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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_IN_DEF_DKIM_WL 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 804B0ECDE32 for ; Wed, 17 Oct 2018 17:08:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 47B1E21476 for ; Wed, 17 Oct 2018 17:08:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="iY5Szprq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 47B1E21476 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727837AbeJRBFa (ORCPT ); Wed, 17 Oct 2018 21:05:30 -0400 Received: from mail-ot1-f65.google.com ([209.85.210.65]:33708 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727332AbeJRBF3 (ORCPT ); Wed, 17 Oct 2018 21:05:29 -0400 Received: by mail-ot1-f65.google.com with SMTP id q50so26970448otd.0 for ; Wed, 17 Oct 2018 10:08:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=Y/xr2rqqnO4M3YntWem4HxiuPTbdciA7bGfMU/F7Dy4=; b=iY5Szprq2KvTmBERmlxfHZWQJ5/PM3zXEiNBifrBR4KJo52vkULdEFO+wIk/SlIbFQ FScSN6brL46IIFp1DMMmvnN2vC0Ne+i+bPy8JUR6uaPfyHgMAOsPnxtm5pob/mhit8YH Sdfb8INU+FnpQ8DBFYq1ccSSvtMzYWkWVoT3n7tR6bx+VOdR5DsQbXMq+IW0qCvkhPHK CE5EWTuIn6kSlDrNayzhOggSwUez55UuH7CxCDxs1JorzetFuhGpVn54s3DV3FJwLKF4 +Tx7lYuWMoD0MX3B6QfGc7UbkZmMO9ysOcfcA36C9vbdzPPFDT6PSr0ZTyMQd9sDA4LE WPRQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=Y/xr2rqqnO4M3YntWem4HxiuPTbdciA7bGfMU/F7Dy4=; b=Bn4i/trlkSR0QUirgypSye4gP7+W3yJDFuAmlDgv+4XXDxqQ0TuxZNKej+P9ACmCo1 uVWeOmsZ0xuBu03SE1pE5zhbgcpD5vIj4Gs72ft1ByNYRvkBuck1B0NeiiOXFCED2uZ+ UqnFANRW5asEPDg9l90wuIwp9MUvlnbxL8vxGelCJ1Hsc6jfqb55f1qcyDcjRoADXeWV hg6t1Is6+lLa5EAi+3c7CgsslKc2EzFJ34cusIQQ1ByZ6UGnpMsP1Kxb5LWbfpym3XBu b4RyGO5+2oXYGKnugaOAGiHiTgWjV9WHLaz4nmKxbAdjHg3cQGHjv/DDES6I7w35mjAX 8XEA== X-Gm-Message-State: ABuFfohXJeg0D3iiGmdlMeZ193kKKCG6Uo55UT+eeMDsDUPmGBvRIkTH jPTsc38jSuixthWIC72JfCK8b9srfDSfPw7BNqckig== X-Google-Smtp-Source: ACcGV60jw5aNarwg6KdKhs+bn5yJOFj2QMIJ1MuUh77YqPhy8pbngXgPwvb8X5E2qM5r7gx/rUXy88z0g4XBgAZDC4M= X-Received: by 2002:a9d:4d0c:: with SMTP id n12mr17909059otf.90.1539796131829; Wed, 17 Oct 2018 10:08:51 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:ac9:2aca:0:0:0:0:0 with HTTP; Wed, 17 Oct 2018 10:08:51 -0700 (PDT) In-Reply-To: <0ff3acb0-1d20-cbb0-5f40-887d9db93d9e@redhat.com> References: <20181016165011.6607-1-vkuznets@redhat.com> <20181016165011.6607-7-vkuznets@redhat.com> <2064be05-4286-e3d5-cd22-13fd957b7003@redhat.com> <8736t4sk8w.fsf@vitty.brq.redhat.com> <0ff3acb0-1d20-cbb0-5f40-887d9db93d9e@redhat.com> From: Jim Mattson Date: Wed, 17 Oct 2018 10:08:51 -0700 Message-ID: Subject: Re: [PATCH v6 06/13] KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case To: Paolo Bonzini Cc: Vitaly Kuznetsov , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Roman Kagan , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , "Michael Kelley (EOSG)" , LKML , Liran Alon , kvm list Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I believe that ESXi reads GUEST_CS_AR_BYTES on every VM-exit to determine code size. On Wed, Oct 17, 2018 at 10:02 AM, Paolo Bonzini wrote: > On 17/10/2018 16:47, Vitaly Kuznetsov wrote: >>>> + if (!hv_evmcs || !(hv_evmcs->hv_clean_fields & >>>> + HV_VMX_ENLIGHTENED_CLEAN_FIELD_GUEST_GRP2)) { >>>> + vmcs_write16(GUEST_CS_SELECTOR, vmcs12->guest_cs_selector); >>>> + vmcs_write32(GUEST_CS_LIMIT, vmcs12->guest_cs_limit); >>>> + vmcs_write32(GUEST_CS_AR_BYTES, vmcs12->guest_cs_ar_bytes); >>>> + vmcs_writel(GUEST_ES_BASE, vmcs12->guest_es_base); >>>> + vmcs_writel(GUEST_CS_BASE, vmcs12->guest_cs_base); >>>> + } >>> For what it's worth, I suspect that these can be moved to >>> prepare_vmcs02_full. The initial implementation of shadow VMCS did not >>> expose "unrestricted guest" to the L1 hypervisor, and emulation does a >>> lot of accesses to CS (of course). Not sure how ES base ended up in >>> there and not DS base, though... >> I tried unshadowing all these fields and at least Hyper-V on KVM >> (without using eVMCS of course) experiences a 1200-1300 cpu cycles >> regression during tight cpuid loop test. I checked and this happens >> because it likes vmreading GUEST_CS_AR_BYTES a lot. > > Go figure. :) Liran, do you happen to know if ESX does something > similar with CS descriptor cache fields? > > Paolo