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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2371CC4332F for ; Thu, 13 Oct 2022 09:16:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229769AbiJMJQf (ORCPT ); Thu, 13 Oct 2022 05:16:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53838 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229659AbiJMJQb (ORCPT ); Thu, 13 Oct 2022 05:16:31 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2AFA920BDB for ; Thu, 13 Oct 2022 02:16:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1665652586; 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: in-reply-to:in-reply-to:references:references; bh=c1PougXwFNeOBx9Qjbr5s56x+6pgJ2sjuaM5Urh09Fk=; b=hi7Sxs3NUN5tw74/8sYvvgVIUK8SB5X2/LwQmwLLi28U1NhOwQUi8ykWVXfSUFBrXEJ/l8 xpxmpjd81gFK/6a/KiWWrDNc2mYmjUssfVDk3Lcclll7R6olcLfPAofB6bNHhb/ThLJOyS LleJ1zdyp3vTSwPWCjpFeNXr+s6JT08= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-490-pkM7bIR4P-apPcPF99o78g-1; Thu, 13 Oct 2022 05:16:25 -0400 X-MC-Unique: pkM7bIR4P-apPcPF99o78g-1 Received: by mail-wm1-f70.google.com with SMTP id g8-20020a05600c4ec800b003b4bcbdb63cso835422wmq.7 for ; Thu, 13 Oct 2022 02:16:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=c1PougXwFNeOBx9Qjbr5s56x+6pgJ2sjuaM5Urh09Fk=; b=CYkXur2LydasAXtrtU8O1UkAKsctC7pi8ertSY8/FAAXH2gNpIR+A+CwHcajvEf+Mm W0n7IJv14W475pGuVDb3Q/kXJrQl55karw2VXuVw8Ny9XSGpTKrkaOKEFz08eAwOjIbM Q7XZtQDad5LDtXbLqzwEkcuwC3zY/rEpbtAb8FGVQjvnFOR+XhAmPBxRA67kp4o/LT/q JQm/wQjCqymHI0C+ZJ/++j8C9OLE0Az2MIzyUK4PGP0N7lPHeT/fIhET/k9D1wWUi1gN fuSOTr7M5xXwaFS+9n1QkObeDwLhbMKPFKzdbhkGlEYx6iz6ZX3N8flxLOf6EDaWIwEI Nl9A== X-Gm-Message-State: ACrzQf1eZi6mbdOT3ZHNxEiLfA8KwpZP3qMahEyy3A9MQdIfEoTbMXc7 OnWXipTVDd6HQCKFonXzOO1ebuD6za1ySL0wf1NGcjy5hJDN/c3BaYCI3vWHsRr0W4OdHNNSAQG 63AalumwaYQ2FXafNgCg9WIn475yxXKL03X+LQ0FoLtpnYC2OsWgBF4yhxx3l3l2jTopfVbuZgO CQ X-Received: by 2002:a05:600c:1e88:b0:3c3:ecf:ce3e with SMTP id be8-20020a05600c1e8800b003c30ecfce3emr5656953wmb.15.1665652584207; Thu, 13 Oct 2022 02:16:24 -0700 (PDT) X-Google-Smtp-Source: AMsMyM7lz0WlApvKFq530rS3Ksn4hAAN1MoaF0PVyZiyi2JurSmUe0qN78jbTg3xrD4n6KsUR0fbjQ== X-Received: by 2002:a05:600c:1e88:b0:3c3:ecf:ce3e with SMTP id be8-20020a05600c1e8800b003c30ecfce3emr5656930wmb.15.1665652583965; Thu, 13 Oct 2022 02:16:23 -0700 (PDT) Received: from ovpn-194-196.brq.redhat.com (nat-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id g17-20020a05600c4ed100b003b4ac05a8a4sm5313583wmq.27.2022.10.13.02.16.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Oct 2022 02:16:23 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson Cc: kvm@vger.kernel.org, Paolo Bonzini , Wanpeng Li , Jim Mattson , Maxim Levitsky , Michael Kelley , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 6/6] KVM: selftests: Test Hyper-V invariant TSC control In-Reply-To: References: <20220922143655.3721218-1-vkuznets@redhat.com> <20220922143655.3721218-7-vkuznets@redhat.com> <87v8op6wq3.fsf@ovpn-194-196.brq.redhat.com> Date: Thu, 13 Oct 2022 11:16:22 +0200 Message-ID: <87pmew6q3d.fsf@ovpn-194-196.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Christopherson writes: > On Wed, Oct 12, 2022, Vitaly Kuznetsov wrote: >> Sean Christopherson writes: >> ... >> > Aha! Idea. Assuming none of the MSRs are write-only, what about adding a prep >> > patch to rework this code so that it verifies RDMSR returns what was written when >> > a fault didn't occur. >> > >> >> There is at least one read-only MSR which comes to mind: >> HV_X64_MSR_EOI. > > I assume s/read-only/write-only since it's EOI? > Yes, of course) >> Also, some of the MSRs don't preserve the written value, >> e.g. HV_X64_MSR_RESET which always reads as '0'. > > Hrm, that's annoying. 'Slightly annoying'. In fact, the test never writes anything besides '0' to the MSR as the code is not ready to handle real vCPU reset. I'll leave a TODO note about that. ... > static bool is_write_only_msr(uint32_t msr) > { > return msr == HV_X64_MSR_EOI; > } This is all we need, basically. I'll go with that. -- Vitaly