From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: SIGSEGV with -smp 17+, and error handling around... Date: Wed, 24 Mar 2010 14:11:21 +0200 Message-ID: <4BAA0169.7000707@redhat.com> References: <4BA13794.9080401@msgid.tls.msk.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: KVM list To: Michael Tokarev Return-path: Received: from mx1.redhat.com ([209.132.183.28]:55150 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755906Ab0CXMLb (ORCPT ); Wed, 24 Mar 2010 08:11:31 -0400 In-Reply-To: <4BA13794.9080401@msgid.tls.msk.ru> Sender: kvm-owner@vger.kernel.org List-ID: On 03/17/2010 10:12 PM, Michael Tokarev wrote: > When run with -smp 17 or greather, kvm > fails like this: > > $ kvm -smp 17 > kvm_create_vcpu: Invalid argument > kvm_setup_mce FAILED: Invalid argument > KVM_SET_LAPIC failed > Segmentation fault > $ _ > > In qemu-kvm.c, the kvm_create_vcpu() routine > (which is used in a vcpu thread to set up > vcpu) is declared as void, i.e, no error > return. And the code that calls it blindly > assumes that it will never fail... > > But the first error message above is from kernel, > which - apparently - refuses to create 17th vCPU. > Hence we've a vcpu thread which is empty/dummy and > not even fully initialized... so it fails later > in the game. > > This all looks quite... raw, not polished ;) > > Can we somehow handle the (several possible) errors > in that (and other) places, and how we ever can act > on them? Abort? Warn the user and reduce the number > of vcpus accordingly (seems wrong, esp. if it were > some first vcpus or in the middle which failed)... > A patch from Alex fixing this was just committed. I'll apply it to the stable branch as well. -- error compiling committee.c: too many arguments to function