Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933759AbcKXRMG (ORCPT ); Thu, 24 Nov 2016 12:12:06 -0500 Received: from mail-vk0-f45.google.com ([209.85.213.45]:36824 "EHLO mail-vk0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756694AbcKXRME (ORCPT ); Thu, 24 Nov 2016 12:12:04 -0500 MIME-Version: 1.0 From: Andy Lutomirski Date: Thu, 24 Nov 2016 09:11:41 -0800 Message-ID: Subject: FPU warning on x86_32 on Skylake To: Dave Hansen , Yu-cheng Yu Cc: X86 ML , Borislav Petkov , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1514 Lines: 34 I gett this when booting a 32-bit 4.9-rc6-ish on Skylake: [ 0.564506] ------------[ cut here ]------------ [ 0.564994] WARNING: CPU: 0 PID: 1 at ./arch/x86/include/asm/fpu/internal.h:368 fpu__restore+0x203/0x210 [ 0.565737] Modules linked in: [ 0.566040] CPU: 0 PID: 1 Comm: sh Not tainted 4.9.0-rc6+ #488 [ 0.566502] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-1.fc25 04/01/2014 [ 0.567174] c78a9e5c c135a6d0 00000000 c1ac4b4c c78a9e8c c10aeb42 c1ad53f0 00000000 [ 0.567896] 00000001 c1ac4b4c 00000170 c107e753 00000170 c78a06c0 00000000 c78a0700 [ 0.568583] c78a9ea0 c10aec05 00000009 00000000 00000000 c78a9eb8 c107e753 c78a0700 [ 0.569245] Call Trace: [ 0.569440] [] dump_stack+0x58/0x78 [ 0.569783] [] __warn+0xe2/0x100 [ 0.570109] [] ? fpu__restore+0x203/0x210 [ 0.570519] [] warn_slowpath_null+0x25/0x30 [ 0.570943] [] fpu__restore+0x203/0x210 [ 0.571312] [] __fpu__restore_sig+0x1fc/0x580 [ 0.571719] [] fpu__restore_sig+0x2a/0x50 [ 0.572103] [] restore_sigcontext.isra.10+0xbd/0xd0 [ 0.572546] [] sys_sigreturn+0x81/0x90 [ 0.572908] [] do_int80_syscall_32+0x57/0xc0 [ 0.573306] [] entry_INT80_32+0x2a/0x2a [ 0.573677] ---[ end trace 88038c46b2a9d23a ]--- Telling KVM to disable XSAVES makes the warning go away. I seem to be the only person testing 32-bit kernels on CPUs this new :-/ --Andy