On 12/03/18 02:33, Yang, Shunyong wrote: > Hi, Marc, > > On Sun, 2018-03-11 at 12:17 +0000, Marc Zyngier wrote: >> On Sun, 11 Mar 2018 01:55:08 +0000 >> Christoffer Dall <cdall@xxxxxxxxxx> wrote: >> >>> >>> On Sat, Mar 10, 2018 at 12:20 PM, Marc Zyngier <marc.zyngier@xxxxxx >>> m> wrote: >>>> >>>> On Fri, 09 Mar 2018 21:36:12 +0000, >>>> Christoffer Dall wrote: >>>>> >>>>> >>>>> On Thu, Mar 08, 2018 at 05:28:44PM +0000, Marc Zyngier wrote: >>>>>> >>>>>> I'd be more confident if we did forbid P+A for such >>>>>> interrupts >>>>>> altogether, as they really feel like another kind of HW >>>>>> interrupt. >>>>> How about a slightly bigger hammer: Can we avoid doing P+A for >>>>> level >>>>> interrupts completely? I don't think that really makes much >>>>> sense, and >>>>> I think we simply everything if we just come back out and >>>>> resample the >>>>> line. For an edge, something like a network card, there's a >>>>> potential >>>>> performance win to appending a new pending state, but I doubt >>>>> that this >>>>> is the case for level interrupts. >>>> I started implementing the same thing yesterday. Somehow, it >>>> feels >>>> slightly better to have the same flow for all level interrupts, >>>> including the timer, and we only use the MI on EOI as a way to >>>> trigger >>>> the next state of injection. Still testing, but looking good so >>>> far. >>>> >>>> I'm still puzzled that we have this level-but-not-quite behaviour >>>> for >>>> VFIO interrupts. At some point, it is going to bite us badly. >>>> >>> Where is the departure from level-triggered behavior with VFIO? As >>> far as I can tell, the GIC flow of the interrupts will be just a >>> level >>> interrupt, >> The GIC is fine, I believe. What is not exactly fine is the >> signalling >> from the device, which will never be dropped until the EOI has been >> detected. >> >>> >>> but we just need to make sure the resamplefd mechanism is >>> supported for both types of interrupts. Whether or not that's a >>> decent mechanism seems orthogonal to me, but that's a discussion >>> for >>> another day I think. >> Given that VFIO is built around this mechanism, I don't think we have >> a >> choice but to support it. Anyway, I came up with the following patch, >> which I tested on Seattle with mtty. It also survived my usual >> hammering of cyclictest, hackbench and bulk VM installs. >> >> Shunyong, could you please give it a go? >> >> Thanks, >> >> M. >> > > I have tested the patch. It works on QDF2400 platform > and kvm_notify_acked_irq() is called when state is idle. Thanks a lot for testing. > > BTW, I have following questions when I was debugging the issue. > Coud you please give me some help? > 1)what does "mi" mean in gic code? such as lr_signals_eoi_mi(); MI stands for Maintenance Interrupts. Life is too short to write that all the time ;-) > 2)In some __hyp_text code where printk() will cause "HYP panic:", such > as in __kvm_vcpu_run(). How can I output debug information? You can't. None of the kernel is mapped at EL2 on pre-VHE hardware. You'll need to find indirect ways of outputting information (store data in memory, and output it once you're back to EL1). Thanks again, M. -- Jazz is not dead. It just smells funny... _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
