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 2E992C43334 for ; Tue, 12 Jul 2022 15:34:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234162AbiGLPeB (ORCPT ); Tue, 12 Jul 2022 11:34:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234152AbiGLPdt (ORCPT ); Tue, 12 Jul 2022 11:33:49 -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 ESMTP id 5A468FD36 for ; Tue, 12 Jul 2022 08:33:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657640025; 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=QvXvgma6mjwjAWHd6+YYVyH2hz1GPZg9VsvRaOcyslY=; b=aUg2HtlsGDEKV3tmXd8AnhOmeNNNbXF7bKaE8skISow+dVn6IXbtq0bNNEQAYiv1pscB3P /x1S7EU5C86JMiryfoiHQs4r/vqc5aTq5hZvAvqSs1u0sbJHMuHJLl8B6HlZElg8+AC59r 97rhNSxKZboaIXF1LmsepE/s6+J+Z6A= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-396-aYU8f4X4MR6iRCH_zjuw8Q-1; Tue, 12 Jul 2022 11:33:42 -0400 X-MC-Unique: aYU8f4X4MR6iRCH_zjuw8Q-1 Received: by mail-wr1-f71.google.com with SMTP id i9-20020adfa509000000b0021d865ce5e3so1509046wrb.6 for ; Tue, 12 Jul 2022 08:33:42 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version:content-transfer-encoding; bh=QvXvgma6mjwjAWHd6+YYVyH2hz1GPZg9VsvRaOcyslY=; b=dQlWjTTWIvmSUpFrRUvxNz4Y20JSDK5jampSPjzLC+3oitonDu32RpEOi6qDp5ei93 U6PbeVKaH1lFsAKOd+7Xouo6pnmumf5gueVP2OhqlSS6HJV/vHry5j2AfXKk2gkYMjIZ f1U9jIVKjo1uFhNrhEFGnasv6UdjbA6VnabjxdLta/YsWGp9wChLvnT7ewtngwoQNVS+ Uq7Rhn53vM4jmq69Yz4bUksxsc8beXLOv/NkllAvXUoKpGq2xZy76r0OURrfsxy6PV2n 2JOQAUqw0bNoyJe3mmIOZFlolcUI+nBmKgJGBu5pzgvd3Q3m7z5A4eGaY+qlhl6OyH7Q zL1w== X-Gm-Message-State: AJIora+TElBV9sHy1Uju7hF2JYTVkZsADgJffNrDNOP6dDBecRJkTdlX MY1j1IVvjoDK1xF7/3fuIqZvTzDE49U+IY8Xv8IiKZIee6AocOCPuKlGGVuSSyrzgOoxL4Wto0a rd3yXnWWGlLXp X-Received: by 2002:a5d:584d:0:b0:21d:b7f8:7d19 with SMTP id i13-20020a5d584d000000b0021db7f87d19mr732904wrf.260.1657640021515; Tue, 12 Jul 2022 08:33:41 -0700 (PDT) X-Google-Smtp-Source: AGRyM1vsohtsRezHd+K1mxMoD6DDUTSf09YMJkQwLUwuJfnXvRlCJvmmUonwXDMUPJZckhIQXtJWnA== X-Received: by 2002:a5d:584d:0:b0:21d:b7f8:7d19 with SMTP id i13-20020a5d584d000000b0021db7f87d19mr732881wrf.260.1657640021211; Tue, 12 Jul 2022 08:33:41 -0700 (PDT) Received: from fedora (nat-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id b1-20020adfee81000000b0021bbdc3375fsm8651134wro.68.2022.07.12.08.33.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Jul 2022 08:33:40 -0700 (PDT) From: Vitaly Kuznetsov To: Maxim Levitsky , kvm@vger.kernel.org, Paolo Bonzini , Sean Christopherson Cc: Wanpeng Li , Jim Mattson , linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: nVMX: Always enable TSC scaling for L2 when it was enabled for L1 In-Reply-To: References: <20220712135009.952805-1-vkuznets@redhat.com> Date: Tue, 12 Jul 2022 17:33:39 +0200 Message-ID: <871quqpcq4.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Maxim Levitsky writes: > On Tue, 2022-07-12 at 15:50 +0200, Vitaly Kuznetsov wrote: >> Windows 10/11 guests with Hyper-V role (WSL2) enabled are observed to >> hang upon boot or shortly after when a non-default TSC frequency was >> set for L1. The issue is observed on a host where TSC scaling is >> supported. The problem appears to be that Windows doesn't use TSC >> frequency ^^^ scaling ^^^ >> for its guests even when the feature is advertised and KVM >> filters SECONDARY_EXEC_TSC_SCALING out when creating L2 controls from >> L1's. This leads to L2 running with the default frequency (matching >> host's) while L1 is running with an altered one. > > Ouch. > > I guess that needs a Fixes tag? > > Fixes: d041b5ea93352b ("KVM: nVMX: Enable nested TSC scaling") > I dismissed that because prior to d041b5ea93352b SECONDARY_EXEC_TSC_SCALING was filtered out in nested_vmx_setup_ctls_msrs() but now I think I was wrong, SECONDARY_EXEC_TSC_SCALING was likely kept in VMCS02 regardless of that. Will add in v2. > Also this is thankfully Intel specific, because in AMD you can't enable > TSC scaling - there is just an MSR with default value of 1.0, > which one can change if TSC scaling is supported in CPUID. > > Reviewed-by: Maxim Levitsky Thanks! > Best regards, > Maxim Levitsky > > >>=20 >> Keep SECONDARY_EXEC_TSC_SCALING in secondary exec controls for L2 when >> it was set for L1. TSC_MULTIPLIER is already correctly computed and >> written by prepare_vmcs02(). >>=20 >> Signed-off-by: Vitaly Kuznetsov >> --- >> =C2=A0arch/x86/kvm/vmx/nested.c | 1 - >> =C2=A01 file changed, 1 deletion(-) >>=20 >> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c >> index 778f82015f03..bfa366938c49 100644 >> --- a/arch/x86/kvm/vmx/nested.c >> +++ b/arch/x86/kvm/vmx/nested.c >> @@ -2284,7 +2284,6 @@ static void prepare_vmcs02_early(struct vcpu_vmx *= vmx, struct loaded_vmcs *vmcs0 >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SECONDARY_EXEC_VIRTUAL_= INTR_DELIVERY | >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SECONDARY_EXEC_APIC_REG= ISTER_VIRT | >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SECONDARY_EXEC_ENABLE_V= MFUNC | >> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SECONDARY_EXEC_TSC_SCALING= | >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 SECONDARY_EXEC_DESC); >> =C2=A0 >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0if (nested_cpu_has(vmcs12, > > --=20 Vitaly