From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: kernel bug in kvm_intel Date: Sun, 01 Nov 2009 13:31:04 +0200 Message-ID: <4AED7178.2060906@redhat.com> References: <4ACF9745.3050902@linux.vnet.ibm.com> <4AD16ACE.6040903@redhat.com> <1255372957.4883.49.camel@twinturbo.austin.ibm.com> <4AD4231F.6040608@redhat.com> <1255442640.4883.56.camel@twinturbo.austin.ibm.com> <4AD6061D.5070306@redhat.com> <1255637909.4883.129.camel@twinturbo.austin.ibm.com> <1256926052.4883.203.camel@twinturbo.austin.ibm.com> <4AEC5C24.9080506@redhat.com> <4AEC64FC.7070908@linux.vnet.ibm.com> <4AEC6699.6000202@redhat.com> <4AEC6821.7010801@redhat.com> <4AED5C3F.9050506@kernel.org> <4AED6100.6040804@redhat.com> <4AED66D0.20704@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Andrew Theurer , kvm@vger.kernel.org, Linux-kernel@vger.kernel.org To: Tejun Heo Return-path: In-Reply-To: <4AED66D0.20704@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 11/01/2009 12:45 PM, Tejun Heo wrote: > Hello, > > Avi Kivity wrote: > >> We get a page fault immediately (next instruction) after returning from >> the guest when running with oprofile. The page fault address does not >> match anything the instruction does, so presumably it is one of the >> accesses the processor performs in order to service an NMI (ordinary >> interrupts are masked; and the fact that it happens with oprofile >> strengthens this assumption). >> > Ah... okay, that's tricky but IIRC faults like that can be > distinguished from regular ones via processor state, right? > Not on x86. But given that the fault address is different from %rsp (which is what the instruction accesses) and %rip, there aren't many alternatives. >> Here is the code in question: >> >> >>> 3ae7: 75 05 jne 3aee >>> 3ae9: 0f 01 c2 vmlaunch >>> 3aec: eb 03 jmp 3af1 >>> 3aee: 0f 01 c3 vmresume >>> 3af1: 48 87 0c 24 xchg %rcx,(%rsp) >>> >> ^^^ fault, but not at (%rsp) >> > Can you please post the full oops (including kernel debug messages > during boot) or give me a pointer to the original message? http://www.mail-archive.com/kvm@vger.kernel.org/msg23458.html > Also, does > the faulting address coincide with any symbol? > No (at least, not in System.map). -- error compiling committee.c: too many arguments to function