From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52152) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c4OCA-00066u-HH for qemu-devel@nongnu.org; Wed, 09 Nov 2016 03:25:23 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c4OC6-0004do-Ig for qemu-devel@nongnu.org; Wed, 09 Nov 2016 03:25:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57682) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c4OC6-0004dQ-BO for qemu-devel@nongnu.org; Wed, 09 Nov 2016 03:25:18 -0500 Date: Wed, 9 Nov 2016 16:25:10 +0800 From: Dave Young Message-ID: <20161109082510.GA6197@dhcp-128-65.nay.redhat.com> References: <20161109030146.GA3802@dhcp-128-65.nay.redhat.com> <20161109031729.GA3675@dhcp-128-65.nay.redhat.com> <962ee966-641a-2f74-3e26-7c7967fa8f7e@cn.fujitsu.com> <20161109050248.GA4431@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] virsh dump (qemu guest memory dump?): KASLR enabled linux guest support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wen Congyang Cc: anderson@redhat.com, lersek@redhat.com, qemu-devel@nongnu.org, bhe@redhat.com On 11/09/16 at 03:42pm, Wen Congyang wrote: > On 11/09/2016 01:02 PM, Dave Young wrote: > > On 11/09/16 at 11:58am, Wen Congyang wrote: > >> On 11/09/2016 11:17 AM, Dave Young wrote: > >>> Drop qiaonuohan, seems the mail address is wrong.. > >>> > >>> On 11/09/16 at 11:01am, Dave Young wrote: > >>>> Hi, > >>>> > >>>> Latest linux kernel enabled kaslr to randomiz phys/virt memory > >>>> addresses, we had some effort to support kexec/kdump so that crash > >>>> utility can still works in case crashed kernel has kaslr enabled. > >>>> > >>>> But according to Dave Anderson virsh dump does not work, quoted messages > >>>> from Dave below: > >>>> > >>>> """ > >>>> with virsh dump, there's no way of even knowing that KASLR > >>>> has randomized the kernel __START_KERNEL_map region, because there is no > >>>> virtual address information -- e.g., like "SYMBOL(_stext)" in the kdump > >>>> vmcoreinfo data to compare against the vmlinux file symbol value. > >>>> Unless virsh dump can export some basic virtual memory data, which > >>>> they say it can't, I don't see how KASLR can ever be supported. > >>>> """ > >>>> > >>>> I assume virsh dump is using qemu guest memory dump facility so it > >>>> should be first addressed in qemu. Thus post this query to qemu devel > >>>> list. If this is not correct please let me know. > >> > >> IIRC, 'virsh dump --memory-only' uses dump-guest-memory, and 'virsh dump' > >> uses migration to dump. > > > > Do they need different fixes? Dave, I guess you mean --memory-only, but > > could you clarify and confirm it? > > > >> > >> I think I should study kaslr first... > > > > Thanks for taking care of it. > > Can you give me the patch for kexec/kdump. I want to know what I need to do > for dump-guest-memory. AFAIK, there are below patches for kexec/kdump userspace: kexec-tools, git commit: commit 9f62cbddddfc93d78d9aafbddf3e1208cb242f7b Author: Thomas Garnier Date: Tue Sep 13 15:10:05 2016 +0800 kexec/arch/i386: Add support for KASLR memory randomization Originally Baoquan He posted below patches to export vmcoreinfo for some kernel fields: http://lists.infradead.org/pipermail/kexec/2016-September/017191.html But later it was dropped, we finally do it in userspace with several makedumpfile patches: http://lists.infradead.org/pipermail/kexec/2016-October/017540.html http://lists.infradead.org/pipermail/kexec/2016-October/017539.html http://lists.infradead.org/pipermail/kexec/2016-October/017541.html For virsh dumped vmcore it should manage to export some infomation so that crash utility can use. I would leave Dave to provide more information what he needs because the goal is userspace utility like crash can correctly analysis the vmcore. > > Thanks > Wen Congyang > > > > >> > >> Thanks > >> Wen Congyang > >> > >>>> > >>>> Could you qemu dump people make it work? Or we can not support virt dump > >>>> as long as KASLR being enabled. Latest Fedora kernel has enabled it in x86_64. > >>>> > >>>> Thanks > >>>> Dave > >>> > >>> > >>> > >> > >> > >> > > > > > > . > > > > >