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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 656A8C433ED for ; Tue, 4 May 2021 21:46:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3796E613BC for ; Tue, 4 May 2021 21:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231756AbhEDVq5 (ORCPT ); Tue, 4 May 2021 17:46:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231478AbhEDVqz (ORCPT ); Tue, 4 May 2021 17:46:55 -0400 Received: from mail-ot1-x32b.google.com (mail-ot1-x32b.google.com [IPv6:2607:f8b0:4864:20::32b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B5E9C06174A for ; Tue, 4 May 2021 14:45:59 -0700 (PDT) Received: by mail-ot1-x32b.google.com with SMTP id u25-20020a0568302319b02902ac3d54c25eso2322403ote.1 for ; Tue, 04 May 2021 14:45:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=4daw9Y4OB39yIbPmv1qSyV0lFSedRBWvMPVCNOlqsp8=; b=YuahOkppk59MZLC7WekMPtBRH1zWw4mEeRTjyXfWHcaFAEoHYyuVEdm8/VPkYC654O b1QkGuK3lh82Q6JJ4hpW+nrfmorwDx5CunnSLrtcPqR7OSJDAt3F3OePcN1EKaKkNZe+ Grdgil++mGs5tb4rOyJ8Lz+vIwRBN9+BykAI/JI066eDtPrv8j0uoQFBFNefCPCZIltq If4Xh0JnegRP8P1123UI8CFoYdMj6+0HRiiFRB7CYVvuHFJ49EwY51SKdQFSJfnAbYHE ZnC1uGHHYmT6QcHm8hmo2gAlHybbUwmAM+EkMFxj1xZZnYxhj6VJs1eYLkhSdRQJAfVn Lpvg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=4daw9Y4OB39yIbPmv1qSyV0lFSedRBWvMPVCNOlqsp8=; b=ef8jV2tT2xLgXBxVdHpEe+0C9/Or/eTcB4zts7d6P+sQUrDf7nSiWpwJQOPRcdjv3e 2Vb+kpD4bEkSTYFR1bbKHXgCEqw28ygtdErAiJizMSoUQCxB4HR2F9M5aOA1t9HH6t26 QJ6PHehzPtPfM7982XJdjMJ/2BxA4QwWI2jvGMJSiNiiMvvaltE0a/L4grAlqv77PIx3 OK0MYOsiKhfXm37Q87jI7O/hD2ajuiJJ04rL3oAV5mDRYbgWFx/h/1//wgjRTV1kjU6j NK7zS/IP+PTeWcPpJeLypRsSUPkjtG6q8V25viB1cqdZ105jMoQvo2TEpnP1NGIsvM2y Iosw== X-Gm-Message-State: AOAM531Ow4A6dV5RQk12xttu3mcGoRTPYN15Lk3Iqw66mgDWdH/HjDhu ePpPPi+lbI5k1DAeZd1iHFwFxkPBKwAZhwEEebGHzg== X-Google-Smtp-Source: ABdhPJztXVSdXEkoqT3D2wPGFa8u15RwEty3GSdnIbvfUJ4PWmDHPCq3rJvSjQ3gJl1fT/PD4gLTEsmY7DzIesU+Ptw= X-Received: by 2002:a05:6830:16c8:: with SMTP id l8mr21021609otr.56.1620164758579; Tue, 04 May 2021 14:45:58 -0700 (PDT) MIME-Version: 1.0 References: <20210504171734.1434054-1-seanjc@google.com> <20210504171734.1434054-4-seanjc@google.com> In-Reply-To: <20210504171734.1434054-4-seanjc@google.com> From: Jim Mattson Date: Tue, 4 May 2021 14:45:47 -0700 Message-ID: Subject: Re: [PATCH 03/15] KVM: SVM: Inject #UD on RDTSCP when it should be disabled in the guest To: Sean Christopherson Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Joerg Roedel , kvm list , LKML , Xiaoyao Li , Reiji Watanabe Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 4, 2021 at 10:17 AM Sean Christopherson wrote: > > Intercept RDTSCP to inject #UD if RDTSC is disabled in the guest. > > Note, SVM does not support intercepting RDPID. Unlike VMX's > ENABLE_RDTSCP control, RDTSCP interception does not apply to RDPID. This > is a benign virtualization hole as the host kernel (incorrectly) sets > MSR_TSC_AUX if RDTSCP is supported, and KVM loads the guest's MSR_TSC_AUX > into hardware if RDTSCP is supported in the host, i.e. KVM will not leak > the host's MSR_TSC_AUX to the guest. > > But, when the kernel bug is fixed, KVM will start leaking the host's > MSR_TSC_AUX if RDPID is supported in hardware, but RDTSCP isn't available > for whatever reason. This leak will be remedied in a future commit. > > Fixes: 46896c73c1a4 ("KVM: svm: add support for RDTSCP") > Cc: stable@vger.kernel.org > Signed-off-by: Sean Christopherson > --- ... > @@ -4007,8 +4017,7 @@ static void svm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) > svm->nrips_enabled = kvm_cpu_cap_has(X86_FEATURE_NRIPS) && > guest_cpuid_has(vcpu, X86_FEATURE_NRIPS); > > - /* Check again if INVPCID interception if required */ > - svm_check_invpcid(svm); > + svm_recalc_instruction_intercepts(vcpu, svm); Does the right thing happen here if the vCPU is in guest mode when userspace decides to toggle the CPUID.80000001H:EDX.RDTSCP bit on or off?