Hi Zeng, On 31/01/2019 14:47, Zheng Xiang wrote: > Hi Marc, > > On 2019/1/29 13:42, Zheng Xiang wrote: >> On 2019/1/28 21:51, Marc Zyngier wrote: >>> On 28/01/2019 07:13, Zheng Xiang wrote: >>>> Hi Marc, >>>> >>>> Thanks for your review. >>>> >>>> On 2019/1/26 19:38, Marc Zyngier wrote: >>>>> Hi Zheng, >>>>> >>>>> On Sat, 26 Jan 2019 06:16:24 +0000, >>>>> Zheng Xiang <[email protected]> wrote: >>>>>> >>>>>> Currently each PCI device under a PCI Bridge shares the same device id >>>>>> and ITS device. Assume there are two PCI devices call its_msi_prepare >>>>>> concurrently and they are both going to find and create their ITS >>>>>> device. There is a chance that the later one couldn't find ITS device >>>>>> before the other one creating the ITS device. It will cause the later >>>>>> one to create a different ITS device even if they have the same >>>>>> device_id. >>>>> >>>>> Interesting finding. Is this something you've actually seen in practice >>>>> with two devices being probed in parallel? Or something that you found >>>>> by inspection? >>>> >>>> Yes, I find this problem after analyzing the reason of VM hung. At last, I >>>> find that the virtio-gpu cannot receive the MSI interrupts due to sharing >>>> a same event_id as virtio-serial. >>>> >>>> See https://lkml.org/lkml/2019/1/10/299 for the bug report. >>>> >>>> This problem can be reproducted with high probability by booting a Qemu/KVM >>>> VM with a virtio-serial controller and a virtio-gpu adding to a PCI Bridge >>>> and also adding some delay before creating ITS device. >>> >>> Fair enough. Do you mind sharing your QEMU command line? It'd be useful >>> if I could reproduce it here (and would give me a way to check that it >>> doesn't regress). >> > > Have you reproduced it with my QEMU command line? > > If so, should I send a V2 patch with your suggestion?
I've queued the following, much more complete patch: https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/irqchip-next&id=9791ec7df0e7b4d80706ccea8f24b6542f6059e9 Can you check that it works for you? I didn't manage to get the right timing conditions, but I also had issues getting virtio-gpu running on my TX2, so one might explain the other. Thanks, M. -- Jazz is not dead. It just smells funny...
