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=-12.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,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 4CD66C63777 for ; Mon, 30 Nov 2020 15:35:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E41562076E for ; Mon, 30 Nov 2020 15:35:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="VDg7bIf8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727513AbgK3PfB (ORCPT ); Mon, 30 Nov 2020 10:35:01 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:48697 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726928AbgK3PfA (ORCPT ); Mon, 30 Nov 2020 10:35:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606750414; 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=FQatalQEFsFszop7DIO2Ob5g7uuYov1pLoszVHjjbgk=; b=VDg7bIf8OZcLREUqCjj/cQyThH7bXhgILWBWYLszqdncDUsRyfazqWdVj2/zn2UqjNYsFH SqzzJKlK/NWLCD4Rt2B3lHPN8iKCdRNm0pSDRTfTqe4G9jBryJs2r7XgfMCSaajkuewrka fFjcPZKgc/yPVVI9Xz3/xXt7U4e+faQ= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-415-5J4J05ODOcqkm__noHraNA-1; Mon, 30 Nov 2020 10:33:30 -0500 X-MC-Unique: 5J4J05ODOcqkm__noHraNA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 85D097FE41; Mon, 30 Nov 2020 15:33:26 +0000 (UTC) Received: from starship (unknown [10.35.206.90]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4989C5C233; Mon, 30 Nov 2020 15:33:16 +0000 (UTC) Message-ID: <989974f32eab61187557239172c603857d4bd837.camel@redhat.com> Subject: Re: [PATCH 2/2] KVM: x86: introduce KVM_X86_QUIRK_TSC_HOST_ACCESS From: Maxim Levitsky To: Paolo Bonzini , kvm@vger.kernel.org Cc: Oliver Upton , Ingo Molnar , Sean Christopherson , Thomas Gleixner , open list , Marcelo Tosatti , Jonathan Corbet , Wanpeng Li , Borislav Petkov , Jim Mattson , "H. Peter Anvin" , "open list:DOCUMENTATION" , Joerg Roedel , "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , Vitaly Kuznetsov Date: Mon, 30 Nov 2020 17:33:15 +0200 In-Reply-To: <5e77e912-893b-0c8f-a9a6-b43eaee24ed3@redhat.com> References: <20201130133559.233242-1-mlevitsk@redhat.com> <20201130133559.233242-3-mlevitsk@redhat.com> <638a2919cf7c11c55108776beecafdd8e2da2995.camel@redhat.com> <5e77e912-893b-0c8f-a9a6-b43eaee24ed3@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.3 (3.36.3-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2020-11-30 at 15:15 +0100, Paolo Bonzini wrote: > On 30/11/20 15:11, Maxim Levitsky wrote: > > On Mon, 2020-11-30 at 14:54 +0100, Paolo Bonzini wrote: > > > On 30/11/20 14:35, Maxim Levitsky wrote: > > > > This quirk reflects the fact that we currently treat MSR_IA32_TSC > > > > and MSR_TSC_ADJUST access by the host (e.g qemu) in a way that is different > > > > compared to an access from the guest. > > > > > > > > For host's MSR_IA32_TSC read we currently always return L1 TSC value, and for > > > > host's write we do the tsc synchronization. > > > > > > > > For host's MSR_TSC_ADJUST write, we don't make the tsc 'jump' as we should > > > > for this msr. > > > > > > > > When the hypervisor uses the new TSC GET/SET state ioctls, all of this is no > > > > longer needed, thus leave this enabled only with a quirk > > > > which the hypervisor can disable. > > > > > > > > Suggested-by: Paolo Bonzini > > > > Signed-off-by: Maxim Levitsky > > > > > > This needs to be covered by a variant of the existing selftests testcase > > > (running the same guest code, but different host code of course). > > Do you think that the test should go to the kernel's kvm unit tests, > > or to kvm-unit-tests project? > > The latter already has x86_64/tsc_msrs_test.c (which I created in > preparation for this exact change :)). I'll prepare a test then for it! Best regards, Maxim Levitsky > > Paolo >