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=unavailable 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 41AFCC10F12 for ; Mon, 15 Apr 2019 12:27:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 184152077C for ; Mon, 15 Apr 2019 12:27:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727339AbfDOM1j (ORCPT ); Mon, 15 Apr 2019 08:27:39 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:55540 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727243AbfDOM1j (ORCPT ); Mon, 15 Apr 2019 08:27:39 -0400 Received: by mail-wm1-f67.google.com with SMTP id o25so20398900wmf.5 for ; Mon, 15 Apr 2019 05:27:38 -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; bh=NFkaEcrMcC+TkQE3T7eDIT8t/gt8OW6BPDneAKgJs0E=; b=CXr5mhULlcPn6g9N9uljdMfF5wF0Q027EcyF47Zet5GxSdlSF1zilXEjLFB0L6BffI uoGr2ESQaOEn4SU7jMvGh1xfaRg9XdWS568lhDxi6Hpe7xyL+r524nnAMcQf2/jlUPsy n2EE/+rO7lY00HFnqNH0/EPEuYaJPz/wIz1PPwOBl6fjcP4oXUD529H5BxWif6KRnj9f m3MJPs6kq9SLtUL1anVwHCwxkUw4toOl1SAtsy+qHBB61ahui2G/ZyUzyQymgCR8kqaX wX6AO/vasqg0tEV5WWiGOXOvveL15krLk/QRb7l1SXfIXnShVWI8R2evaZMHibtQhK6Z /fEw== X-Gm-Message-State: APjAAAWX19JoyDtbHfctgdCiNH/Q1e0VMGtsSixrxBt463LugR+kDC/b u8oKh3q1bYirP+kMH/eK0LWHYexO4Io= X-Google-Smtp-Source: APXvYqy10B54Sg22aN8scwrJY70VAnPjGpILUNo7T8gOq70S1eMMaCDd8f8pJBO2stBk04EayG0PsQ== X-Received: by 2002:a7b:c086:: with SMTP id r6mr22390739wmh.123.1555331257642; Mon, 15 Apr 2019 05:27:37 -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 o1sm19020108wmh.47.2019.04.15.05.27.36 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 15 Apr 2019 05:27:36 -0700 (PDT) From: Vitaly Kuznetsov To: Long Li , Simon Xiao Cc: x86@kernel.org, linux-kernel@vger.kernel.org, "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Sasha Levin , "Michael Kelley \(EOSG\)" , linux-hyperv@vger.kernel.org Subject: Re: [PATCH] x86/hyper-v: implement EOI assist In-Reply-To: <20190403170309.4107-1-vkuznets@redhat.com> References: <20190403170309.4107-1-vkuznets@redhat.com> Date: Mon, 15 Apr 2019 14:27:36 +0200 Message-ID: <87v9zfh2rr.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-hyperv-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org Vitaly Kuznetsov writes: > Hyper-V TLFS suggests an optimization to avoid imminent VMExit on EOI: > "The OS performs an EOI by atomically writing zero to the EOI Assist field > of the virtual VP assist page and checking whether the "No EOI required" > field was previously zero. If it was, the OS must write to the > HV_X64_APIC_EOI MSR thereby triggering an intercept into the hypervisor." > > Implement the optimization in Linux. > Simon, Long, did you get a chance to run some tests with this? -- Vitaly