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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6E97CC3F2D1 for ; Sat, 7 Mar 2020 20:09:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 43A512073C for ; Sat, 7 Mar 2020 20:09:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726330AbgCGUJC (ORCPT ); Sat, 7 Mar 2020 15:09:02 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:55853 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726109AbgCGUJB (ORCPT ); Sat, 7 Mar 2020 15:09:01 -0500 Received: from p5de0bf0b.dip0.t-ipconnect.de ([93.224.191.11] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jAfkn-0007yO-4D; Sat, 07 Mar 2020 21:08:57 +0100 Received: by nanos.tec.linutronix.de (Postfix, from userid 1000) id 7B520104088; Sat, 7 Mar 2020 21:08:56 +0100 (CET) From: Thomas Gleixner To: Andy Lutomirski Cc: Andy Lutomirski , LKML , X86 ML , Paolo Bonzini , KVM , "Paul E. McKenney" Subject: Re: [patch 2/2] x86/kvm: Sanitize kvm_async_pf_task_wait() In-Reply-To: References: <20200306234204.847674001@linutronix.de> <20200307000259.448059232@linutronix.de> <87r1y4a3gw.fsf@nanos.tec.linutronix.de> <87d09o9n7y.fsf@nanos.tec.linutronix.de> Date: Sat, 07 Mar 2020 21:08:56 +0100 Message-ID: <8736ak9bc7.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andy Lutomirski writes: > On Sat, Mar 7, 2020 at 7:52 AM Thomas Gleixner wrote: >> WHAT? That's fundamentally broken. Can you point me to the code in >> question? > > I think Paolo said so in a different thread, but I can't Let me see if > I can find it: > > kvm_pv_enable_async_pf() > kvm_clear_async_pf_completion_queue() > > but that doesn't actually seem to send #PF. So maybe I'm wrong. > > I will admit that, even after reading the host code a few times, I'm > also not convinced that wakeups don't get swallowed on occasion if > they would have been delivered at times when it's illegal. I gave up trying to decode it. I wait for the kvm wizards to answer all our nasty questions :) Thanks, tglx