[PATCH 2/3] KVM: ARM: Get rid of KVM_HPAGE_ defines
agraf at suse.de
Sun Aug 25 11:27:14 EDT 2013
On 25.08.2013, at 16:18, Peter Maydell wrote:
> On 25 August 2013 15:48, Gleb Natapov <gleb at 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 in an in-kernel instruction emulator that we have lying around anyways. For kvm-in-kvm that should be good enough, as we only need to execute a few instructions in HYP mode.
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