[Qemu-devel] Re: [kvm-devel] [PATCH 0/3] Qemu crashes with pci passthrough

[Avi Kivity <avi@qumranet.com>]

Glauber de Oliveira Costa wrote:
> Hi, 
>
> I've got some qemu crashes while trying to passthrough an ide device
> to a kvm guest. After some investigation, it turned out that 
> register_ioport_{read/write} will abort on errors instead of returning
> a meaningful error.
>
> However, even if we do return an error, the asynchronous nature of pci
> config space mapping updates makes it a little bit hard to treat.
>
> This series of patches basically treats errors in the mapping functions in
> the pci layer. If anything goes wrong, we unregister the pci device, unmapping
> any mappings that happened to be sucessfull already.
>
> After these patches are applied, a lot of warnings appears. And, you know,
> everytime there is a warning, god kills a kitten. But I'm not planning on
> touching the other pieces of qemu code for this until we set up (or not) in
> this solution
>
> Comments are very welcome, specially from qemu folks (since it is a bit invasive)
>
>   

Have you considered, instead of rolling back the changes you already 
made before the failure, to have a function which checks if an ioport 
registration will be successful?  This may simplify the code.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.