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Re: [Qemu-devel] virtio device error reporting best practice?
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] virtio device error reporting best practice? |
Date: |
Thu, 20 Mar 2014 07:39:57 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
Rusty Russell <address@hidden> writes:
> Markus Armbruster <address@hidden> writes:
>> Rusty Russell <address@hidden> writes:
>>> The litmus test: does *your* guest handle failures other than by giving
>>> up on the device? If so, sure, you need to have a sane error-reporting
>>> strategy.
>>
>> Err, isn't this a circular argument? No need for QEMU to report the
>> failure, because the guest won't handle it; no need to handle the
>> failure, because QEMU won't report it.
>>
>> What about this: would you make your guest handle failures if they were
>> reported?
>
> Perhaps I was unclear, that's what I meant.
>
>>>> The main reason I'm considering this stuff is for security reasons if
>>>> the guest asks for something really illegal or crazy what should the
>>>> expected behaviour of the host be? (at least secure I know that).
>>>
>>> If the guest userspace can do it, don't exit. If the kernel only, and
>>> it's should have known better, abort is OK.
>>>
>>> Sure that doesn't help much!
>>
>> Immediate exit() or abort() denies the guest the ability to degrade
>> service gracefully (disable the device, cry for help and try to hobble
>> on), or report its brokenness ungracefully (kernel panic, crash dump).
>> I doubt denying that is okay unless the device is so important that
>> without it you can't even hope to panic.
>
> Oh yes, I completely agree with you! But QEMU practice doesn't :)
Ah, then we're in violent agreement :)
Time to cease the practice. Will be hard as long as the code
is chock-full of bad examples.
- Re: [Qemu-devel] virtio device error reporting best practice?, (continued)
- Re: [Qemu-devel] virtio device error reporting best practice?, Gerd Hoffmann, 2014/03/17
- Re: [Qemu-devel] virtio device error reporting best practice?, Andreas Färber, 2014/03/17
- Re: [Qemu-devel] virtio device error reporting best practice?, Kevin Wolf, 2014/03/18
- Re: [Qemu-devel] virtio device error reporting best practice?, Richard W.M. Jones, 2014/03/17
- Re: [Qemu-devel] virtio device error reporting best practice?, Richard W.M. Jones, 2014/03/17
Re: [Qemu-devel] virtio device error reporting best practice?, Stefan Hajnoczi, 2014/03/26
Re: [Qemu-devel] virtio device error reporting best practice?, Gerd Hoffmann, 2014/03/17
Re: [Qemu-devel] virtio device error reporting best practice?, Rusty Russell, 2014/03/18
Re: [Qemu-devel] virtio device error reporting best practice?, Michael S. Tsirkin, 2014/03/20