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 00A3AC2D0E8 for ; Wed, 1 Apr 2020 00:35:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C8DCF20787 for ; Wed, 1 Apr 2020 00:35:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ek2hrAHc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731553AbgDAAfk (ORCPT ); Tue, 31 Mar 2020 20:35:40 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:56215 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729514AbgDAAfk (ORCPT ); Tue, 31 Mar 2020 20:35:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585701339; 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=nUYw2tAk2ElDzMusCcbVaLfYkke7kPKvnnUATst9aPY=; b=ek2hrAHcUHA0w0cTgSM7Dfn1kh+joOfUleB0FDjaUPtNyr6eRAzr+ME0v9D3k77SiWWpFx VcbdZwK/RaGVAzfNuWm5/mBi6GOnyAqxfmXcEfUiZuWFSE/5hi4Lo/6KmCuzFNBYxHzfVZ OD8uPYQNNVoajwlc3K5mgOMgcEg4dG4= 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-201-KPhDReGPMu24VIfo0neQTg-1; Tue, 31 Mar 2020 20:35:36 -0400 X-MC-Unique: KPhDReGPMu24VIfo0neQTg-1 Received: by mail-wr1-f70.google.com with SMTP id b2so13275946wrq.8 for ; Tue, 31 Mar 2020 17:35:35 -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=nUYw2tAk2ElDzMusCcbVaLfYkke7kPKvnnUATst9aPY=; b=mvh2HEeoKhLze2uP/sZ466Bik1vH72Xeo0nLz071A/pcD69g5df9RZHL0sRJis989N r/0Y+Q8HrcAonulRiTkZRVVvdOZkXVKwn1jdaAtWUuKaqNbzPJb+gzvnz6FOZzL/9em2 H+M7wxFSQDZAuPG4F8VtmAwLlWAhbv173/39W3uT8o86VfGAHnP53+gxerZSZW4Yhjik bgCnh5W4wHAzgJM/aL5zphc1+A1VZy+xXezecTJDw9GdUPIuXG3sTgXwTrJQgPg4kw3c 0XRazoXPhG9XLZIUzon38QjITCshnoWr5v12NAY22JU/0jhfIuZ40tAdiG7WYEUQga+o mrVw== X-Gm-Message-State: ANhLgQ3pTD3FH7Xtj5fkkQuty9RLCmLacZJcFRn8ZZI5STMfANv7J5Vx bBCdnBwxCvmXntcjmFgKavbnEO7tA0PJRZQWHiBUDvEnjFtbc4CoCF83qLaIJrwH6MSC6+cEchI 7QHyRjAneS/aX25pIgFf6zRcO X-Received: by 2002:a5d:6045:: with SMTP id j5mr22859745wrt.401.1585701335108; Tue, 31 Mar 2020 17:35:35 -0700 (PDT) X-Google-Smtp-Source: ADFU+vsu1SKpiUOGspGol9SelarOc4faOore5cmYKuXnJXLQ8H5FnAv74R3mri0v4DKf1Dgdrl2WkQ== X-Received: by 2002:a5d:6045:: with SMTP id j5mr22859728wrt.401.1585701334854; Tue, 31 Mar 2020 17:35:34 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:b55d:5ed2:8a41:41ea? ([2001:b07:6468:f312:b55d:5ed2:8a41:41ea]) by smtp.gmail.com with ESMTPSA id i21sm400563wmb.23.2020.03.31.17.35.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 31 Mar 2020 17:35:34 -0700 (PDT) Subject: Re: [PATCH v2 2/2] KVM: LAPIC: Don't need to clear IPI delivery status in x2apic mode To: Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel References: <1585700362-11892-1-git-send-email-wanpengli@tencent.com> <1585700362-11892-2-git-send-email-wanpengli@tencent.com> From: Paolo Bonzini Message-ID: <6de1a454-60fc-2bda-841d-f9ceb606d4c6@redhat.com> Date: Wed, 1 Apr 2020 02:35:33 +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: <1585700362-11892-2-git-send-email-wanpengli@tencent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/04/20 02:19, Wanpeng Li wrote: > - /* No delay here, so we always clear the pending bit */ > - val &= ~(1 << 12); > + /* Immediately clear Delivery Status in xAPIC mode */ > + if (!apic_x2apic_mode(apic)) > + val &= ~(1 << 12); This adds a conditional, and the old behavior was valid according to the SDM: "software should not assume the value returned by reading the ICR is the last written value". Paolo