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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C8836C433ED for ; Thu, 22 Apr 2021 07:19:01 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 46B1060200 for ; Thu, 22 Apr 2021 07:19:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46B1060200 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bugs.launchpad.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:56430 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lZTc4-0003Wr-7c for qemu-devel@archiver.kernel.org; Thu, 22 Apr 2021 03:19:00 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56094) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lZTZJ-0007qQ-Np for qemu-devel@nongnu.org; Thu, 22 Apr 2021 03:16:10 -0400 Received: from indium.canonical.com ([91.189.90.7]:36212) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lZTZD-0003gm-Ru for qemu-devel@nongnu.org; Thu, 22 Apr 2021 03:16:09 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.86_2 #2 (Debian)) id 1lZTZ9-0004Jz-CT for ; Thu, 22 Apr 2021 07:15:59 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 5D9092E8167 for ; Thu, 22 Apr 2021 07:15:59 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 22 Apr 2021 07:09:19 -0000 From: Thomas Huth <1837851@bugs.launchpad.net> To: qemu-devel@nongnu.org X-Launchpad-Notification-Type: bug X-Launchpad-Bug: product=qemu; status=Incomplete; importance=Undecided; assignee=None; X-Launchpad-Bug-Tags: kvm qemu-kvm x86 X-Launchpad-Bug-Information-Type: Public X-Launchpad-Bug-Private: no X-Launchpad-Bug-Security-Vulnerability: no X-Launchpad-Bug-Commenters: stefan-proxmox th-huth X-Launchpad-Bug-Reporter: Stefan (stefan-proxmox) X-Launchpad-Bug-Modifier: Thomas Huth (th-huth) References: <156404155054.10633.9207967667458929652.malonedeb@wampee.canonical.com> Message-Id: <161907535935.490.12728673692587499742.malone@soybean.canonical.com> Subject: [Bug 1837851] Re: hv-tlbflush malfunctions on Intel host CPUs with neither EPT nor VPID (qemu-kvm) X-Launchpad-Message-Rationale: Subscriber (QEMU) @qemu-devel-ml X-Launchpad-Message-For: qemu-devel-ml Precedence: bulk X-Generated-By: Launchpad (canonical.com); Revision="1552fceb1603b3da6cfa437575d9c9fc4b2e683a"; Instance="production" X-Launchpad-Hash: a0883d7d17bca847142aa6581499f1d8b287b8de Received-SPF: none client-ip=91.189.90.7; envelope-from=bounces@canonical.com; helo=indium.canonical.com X-Spam_score_int: -65 X-Spam_score: -6.6 X-Spam_bar: ------ X-Spam_report: (-6.6 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Bug 1837851 <1837851@bugs.launchpad.net> Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The QEMU project is currently considering to move its bug tracking to another system. For this we need to know which bugs are still valid and which could be closed already. Thus we are setting older bugs to "Incomplete" now. If you still think this bug report here is valid, then please switch the state back to "New" within the next 60 days, otherwise this report will be marked as "Expired". Or please mark it as "Fix Released" if the problem has been solved with a newer version of QEMU already. Thank you and sorry for the inconvenience. ** Changed in: qemu Status: New =3D> Incomplete -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1837851 Title: hv-tlbflush malfunctions on Intel host CPUs with neither EPT nor VPID (qemu-kvm) Status in QEMU: Incomplete Bug description: Enabling hv-tlbflush on older hosts using Intel CPUs supporting VT-x but neither EPT nor VPID will lead to bluescreens on the guest. It seems KVM only checks if EPT is available, and if it isn't it forcibly uses VPID. If that's *also* not available, it defaults to basically a no-op hypercall, though windows is expecting the TLB to be flushed. hv-tlbflush is pretty useless on machines not supporting these extensions anyway (only reasonably fix I can see would be to flush the *entire* TLB on tlbflush hypercall in KVM (i.e. a kernel fix), but that would remove any performance benefits), so I would suggest some kind of preliminary check and warning/error if hv-tlbflush is specified on such a host. All CPUs mentioned in this thread[0] are confirmed to be affected by the bug, and I have successfully reproduced it on an Intel Core2Duo E8500. [0] https://forum.proxmox.com/threads/windows-guest-bluescreen-with- proxmox-6.56053/ To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1837851/+subscriptions