TrustZone: forcing instant switch from secure to normal world?

[David Goltzsche]

Hi Martin,

thanks for the help. When passing the physical IRQ number, it works!

David

On 08/03/2015 03:49 PM, Martin Stein wrote:
> Hi David,
> 
> Yes, you're right. I had the same problem when I received my first IRQ.
> This is what Linux commit [1] is for. It calls tzic_end_sw_irq at the
> end of event_interrupt in file [2]. Note that you have to call it with
> the physical IRQ number (in my case defined through the Genode config
> and read via SMC genode_block_irq) and not the virtual IRQ number, which
> is normally used in Linux (e.g. on request_irq).
> 
> [1] 0fa1c63 .handle multiple replies and end interrupt
> 
> [2] <LINUX>/drivers/block/genode_block.c
> 
> On 28.07.2015 15:03, David Goltzsche wrote:
>> Hi Martin,
>>
>> based on the commits you mentioned, I implemented a minimal kernel
>> module, which should receive the interrupts injected by genode.
>>
>> Overall it works: My Handler gets called when I trigger a software
>> interrupt in genode.
>>
>> However, the handler is called endlessly for a single interrupt. I
>> assume, i have to clear the interrupt somehow. I called
>> tzic_end_sw_irq(..) before returning from the handler.
>>
>> Here is my code: http://pastebin.com/NDBV6qYf
>>
>> Any Hints?
>>
>> David
>>
>> On 06/29/2015 12:05 PM, Martin Stein wrote:
>>> Hi David,
>>>
>>> On 29.06.2015 09:20, Stefan Kalkowski wrote:
>>>>> So, my approach would be using software interrupts which sould be routed
>>>>> to the normal world. I played around with the svc (supervisor call)
>>>>> instruction, but I don't know how to route this to the secure world.
>>>>
>>>> Indeed, this seems to be the most promising approach triggering a
>>>> software interrupt on the secure side, and handle it in the normal
>>>> world. Everything that needs to be done is marking a designated SPI (ARM
>>>> terminology for software-triggered IRQ) as a non-secure interrupt, and
>>>> delegate that interrupt to your kernel module within the guest OS.
>>>> Moreover, you will need to extend the VM session interface with the
>>>> ability to trigger that designated "TrustZone interrupt", as the
>>>> user-level VMM is not able to access the interrupt controller directly,
>>>> which has to be done by the kernel itself.
>>>
>>> On my working branches [1] I've implemented IRQ injection to provide a
>>> pseudo block device in a non-secure linux guest. Maybe this code gives
>>> you some good hints. Especially the linux commits [2] and the Genode
>>> commits [3] should be interesting. Please be aware that this code is
>>> still in progress and should not be considered as final solution.
>>>
>>> Don't hesitate to ask if you have further questions ;)
>>>
>>> Cheers,
>>> Martin
>>>
>>> [1]
>>> https://github.com/m-stein/genode/tree/1497_usb_armory_demo
>>> https://github.com/m-stein/linux/tree/1497_usb_armory_demo
>>>
>>> [2]
>>> 0fa1c63 .handle multiple replies and end interrupt
>>> 9ca75d0 .injected IRQ reaches the stub-block handler in linux
>>>
>>> [3]
>>> 08a3b09 .prototype of inject_vm_irq kernel call
>>> 2927f04 .Vm_session::inject_irq(unsigned irq)
>>> 42865c4 .injected IRQ reaches the stub-block handler in linux
>>>
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>>
> 
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-- 
M.Sc. David Goltzsche
Institute of Operating Systems and Computer Networks
Distributed Systems Group
TU Braunschweig

www: https://www.ibr.cs.tu-bs.de/users/goltzsch
mail: goltzsche at ...290...