3] KVM: ARM: Get rid of KVM_HPAGE_ defines
Date: Sun, 25 Aug 2013 17:46:16 -0700 [thread overview]
Message-ID: <20130826004616.GA13231@cbox> (raw)
In-Reply-To: <CAFEAcA9jcSby0JTZnEBW5Gwfn0SN770E0nSW3CSiOev16=kp5g@mail.gmail.com>
On Sun, Aug 25, 2013 at 04:18:02PM +0100, Peter Maydell wrote:
> On 25 August 2013 15:48, Gleb Natapov <gleb@redhat.com> wrote:
> > On Sun, Aug 25, 2013 at 03:29:17PM +0100, Peter Maydell wrote:
> >> Smiley noted, but this is pretty unlikely since it's not possible
> >> to lie to the guest about which mode it's in, so you can't make
> >> a guest think it's in Hyp mode.
> >>
> > I suspected this, but forgot most that I read about Hyp mode by now.
> > Need to refresh my memory ASAP. Is it impossible even with a lot of
> > emulation? Can guest detect that it is not in a Hyp mode without
> > trapping into hypervisor?
>
> Yes. The current mode is in the the low bits of the CPSR, which
> is readable without causing a trap. This is just the most obvious
> roadblock; I bet there are more. If you really had to run Hyp mode
> code in a VM you probably have to do it by having it all emulated
> via TCG.
>
Or through some highly paravirtualized nested virtualization solution if
that is ever relevant.
-Christoffer
next prev parent reply other threads:[~2013-08-26 0:46 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-09 4:07 [PATCH 0/3] KVM/ARM Huge pages support Christoffer Dall
2013-08-09 4:07 ` Christoffer Dall
2013-08-09 4:07 ` [PATCH 1/3] KVM: Move gfn_to_index to x86 specific code Christoffer Dall
2013-08-09 4:07 ` Christoffer Dall
2013-08-09 4:07 ` [PATCH 2/3] KVM: ARM: Get rid of KVM_HPAGE_XXX defines Christoffer Dall
2013-08-09 4:07 ` Christoffer Dall
2013-08-09 4:07 ` [PATCH 3/3] KVM: ARM: Transparent huge pages and hugetlbfs support Christoffer Dall
2013-08-09 4:07 ` Christoffer Dall
2013-09-23 10:11 ` Marc Zyngier
2013-09-23 10:11 ` Marc Zyngier
2013-09-23 14:46 ` Marc Zyngier
2013-09-23 14:46 ` Marc Zyngier
2013-09-24 15:41 ` Steve Capper
2013-09-24 15:41 ` Steve Capper
2013-10-02 22:36 ` Christoffer Dall
2013-10-02 22:36 ` Christoffer Dall
2013-10-03 20:33 ` Christoffer Dall
2013-10-03 20:33 ` Christoffer Dall
2013-10-04 9:23 ` Marc Zyngier
2013-10-04 9:23 ` Marc Zyngier
2013-08-09 14:30 ` [PATCH 2/3] KVM: ARM: Get rid of KVM_HPAGE_ defines Christoffer Dall
2013-08-09 14:30 ` Christoffer Dall
2013-08-25 14:05 ` Gleb Natapov
2013-08-25 14:05 ` Gleb Natapov
2013-08-25 14:29 ` Peter Maydell
2013-08-25 14:29 ` Peter Maydell
2013-08-25 14:48 ` Gleb Natapov
2013-08-25 14:48 ` Gleb Natapov
2013-08-25 15:18 ` Peter Maydell
2013-08-25 15:18 ` Peter Maydell
2013-08-25 15:27 ` Alexander Graf
2013-08-25 15:27 ` Alexander Graf
2013-08-26 10:55 ` Gleb Natapov
2013-08-26 10:55 ` Gleb Natapov
2013-08-26 0:46 ` Christoffer Dall [this message]
2013-08-26 0:46 ` Christoffer Dall
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