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Re: [Qemu-devel] Coding style for errors
From: |
Lluís Vilanova |
Subject: |
Re: [Qemu-devel] Coding style for errors |
Date: |
Fri, 23 Oct 2015 19:34:50 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Stefan Hajnoczi writes:
> On Thu, Oct 22, 2015 at 03:30:34PM +0200, Lluís Vilanova wrote:
>> Markus Armbruster writes:
>>
>> > Lluís Vilanova <address@hidden> writes:
>> [...]
>> >> So, is there any agreement on what should be used? If so, could that
>> >> please be
>> >> added to CODING_STYLE?
>>
>> > I think HACKING would be a better fit.
>>
>> What about this? (at the end of HACKING) Feel free to add references to other
>> functions you think are important. I'll send a patch once we agree on the
>> text.
>>
>> Cheers,
>> Lluis
>>
>>
>> 7. Error reporting
> Guest-triggerable errors should not terminate QEMU. There are plently
> of examples where this is violated today but there are good reasons to
> stop doing it.
> Denial of service cases:
> 1. If a guest userspace application is somehow able to trigger a QEMU
> abort, then an unprivileged guest application is able to bring down
> the whole VM.
> 2. If nested virtualization is used, it's possible that a nested guest
> can kill its parent, and thereby also kill its sibling VMs.
> 3. abort(3) is heavyweight if crash reporting/coredumps are enabled. A
> broken/malicious guest that keeps triggering abort(3) can be a big
> nuisance that consumes memory, disk, and CPU resources.
> Emulated hardware should behave the same way that physical hardware
> behaves. This may mean that the device becomes non-operational (ignores
> or fails new requests) until the next hard or soft reset.
I'm not sure how this should be translated into the form of error-reporting
guidelines.
Thanks,
Lluis
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