Trustzone with virt_qemu_arm_v8a

Tue Feb 28 14:28:14 CET 2023

Hello,

On Tue, Feb 28, 2023 at 06:26:06PM +0530, Divya Sharma wrote:
> To be more specific we want to create an app/program on Linux/Android and
> for cryptographic work, we want to switch to a trusted os, Genode.
> so we need to work on 2 things
> 1) switching between Normal os to secure os and vice versa
> 2) set up Linux/android on top of genode.

Okay. Please be aware, that you have to partition the devices to be
used by either side, only TrustZone-aware devices can get "shared"
resp. used by both sides, e.g., the CPU and interrup-controller.

> 
> please suggest something for 2nd option.

The steps necessary for this use-case I've already sketched in my last
response. Please read that carefully. If you have more specific
implementation and design questions regarding our software stack,
please feel free to ask.

Regards
Stefan

> 
> Regards
> Divya
> 
> 
> On Mon, Feb 27, 2023 at 4:45 PM Stefan Kalkowski <
> stefan.kalkowski at genode-labs.com> wrote:
> 
> > Hello Divya,
> >
> > On Mon, Feb 27, 2023 at 02:53:43PM +0530, Divya Sharma wrote:
> > > Dear Genodians,
> > >
> > > I hope this message finds you well. I am writing to follow up on our
> > > previous discussion regarding running kernels in secure mode using QEMU.
> > >
> > > As per your suggestion, we have investigated the use of QEMU for this
> > > purpose and found that it does support the required kernels. However, we
> > > require further guidance on setting up an exception vector for the EL3.
> > > Could you kindly provide us with the necessary steps to accomplish this
> > > task?
> > >
> >
> > This goes _far_ beyond the scope of an easy to answer "How to..."
> > question.
> >
> > My first counter question would be: what do you want to achieve?
> > What is your goal: do you want different fully functional OSes on both
> > sides: secure world and normal world, or "just" some library OS
> > functionality on the secure side for doing for instance some
> > cryptographic work? Is Genode running on both sides, or what is
> > running in the normal world?
> >
> > If you only want to "play" with the current possibilities of the
> > Genode framework only, this goes far beyond this scope. You would need
> > to develop certain functionalities not yet implemented for ARMv8. In
> > that case, much more knowledge about your envisioned system is needed.
> >
> > > Additionally, we are interested in running a simple program similar to
> > the
> > > one demonstrated in the IMX demo. Could you please suggest any relevant
> > > documents or threads that could assist us in achieving this objective?
> >
> > I don't know which "simple program" you mean actually? The only
> > visible TrustZone examples for i.MX53 I'm aware of are Linux or
> > Android running in the normal world, and Genode's base-hw kernel,
> > some drivers and a kind of TrustZone VMM running in the secure
> > world. This is actually no simple scenario at all.
> >
> > If you want to re-produce this scenario, you have to:
> >
> > * Analyze functionality and security-wise, which system registers have
> >   to be saved / restored by the secure-monitor on ARMv8
> > * Implement (in assembler) a world-switch routine from the
> >   normal-to-secure world (this is the exception vector), and
> >   vice-versa
> > * Setup the secure-monitor mode, e.g. by setting the exception
> >   vector's address in EL3 mode
> > * Re-write or extend the TrustZone VMM to handle ARMv8
> >
> > Regards
> > Stefan
> >
> > >
> > > Thank you for your time and assistance.
> > >
> > > Sincerely,
> > >
> > > Divya
> > >
> > > On Wed, Feb 22, 2023 at 2:30 PM Stefan Kalkowski <
> > > stefan.kalkowski at genode-labs.com> wrote:
> > >
> > > > Hello Devashish,
> > > >
> > > > in its currently used form on ARMv8: if Genode's own kernel variant
> > > > "base-hw" gets booted into TrustZone's secure mode at all, it leaves
> > > > it without doing any additional setup into the normal world resp.
> > > > directly into EL2 hypervisor mode to prepare that.
> > > >
> > > > With other words, without modifications you can't use the secure world
> > > > right now. On most platforms this is actually already in use by ARM's
> > > > Trusted Firmware (ATF), which implements things like multi-processor
> > > > wakeup, suspend etc., so we can't make use of it without replacing the
> > > > whole ATF.
> > > >
> > > > In general it is however possible to do so, but you'll need to do
> > > > several in-depth modifications to make that work. First you need to
> > > > find out whether on Qemu the kernel gets started in secure mode. If
> > > > yes you would need at least to setup an exception vector for the EL3
> > > > secure-monitor mode, so that you handle for instance SMC-calls.
> > > > Probably you'll need to setup the MMU for the EL3 mode.
> > > > To sum it up it is some serious work to do. If you are interested in
> > > > exploring that, please have a look into the current CPU and
> > exception-level
> > > > (EL) setup in file:
> > > > repos/base-hw/src/bootstrap/spec/arm_64/cortex_a53_mmu.cc
> > > > That would be a good starting point to hook in.
> > > >
> > > > Regards
> > > > Stefan
> > > >
> > > > On Wed, Feb 22, 2023 at 01:40:13PM +0530, Devashish Dewangan cs21m017
> > > > wrote:
> > > > > Dear Genodians,
> > > > > I am working with virt_qemu_arm_v8a, and I read the extensive
> > > > documentation
> > > > > on how Genode has experimented with the Trustzone of ARM. I want to
> > > > explore
> > > > > the Trustzone and run an application in the secure mode, but I
> > wanted to
> > > > > know if it is possible to do with virt_qemu_arm.
> > > > >
> > > > > --
> > > > > Regards,
> > > > > Devashish Dewangan
> > > > > CS21M017
> > > >
> > > > > _______________________________________________
> > > > > Genode users mailing list
> > > > > users at lists.genode.org
> > > > > https://lists.genode.org/listinfo/users
> > > >
> > > >
> > > > --
> > > > Stefan Kalkowski
> > > > Genode labs
> > > >
> > > > https://github.com/skalk | https://genode.org
> > > >
> > > > _______________________________________________
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> > > > users at lists.genode.org
> > > > https://lists.genode.org/listinfo/users
> > > >
> >
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> >
> >
> > --
> > Stefan Kalkowski
> > Genode labs
> >
> > https://github.com/skalk | https://genode.org
> >
> > _______________________________________________
> > Genode users mailing list
> > users at lists.genode.org
> > https://lists.genode.org/listinfo/users
> >

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-- 
Stefan Kalkowski
Genode labs

https://github.com/skalk | https://genode.org