On 2011-01-24 19:27, Stefan Berger wrote: > On 01/18/2011 03:53 AM, Jan Kiszka wrote: >> On 2011-01-18 04:03, Stefan Berger wrote: >>> 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? >> Please give this a try: >> >> git://git.kiszka.org/qemu-kvm.git queues/kvm-upstream >> >> I bet (& hope) "kvm: Unconditionally reenter kernel after IO exits" >> fixes the issue for you. If other problems pop up with that tree, also >> try resetting to that particular commit. >> >> I'm currently trying to shake all those hidden or forgotten bug fixes >> out of qemu-kvm and port them upstream. Most of those subtle differences >> should hopefully soon be history. >> > I did the same test as I did with Avi's tree and haven't seen the > consequences of possible double-reads. So, I would say that you should > upstream those patches... > > I searched for the text you mention above using 'gitk' but couldn't find > a patch with that headline in your tree. There were others that seem to > be related: > > Gleb Natapov: "do not enter vcpu again if it was stopped during IO" Err, I don't think you checked out queues/kvm-upstream. I bet you just ran my master branch which is a version of qemu-kvm's master. Am I right? :) >>> 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. >> What about qemu-kmv and -no-kvm-irqchip? > That seems to be necessary for both trees, yours and the one Avi pointed > me to. If applied, then I did not see the interrupt problem. And the fact that you were able to call qemu from my tree with -no-kvm-irqchip just underlines my assumption: that switch is refused by upstream. Please retry with the latest kvm-upstream queue. Besides that, this other bug you may see in the in-kernel IRQ path - how can we reproduce it? Jan
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