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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 701BAC433C1 for ; Tue, 23 Mar 2021 08:46:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37A67619B1 for ; Tue, 23 Mar 2021 08:46:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229944AbhCWIpc (ORCPT ); Tue, 23 Mar 2021 04:45:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39689 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229622AbhCWIpW (ORCPT ); Tue, 23 Mar 2021 04:45:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616489122; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=bWgjxBic5KxGRp4l3xszbSrPWge16zEazFDHmYAecQY=; b=QJa9LbTnr66aQ3lJZJXrICN6xEe/4IaU2gS9B50qya8qwPqqTSzKIDq2GrN2zmxUGmfS/R 6L69Jdt22b5IHn56H3185TOenK9YcrmXG8bDWSN7llh1apjUXrz3XjF86OikyZPd1xhIIK LiyS62cP5D2fu7s0SSi2SlyD1MZxErY= 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-207-ODt21XKFOvWp4gOtUumWzA-1; Tue, 23 Mar 2021 04:45:20 -0400 X-MC-Unique: ODt21XKFOvWp4gOtUumWzA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D2E7183DD26; Tue, 23 Mar 2021 08:45:18 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.40.195.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 43A3A1F7; Tue, 23 Mar 2021 08:45:16 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Wei Huang , Joerg Roedel , linux-kernel@vger.kernel.org Subject: [PATCH] KVM: x86/vPMU: Forbid writing to MSR_F15H_PERF MSRs when guest doesn't have X86_FEATURE_PERFCTR_CORE Date: Tue, 23 Mar 2021 09:45:15 +0100 Message-Id: <20210323084515.1346540-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org MSR_F15H_PERF_CTL0-5, MSR_F15H_PERF_CTR0-5 MSRs are only available when X86_FEATURE_PERFCTR_CORE CPUID bit was exposed to the guest. KVM, however, allows these MSRs unconditionally because kvm_pmu_is_valid_msr() -> amd_msr_idx_to_pmc() check always passes and because kvm_pmu_set_msr() -> amd_pmu_set_msr() doesn't fail. In case of a counter (CTRn), no big harm is done as we only increase internal PMC's value but in case of an eventsel (CTLn), we go deep into perf internals with a non-existing counter. Note, kvm_get_msr_common() just returns '0' when these MSRs don't exist and this also seems to contradict architectural behavior which is #GP (I did check one old Opteron host) but changing this status quo is a bit scarier. Signed-off-by: Vitaly Kuznetsov --- arch/x86/kvm/svm/pmu.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c index 035da07500e8..fdf587f19c5f 100644 --- a/arch/x86/kvm/svm/pmu.c +++ b/arch/x86/kvm/svm/pmu.c @@ -98,6 +98,8 @@ static enum index msr_to_index(u32 msr) static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr, enum pmu_type type) { + struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu); + switch (msr) { case MSR_F15H_PERF_CTL0: case MSR_F15H_PERF_CTL1: @@ -105,6 +107,9 @@ static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr, case MSR_F15H_PERF_CTL3: case MSR_F15H_PERF_CTL4: case MSR_F15H_PERF_CTL5: + if (!guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE)) + return NULL; + fallthrough; case MSR_K7_EVNTSEL0 ... MSR_K7_EVNTSEL3: if (type != PMU_TYPE_EVNTSEL) return NULL; @@ -115,6 +120,9 @@ static inline struct kvm_pmc *get_gp_pmc_amd(struct kvm_pmu *pmu, u32 msr, case MSR_F15H_PERF_CTR3: case MSR_F15H_PERF_CTR4: case MSR_F15H_PERF_CTR5: + if (!guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE)) + return NULL; + fallthrough; case MSR_K7_PERFCTR0 ... MSR_K7_PERFCTR3: if (type != PMU_TYPE_COUNTER) return NULL; -- 2.30.2