[RH72 Spectre] ibpb_enabled = 1 leads to hard LOCKUP under x86_64 host machine

2018-01-20 Thread Hou Tao
Hi all, We are testing the patches for Spectre and Meltdown under OS derived from RH7.2, and hit by a hard LOCKUP panic under a x86_64 host environment. The hard LOCKUP can be reproduced, and it will gone if we disable ibpb by writing 0 to ibpb_enabled file, and it will appear again when we enabl

Re: [RH72 Spectre] ibpb_enabled = 1 leads to hard LOCKUP under x86_64 host machine

2018-01-20 Thread David Woodhouse
On Sat, 2018-01-20 at 17:00 +0800, Hou Tao wrote: > > So has anyone encountered a similar problem before, and any suggestions > and directions for the hard LOCKUP problems ? Arjan, what is the Intel recommendation here? smime.p7s Description: S/MIME cryptographic signature

RE: [RH72 Spectre] ibpb_enabled = 1 leads to hard LOCKUP under x86_64 host machine

2018-01-20 Thread Van De Ven, Arjan
: Hou Tao ; aarca...@redhat.com; linux- > ker...@vger.kernel.org; Van De Ven, Arjan > Cc: mi...@redhat.com; Thomas Gleixner ; > a...@linux.intel.com; dave.han...@linux.intel.com; pet...@infradead.org; > qiuxi...@huawei.com; wangkefeng.w...@huawei.com > Subject: Re: [RH72 Spectre] ibpb_

Re: [RH72 Spectre] ibpb_enabled = 1 leads to hard LOCKUP under x86_64 host machine

2018-01-20 Thread Andrea Arcangeli
Hello everyone, On Sat, Jan 20, 2018 at 01:56:08PM +, Van De Ven, Arjan wrote: > well first of all don't use IBRS, use retpoline This issue triggers in the IBPB code during user to user context switch and IBPB is still needed there no matter if kernel is using retpolines or if it uses kernel