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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 3C9A2C2BB1D for ; Tue, 7 Apr 2020 22:07:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17F5220747 for ; Tue, 7 Apr 2020 22:07:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="i5x7nUVc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726438AbgDGWH3 (ORCPT ); Tue, 7 Apr 2020 18:07:29 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:43154 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726393AbgDGWH2 (ORCPT ); Tue, 7 Apr 2020 18:07:28 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586297247; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sBcX0MuRfqdKJ/UDy2UrC0OesweN1b1Dk27ZzjJGB5Y=; b=i5x7nUVcUE15gTgNu7HGfc186JHjuWRAMJBdPdt5y02HgtTqwUGTpVHqv00xyDTxa6E/0E iNPOnA4NptlPF8XrJERZxclW5ZM2cGerwWXUgmVz06kzm/YDAHNuZU73HUapJ+QEDalllV vgo0BjAT6bdamXo4T/CXdd4Vb5p2G0k= Received: from mail-wr1-f70.google.com (mail-wr1-f70.google.com [209.85.221.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-432-F_qMV2c6MYOrhNFNYagm8Q-1; Tue, 07 Apr 2020 18:07:26 -0400 X-MC-Unique: F_qMV2c6MYOrhNFNYagm8Q-1 Received: by mail-wr1-f70.google.com with SMTP id j12so2896613wrr.18 for ; Tue, 07 Apr 2020 15:07:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=sBcX0MuRfqdKJ/UDy2UrC0OesweN1b1Dk27ZzjJGB5Y=; b=CmvBIftVHnQNqxjZSExVsZkRnZU0PfOs3D/ry+2a+kzS6SwcpmwNP2WGYN5hIr6D5M x4Dv1i9OZ4aPeDHLs+JfTzYsXlW4NpQgRaxYY2IuDNu3YA6aFm16z7vC98bDItrOpbK2 F0sqs+Lyi1QDuplvsJzl8h2L5VJT2+/vHkwFJPS1V1HC9FC/rsLFET3UI+mIRNQZjYC1 8a6dcFG9IpZiYJU7qpjy5/xHVKITNppl8w0YN0f2Sq11uFI4q9rGVbMRQmelWm6uYif6 n5kufWuyZzUd5shYEuSFH/E6vhPgpkFT8CdPLo2/7w9BMAqWr6snZ1zK30OVuQIkTDXp axUA== X-Gm-Message-State: AGi0PuahkK70viI7GMUFkwxFTSxhEGTIlK2EfLgdDjMIkolgKCILZq1O kIsSw85SWrhEl0BlozJyBanp27ead2qSaKOATzRzYWhtZFWTpD3eBv5kdfR8etlcPfxihMhQVzr +WlbSo5rxzi5c X-Received: by 2002:adf:b64f:: with SMTP id i15mr5190283wre.351.1586297244868; Tue, 07 Apr 2020 15:07:24 -0700 (PDT) X-Google-Smtp-Source: APiQypLm4s/z1WuBmAjFihAoIU+l3M3dmlXE9c2JCfBcrBn/lXHVlRvx1DDkIp0weC8LKHXvuX6Bwg== X-Received: by 2002:adf:b64f:: with SMTP id i15mr5190263wre.351.1586297244650; Tue, 07 Apr 2020 15:07:24 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:bd61:914:5c2f:2580? ([2001:b07:6468:f312:bd61:914:5c2f:2580]) by smtp.gmail.com with ESMTPSA id w66sm3973000wma.38.2020.04.07.15.07.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 07 Apr 2020 15:07:24 -0700 (PDT) Subject: Re: [PATCH v2] x86/kvm: Disable KVM_ASYNC_PF_SEND_ALWAYS To: Andy Lutomirski , Thomas Gleixner Cc: Vivek Goyal , Peter Zijlstra , Andy Lutomirski , LKML , X86 ML , kvm list , stable References: <87eeszjbe6.fsf@nanos.tec.linutronix.de> From: Paolo Bonzini Message-ID: <2776fced-54c2-40eb-7921-1c68236c7f70@redhat.com> Date: Wed, 8 Apr 2020 00:07:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 07/04/20 23:41, Andy Lutomirski wrote: > 2. Access to bad memory results in #MC. Sure, #MC is a turd, but > it’s an *architectural* turd. By all means, have a nice simple PV > mechanism to tell the #MC code exactly what went wrong, but keep the > overall flow the same as in the native case. > > I think I like #2 much better. It has another nice effect: a good > implementation will serve as a way to exercise the #MC code without > needing to muck with EINJ or with whatever magic Tony uses. The > average kernel developer does not have access to a box with testable > memory failure reporting. I prefer #VE, but I can see how #MC has some appeal. However, #VE has a mechanism to avoid reentrancy, unlike #MC. How would that be better than the current mess with an NMI happening in the first few instructions of the #PF handler? Paolo