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: Sun, 15 Feb 2015 14:59:20 +0000 Message-ID: <87oaovdxvb.fsf@why.wild-wind.fr.eu.org> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <54E0AFE8.20202@web.de> (Jan Kiszka's message of "Sun, 15 Feb 2015 14:40:40 +0000") Sender: kvm-owner@vger.kernel.org To: Jan Kiszka Cc: Alex =?utf-8?Q?Benn=C3=A9e?= , Christoffer Dall , kvmarm , kvm , Paolo Bonzini , Wei Huang List-Id: kvmarm@lists.cs.columbia.edu 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 t= hat I >>> get ARM_EXCEPTION_IRQ every few 10 =C2=B5s. Not seeing any irq_* tr= aces, >>> though. Weird. >>=20 >> 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 h= ave >> to map the CPU interface in HYP before being able to access it there= =2E > > OK... let me figure this out. I had this suspect as well - the host g= ets > 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. > BTW, I also tried with in-kernel GIC disabled (in the kernel config), > but I guess that's pointless. Linux seems to be stuck on a > non-functional architectural timer then, right? Yes. Useful for bringup, but nothing more. >>=20 >> Do you have an form of power-management on this system? > > Just killed every config that has PM for FREQ in its name, but that > makes no difference. I still wonder if the 4+1 design on the K1 is not playing tricks behind our back. Having talked to Ian Campbell earlier this week, he also can'= t manage to run guests in Xen on this platform, so there's something rather fishy here. M. --=20 Without deviation from the norm, progress is not possible.