From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: arm: warning at virt/kvm/arm/vgic.c:1468 Date: Mon, 16 Feb 2015 08:57:50 +0000 Message-ID: <54E1B10E.8000402@arm.com> References: <54D714B9.6090106@web.de> <20150213044613.GA47577@lvm> <87k2zms4ub.fsf@linaro.org> <87iof6s3o7.fsf@linaro.org> <54E05E8A.5020109@web.de> <87wq3je1o4.fsf@why.wild-wind.fr.eu.org> <54E0AFE8.20202@web.de> <87oaovdxvb.fsf@why.wild-wind.fr.eu.org> <54E0B646.6030601@web.de> <87k2zjdwg4.fsf@why.wild-wind.fr.eu.org> <54E0DEE8.7020109@web.de> <54E0ED9C.1000208@web.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: =?UTF-8?B?QWxleCBCZW5uw6ll?= , Christoffer Dall , kvmarm , kvm , Paolo Bonzini , Wei Huang To: Jan Kiszka Return-path: Received: from foss.arm.com ([217.140.101.70]:51407 "EHLO usa-sjc-mx-foss1.foss.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752213AbbBPI5y (ORCPT ); Mon, 16 Feb 2015 03:57:54 -0500 In-Reply-To: <54E0ED9C.1000208@web.de> Sender: kvm-owner@vger.kernel.org List-ID: 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 >>> wrote: >>>> On 2015-02-15 15:59, Marc Zyngier wrote: >>>>> On Sun, Feb 15 2015 at 2:40:40 pm GMT, Jan Kiszka >>>>> wrote: >>>>>> On 2015-02-15 14:37, Marc Zyngier wrote: >>>>>>> On Sun, Feb 15 2015 at 8:53:30 am GMT, Jan Kiszka >>>>>>> wrote: >>>>>>>> I'm now throwing trace_printk at my broken KVM. Already >>>>>>>> found out that I get ARM_EXCEPTION_IRQ every few 10 =C2=B5s. >>>>>>>> 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 !=3D 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). >=20 >> 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? >=20 >> Wait, there is also early printk for ARM, but it was off in my >> guest! Turning it on confirms we have some problems here: >=20 >> Architected timer frequency not available Division by zero in >> kernel. >=20 >> When in emulation mode, I get: >=20 >> Architected cp15 timer(s) running at 62.50MHz (virt). >=20 >> Digging deeper. >=20 > 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. --=20 Jazz is not dead. It just smells funny...