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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 84E9BC43381 for ; Mon, 1 Apr 2019 10:41:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5B3D720883 for ; Mon, 1 Apr 2019 10:41:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727005AbfDAKl4 (ORCPT ); Mon, 1 Apr 2019 06:41:56 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:35181 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726192AbfDAKlz (ORCPT ); Mon, 1 Apr 2019 06:41:55 -0400 Received: by mail-wm1-f67.google.com with SMTP id y197so10783121wmd.0 for ; Mon, 01 Apr 2019 03:41:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version:content-transfer-encoding; bh=CIkPZ4hE+jyUzNonViu5/h2dRfSbj83iTiTZgWvTnBA=; b=kr36ozrnDzffmocpii+eG2SQo1YvL8m/jLALZSFxPx88JKlrZqvxq9YCWfRDcr6sib JWcY+GY6D/VptqBWnrkkmWT+8l4cfZPkigVha3VwvHcCKAzosEtHSMU5l7yQA3xuxcmf juqTtWfxJHsnPeyEv0q/9Kvulv1t+wQUvEPzdtFN6p22/odMb0dCSqv/YQpt9L0kz4aI 160I1E0qrE2FTBF98UWAi1ToL7vG7sL6yoi6E0ndQQnX3eTDzSwXPsrwsTlBiMGdKzWi zmYTLs4uit1VFndm7SWYZjSQNO65wgmli+VJHZAc9Y8fQKlXEaZ/DdZWGyBbPsGqv3Go CYGA== X-Gm-Message-State: APjAAAXsl0t2HoqY9P4cEFAbKwRiUFYtv3jf9KWHcIYjyW8VDP+Zc0Tn ax0fVb9yjQT4BxmPJlqXgz+uuXFUXZE= X-Google-Smtp-Source: APXvYqyqpAbd3xpQVRe9HrP/otEoQg1vkR4RMyqY0RKUmUutDNa6+cunCCHTEnjtqAUQyUuxrnJFUQ== X-Received: by 2002:a7b:c743:: with SMTP id w3mr12372088wmk.75.1554115313595; Mon, 01 Apr 2019 03:41:53 -0700 (PDT) Received: from vitty.brq.redhat.com (nat-pool-brq-t.redhat.com. [213.175.37.10]) by smtp.gmail.com with ESMTPSA id q17sm8137644wrw.70.2019.04.01.03.41.52 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 01 Apr 2019 03:41:52 -0700 (PDT) From: Vitaly Kuznetsov To: Liran Alon Cc: Paolo Bonzini , kvm@vger.kernel.org, Radim =?utf-8?B?S3LEjW3DocWZ?= , Sean Christopherson , linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] KVM: x86: vmx: throttle immediate exit through preemtion timer to assist buggy guests In-Reply-To: References: <20190328203110.20655-1-vkuznets@redhat.com> <87d0m93frp.fsf@vitty.brq.redhat.com> <89d4189b-de6a-7634-de8b-29a044a86e12@redhat.com> <63F1B6AE-F7A0-40D9-9582-558723800682@oracle.com> <32296de3-8ce0-c20a-5948-a7eef267a328@redhat.com> <87v9zy15mc.fsf@vitty.brq.redhat.com> Date: Mon, 01 Apr 2019 12:41:51 +0200 Message-ID: <87lg0u0zyo.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Liran Alon writes: > So to sum-up: This matches what I mentioned in my previous emails right? > That vector 96 is not related, and the only issue here is that level-triggered interrupt handler for vector 80 is doing EOI before lowering the irq-line. > Which cause vector 80 to be injected in infinite loop. > And this is not even related to being a nested virtualization > workload. It’s just an issue in Hyper-V (L1) interrupt handler for > vector 80. Yes, it may be related to how communications between Hyper-V and Windows partition are organized but it's a pure speculation. > > Therefore the only action-items are: > 1) Microsoft to fix Hyper-V vector 80 interrupt handler to lower irq-line before EOI. > 2) Patch QEMU IOAPIC implementation to have a mechanism similar to KVM to delay injection of level-triggered interrupt > in case we are injecting the same interrupt for X times in a row. I'm intended to do 2) and we already let MS know there's an issue. Thanks for your help with the investigation guys! -- Vitaly