Re: Errors on MMIO read access on VM suspend / resume operations

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 01/16/2011 09:43 AM, Avi Kivity wrote:
> On 01/14/2011 09:27 PM, Stefan Berger wrote:
>>
>>>
>>> Can you sprinkle some printfs() arount kvm_run (in qemu-kvm.c) to 
>>> verify this?
>>>
>> Here's what I did:
>>
>>
>> interrupt exit requested
>
> It appears from this you're using qemu.git.  Please try qemu-kvm.git, 
> where the code appears to be correct.
>
Cc'ing qemu-devel now. For reference, here the initial problem description:

http://www.spinics.net/lists/kvm/msg48274.html

I didn't know there was another tree...

I have seen now a couple of suspends-while-reading with patches applied 
to the qemu-kvm.git tree and indeed, when run with the same host kernel 
and VM I do not see the debugging dumps due to double-reads that I would 
have anticipated seeing by now. Now what? Can this be easily fixed in 
the other Qemu tree as well?

One thing I'd like to mention is that I have seen what I think are 
interrupt stalls when running my tests inside the qemu-kvm.git tree 
version and not suspending at all. A some point the interrupt counter in 
the guest kernel does not increase anymore even though I see the device 
model raising the IRQ and lowering it. The same tests run literally 
forever in the qemu.git tree version of Qemu.

Regards,
    Stefan