From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Richard W.M. Jones" Subject: Re: kvm [2087]: load/store instruction decoding not implemented Date: Tue, 24 Feb 2015 15:09:11 +0000 Message-ID: <20150224150911.GQ11603@redhat.com> References: <20150224115935.GA26241@redhat.com> <20150224122925.GL11603@redhat.com> <20150224124710.GB21364@cbox> <54EC78D1.3030703@arm.com> <20150224134533.GM11603@redhat.com> <54EC8654.1060905@arm.com> <20150224143608.GO11603@redhat.com> <54EC8DE6.8000105@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9077D4677D for ; Tue, 24 Feb 2015 10:03:42 -0500 (EST) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DwtjWJ1Sxalz for ; Tue, 24 Feb 2015 10:03:36 -0500 (EST) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id D68EC4673D for ; Tue, 24 Feb 2015 10:03:35 -0500 (EST) Content-Disposition: inline In-Reply-To: <54EC8DE6.8000105@arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Marc Zyngier Cc: "kvmarm@lists.cs.columbia.edu" List-Id: kvmarm@lists.cs.columbia.edu > On 24/02/15 14:36, Richard W.M. Jones wrote: > > I can probably bisect this given time, but I'm going to try putting > > some debug into the userspace process to find out which system call > > fails first. Perhaps not surprisingly, it's the init_module syscall which causes the failure, ie. this line of code: https://github.com/libguestfs/supermin/blob/master/src/init.c#L436 I've no idea why that code would call copy_to_user. It should be copying the other way ... It also fails on the first call to init_module, so the fact that it's loading crc32-arm64.ko may just be a coincidence. There are no other userspace processes running, but just to be sure that it's not some other process in the guest, I also added a sleep before the call to init_module, but same result as above. I also looked at the implementation of init_module in glibc, but AFAICT init_module is a straight syscall and glibc is not involved. I also looked to see if I was calling init_module correctly on aarch64 (in case it has a different # of arguments of something) but it's called in the same way in the libkmod code, so I think we're OK. Next up, I will have a go at bisecting the guest kernel. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/