From: "Herongguang (Stephen)" Subject: Re: [Qemu-devel] kvm bug in __rmap_clear_dirty during live migration Date: Fri, 24 Feb 2017 17:35:17 +0800 Message-ID: <58AFFE55.20306@huawei.com> References: <589C7E96.9060905@huawei.com> <589D83CE.1090803@huawei.com> <589DDC05.9010807@windriver.com> <58AA51D6.6020508@huawei.com> <1487565495.3740.27.camel@intel.com> <58AD0094.90304@windriver.com> <4dd92012-626a-2d80-9adb-0be398f73eb1@redhat.com> <58AD92AE.6040502@windriver.com> <6c5567f4-192d-aefd-90e4-89f53479c24e@redhat.com> <58AF9921.6060201@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Cc: Paolo Bonzini , Chris Friesen , "Han, Huaitong" , "hangaohuai@huawei.com" , , "kvm@vger.kernel.org" , "fangying1@huawei.com" , "xudong.hao@linux.intel.com" , "qemu-devel@nongnu.org" , "wangxinxin.wang@huawei.com" , "kai.huang@linux.intel.com" , "rkrcmar@redhat.com" , "guangrong.xiao@linux.intel.com" , To: Return-path: Received: from szxga03-in.huawei.com ([45.249.212.189]:2957 "EHLO dggrg03-dlp.huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750964AbdBXJgA (ORCPT ); Fri, 24 Feb 2017 04:36:00 -0500 In-Reply-To: <58AF9921.6060201@huawei.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2017/2/24 10:23, Herongguang (Stephen) wrote: > > > On 2017/2/22 22:43, Paolo Bonzini wrote: >> >> >> On 22/02/2017 14:31, Chris Friesen wrote: >>>>> >>>> >>>> Can you reproduce it with kernel 4.8+? I'm suspecting commmit >>>> 4e59516a12a6 ("kvm: vmx: ensure VMCS is current while enabling PML", >>>> 2016-07-14) to be the fix. >>> >>> I can't easily try with a newer kernel, the software package we're using >>> has kernel patches that would have to be ported. >>> >>> I'm at a conference, don't really have time to set up a pair of test >>> machines from scratch with a custom kernel. >> >> Hopefully Gaohuai and Rongguang can help with this too. >> >> Paolo >> >> . >> > Yes, we are looking into and testing this. > > I think this can result in any memory corruption, if VM1 writes its > PML buffer into VM2’s VMCS (since sched_in/sched_out notifier of VM1 > is not registered yet), then VM1 is destroyed (hence its PML buffer > is freed back to kernel), after that, VM2 starts migration, so CPU > logs VM2’s dirty GFNS into a freed memory, results in any memory corruption. > > As its severity, this commit (http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4e59516a12a6ef6dcb660cb3a3f70c64bd60cfec) > is eligible to back port to kernel stable. Hi, Greg, can you cherry pick commit 4e59516a12a6ef6dcb660cb3a3f70c64bd60cfec to 4.4-y?