From nobody Fri Sep 12 13:40:25 2025 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 06421C6FA99 for ; Sat, 11 Mar 2023 00:47:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230378AbjCKArO (ORCPT ); Fri, 10 Mar 2023 19:47:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229967AbjCKAqz (ORCPT ); Fri, 10 Mar 2023 19:46:55 -0500 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3807713D1F0 for ; Fri, 10 Mar 2023 16:46:36 -0800 (PST) Received: by mail-pf1-x44a.google.com with SMTP id x137-20020a62868f000000b0060017d68643so3624784pfd.18 for ; Fri, 10 Mar 2023 16:46:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1678495595; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=fG/gctdmsHG4KFmH0rDrimK5SXVIN8L7Kh/kR2GvG5A=; b=BCXSRihXjCF5gcpGEqZASI3X2u2m382eLGuNLXdp9s9FXaM2NnxlLaov/07yvpjiZI d5dc57wxslbohOAxK7jf/NKVwHIt6oyCqizaYjDuIEe518RQDeiCwgkRz6SEh1xibxxX ySlMYp/aC6gazQyrjwOT5yeD6v4xmZdy3az3oJlb3y4CK8bpbPOhydZ7ceuCu9o9Huz+ WtTW8lcLsuNoak4HCLCQKkZsigrLQu+oQDdqSWBVFk+7C+frapYtH+PegbRXJIXk+q4c D7YI+dZaAvhESpu2jak5vyM8eTXpPHNXsdv1vtNYC6FHKPnU6WPGLLsvDasDULfj7KX9 wtlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678495595; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=fG/gctdmsHG4KFmH0rDrimK5SXVIN8L7Kh/kR2GvG5A=; b=ypxt8vDbAbbbnPNH7LGcw4aZGxU3k+bam/vLaZ/u84UoKKdOd1JtHYohqYjS20+QiK a+y8LVDNc1YWXq1DJ5eJztYHT2JQKSigfJl/pyJvOgWy20CoTw5CVxlRfPG3Uh6Wmpps OhYlngdE9czCss9F2nGHLGuYE0mNzCv4NCj1kKYAFJTIrA/m0UENccs/JE/GC31Hwybi UkYvuu4AABg4gPJuE7nzEV586paDRAsgrQ1zmtoGYfuV1acAcLS/TtO37i4Rx5StSf6h I9jw7/duWm2n1KWCR8MM4W7TK1pXcRSRmTH/m+o4kUKmXEmDo9JJFxmrfeJeAgeMb6MT DCAg== X-Gm-Message-State: AO0yUKUnhVnV7DlIacxxDUR6rgh04CY1IG5v7bZE3gkbWt+qqXE2AHos d9r24MxhUo+Uu6BQubfpF3GtRp1u1Qo= X-Google-Smtp-Source: AK7set/8k4ZuMdVVQdkcEV/wb/yLxhP6jK2ME2RuLadTBBF5FTif/SapvdPl8BOgE6/fCrXKesQjcqO3wpo= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a62:8247:0:b0:5a8:bdd2:f99c with SMTP id w68-20020a628247000000b005a8bdd2f99cmr11215844pfd.1.1678495595379; Fri, 10 Mar 2023 16:46:35 -0800 (PST) Reply-To: Sean Christopherson Date: Fri, 10 Mar 2023 16:46:04 -0800 In-Reply-To: <20230311004618.920745-1-seanjc@google.com> Mime-Version: 1.0 References: <20230311004618.920745-1-seanjc@google.com> X-Mailer: git-send-email 2.40.0.rc1.284.g88254d51c5-goog Message-ID: <20230311004618.920745-8-seanjc@google.com> Subject: [PATCH v3 07/21] KVM: x86/pmu: WARN and bug the VM if PMU is refreshed after vCPU has run From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Like Xu , Yu Zhang Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Now that KVM disallows changing feature MSRs, i.e. PERF_CAPABILITIES, after running a vCPU, WARN and bug the VM if the PMU is refreshed after the vCPU has run. Note, KVM has disallowed CPUID updates after running a vCPU since commit feb627e8d6f6 ("KVM: x86: Forbid KVM_SET_CPUID{,2} after KVM_RUN"), i.e. PERF_CAPABILITIES was the only remaining way to trigger a PMU refresh after KVM_RUN. Cc: Like Xu Signed-off-by: Sean Christopherson --- arch/x86/kvm/pmu.c | 3 +++ arch/x86/kvm/x86.c | 10 +++++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 612e6c70ce2e..7e974c4e61b0 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -589,6 +589,9 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_d= ata *msr_info) */ void kvm_pmu_refresh(struct kvm_vcpu *vcpu) { + if (KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm)) + return; + static_call(kvm_x86_pmu_refresh)(vcpu); } =20 diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 219492cd887e..93a7302e4fc3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3625,9 +3625,17 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct= msr_data *msr_info) if (data & ~kvm_caps.supported_perf_cap) return 1; =20 + /* + * Note, this is not just a performance optimization! KVM + * disallows changing feature MSRs after the vCPU has run; PMU + * refresh will bug the VM if called after the vCPU has run. + */ + if (vcpu->arch.perf_capabilities =3D=3D data) + break; + vcpu->arch.perf_capabilities =3D data; kvm_pmu_refresh(vcpu); - return 0; + break; case MSR_EFER: return set_efer(vcpu, msr_info); case MSR_K7_HWCR: --=20 2.40.0.rc1.284.g88254d51c5-goog