From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EE110CA9EA0 for ; Tue, 22 Oct 2019 20:28:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8260214B2 for ; Tue, 22 Oct 2019 20:28:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388288AbfJVU2s (ORCPT ); Tue, 22 Oct 2019 16:28:48 -0400 Received: from mga09.intel.com ([134.134.136.24]:59402 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728832AbfJVU2s (ORCPT ); Tue, 22 Oct 2019 16:28:48 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Oct 2019 13:28:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,217,1569308400"; d="scan'208";a="203749927" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by FMSMGA003.fm.intel.com with ESMTP; 22 Oct 2019 13:28:47 -0700 Date: Tue, 22 Oct 2019 13:28:47 -0700 From: Sean Christopherson To: Derek Yerger Cc: Alex Williamson , kvm@vger.kernel.org, "Bonzini, Paolo" Subject: Re: PROBLEM: Regression of MMU causing guest VM application errors Message-ID: <20191022202847.GO2343@linux.intel.com> References: <1e525b08-6204-3238-5d56-513f82f1d7fb@djy.llc> <20191016112857.293a197d@x1.home> <20191016174943.GG5866@linux.intel.com> <53f506b3-e864-b3ca-f18f-f8e9a1612072@djy.llc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53f506b3-e864-b3ca-f18f-f8e9a1612072@djy.llc> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Oct 17, 2019 at 07:57:35PM -0400, Derek Yerger wrote: > On 10/16/19 1:49 PM, Sean Christopherson wrote: > >On Wed, Oct 16, 2019 at 11:28:57AM -0600, Alex Williamson wrote: > >>On Wed, 16 Oct 2019 00:49:51 -0400 > >>Derek Yerger wrote: > >> > >>>In at least Linux 5.2.7 via Fedora, up to 5.2.18, guest OS applications > >>>repeatedly crash with segfaults. The problem does not occur on 5.1.16. > >>> > >>>System is running Fedora 29 with kernel 5.2.18. Guest OS is Windows 10 with an > >>>AMD Radeon 540 GPU passthrough. When on 5.2.7 or 5.2.18, specific windows > >>>applications frequently and repeatedly crash, throwing exceptions in random > >>>libraries. Going back to 5.1.16, the issue does not occur. > >>> > >>>The host system is unaffected by the regression. > >>> > >>>Keywords: kvm mmu pci passthrough vfio vfio-pci amdgpu > >>> > >>>Possibly related: Unmerged [PATCH] KVM: x86/MMU: Zap all when removing memslot > >>>if VM has assigned device > >>That was never merged because it was superseded by: > >> > >>d012a06ab1d2 Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot" > >> > >>That revert also induced this commit: > >> > >>002c5f73c508 KVM: x86/mmu: Reintroduce fast invalidate/zap for flushing memslot > >> > >>Both of these were merged to stable, showing up in 5.2.11 and 5.2.16 > >>respectively, so seeing these sorts of issues might be considered a > >>known issue on 5.2.7, but not 5.2.18 afaik. Do you have a specific > >>test that reliably reproduces the issue? Thanks, > Test case 1: Kernel 5.2.18, PCI passthrough, Windows 10 guest, error condition. > Error 1: Application error in Firefox, restarting firefox and restoring tabs > reliably causes application crash with stack overflow error. > Error 2: Guest BSOD by the morning if left idle > Error 3: Guest BSOD within 1 minute of using SolidWorks CAD software > > Test case 2: Kernel 5.2.18, no PCI passthrough, same environment. Guest BSOD > encountered. > > Test case 3: Kernel 5.1.16, no PCI passthrough, same environment. Worked in > Solidworks for 10 minutes without BSOD. Opened firefox and restored tabs, no > crash. > > Test case 4: Kernel 5.1.16, with PCI passthrough, same environment. Worked > in Solidworks for a half hour. Opened firefox and restored tabs, no crash. > > Other factors: The guest does not change between tests. Same drivers, > software, etc. I have reliably switched between 5.2.x and 5.1.x multiple > times in the past month and repeatably see issues with 5.2.x. At this point > I'm unsure if it's PCI passthrough causing the problem. > > I know I should probably start from fresh host and guest, but time isn't > really permitting. > >Also, does the failure reproduce on on 5.2.1 - 5.2.6? The memslot debacle > >exists on all flavors of 5.2.x, if the errors showed up in 5.2.7 then they > >are being caused by something else. > After experiencing the issue in absence of PCI passthrough, I believe the > problem is unrelated to the memslot debacle. Heh, should've checked from the get go... It's definitely not the memslot issue, because the memslot bug is in 5.1.16 as well. :-) > I'm stuck on 5.1.x for now, maybe I'll give up and get a dedicated windows > machine /s What hardware are you running on? I was thinking this was AMD specific, but then realized you said "AMD Radeon 540 GPU" and not "AMD CPU".