On 15/02/15 19:03, Jan Kiszka wrote: > On 2015-02-15 19:01, Jan Kiszka wrote: >> On 2015-02-15 16:30, Marc Zyngier wrote: >>> On Sun, Feb 15 2015 at 3:07:50 pm GMT, Jan Kiszka >>> <jan.kiszka@xxxxxx> wrote: >>>> On 2015-02-15 15:59, Marc Zyngier wrote: >>>>> On Sun, Feb 15 2015 at 2:40:40 pm GMT, Jan Kiszka >>>>> <jan.kiszka@xxxxxx> wrote: >>>>>> On 2015-02-15 14:37, Marc Zyngier wrote: >>>>>>> On Sun, Feb 15 2015 at 8:53:30 am GMT, Jan Kiszka >>>>>>> <jan.kiszka@xxxxxx> wrote: >>>>>>>> I'm now throwing trace_printk at my broken KVM. Already >>>>>>>> found out that I get ARM_EXCEPTION_IRQ every few 10 µs. >>>>>>>> Not seeing any irq_* traces, though. Weird. >>>>>>> >>>>>>> This very much looks like a screaming interrupt. At such >>>>>>> a rate, no wonder your VM make much progress. Can you >>>>>>> find out which interrupt is screaming like this? Looking >>>>>>> at GICC_HPPIR should help, but you'll have to map the CPU >>>>>>> interface in HYP before being able to access it there. >>>>>> >>>>>> OK... let me figure this out. I had this suspect as well - >>>>>> the host gets a VM exit for each injected guest IRQ? >>>>> >>>>> Not exactly. There is a VM exit for each physical interrupt >>>>> that fires while the guest is running. Injecting an interrupt >>>>> also causes a VM exit, as we force the vcpu to reload its >>>>> context. >>>> >>>> Ah, GICC != GICV - you are referring to host-side pending IRQs. >>>> Any hints on how to get access to that register would >>>> accelerate the analysis (ARM KVM code is still new to me). >>> >>> Map the GICC region in HYP using create_hyp_io_mapping (see >>> vgic_v2_probe for an example of how we map GICH), and stash the >>> read of GICC_HPPIR before leaving HYP mode (and before saving the >>> guest timer). > >> Hacked on it until it started to work. The result delivered >> initially are 0x002 or 0x01e. Then, when the guest gets stuck, I >> have 0x01b most of the time (a few 0x01e arrive when there is a >> real host irq). The virtual timer on speed? > >> Wait, there is also early printk for ARM, but it was off in my >> guest! Turning it on confirms we have some problems here: > >> Architected timer frequency not available Division by zero in >> kernel. > >> When in emulation mode, I get: > >> Architected cp15 timer(s) running at 62.50MHz (virt). > >> Digging deeper. > > U-Boot didn't initialize CNTFRQ on cores 1..3. Fixing this, the guest > passes early boot reliably, now hangs much later (RCU stalls are > detected by the guest). Right, that explains a lot of things. Can you describe a bit more what you're seeing now? thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
