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

[Glauber Costa]

On Fri, Apr 18, 2008 at 1:27 PM, Avi Kivity <address@hidden> wrote:
>
> 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.
>
Yes, I did.

Basic problem is that I basically could not find this information
handy until we were deep in the stack, right before calling the update
mapping functions. I turned out preferring this option. I can,
however, take a fresh look at that.

-- 
Glauber Costa.
"Free as in Freedom"
http://glommer.net

"The less confident you are, the more serious you have to act."