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[2620:137:e000::1:20]) by mx.google.com with ESMTP id q24-20020a656a98000000b004def536009dsi3357922pgu.180.2023.02.09.16.33.32; Thu, 09 Feb 2023 16:33:45 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=eFeXbUZs; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230320AbjBJAcf (ORCPT + 99 others); Thu, 9 Feb 2023 19:32:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230236AbjBJAcR (ORCPT ); Thu, 9 Feb 2023 19:32:17 -0500 Received: from mail-pj1-x1049.google.com (mail-pj1-x1049.google.com [IPv6:2607:f8b0:4864:20::1049]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1EFA6E880 for ; Thu, 9 Feb 2023 16:32:03 -0800 (PST) Received: by mail-pj1-x1049.google.com with SMTP id mi18-20020a17090b4b5200b00230e56d5a44so1702774pjb.1 for ; Thu, 09 Feb 2023 16:32:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; 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=lmrHsEd1kvbCEq2I68uT6iSRNvZfXrvkq6sDzsXiSd8=; b=eFeXbUZsLbfNmRG2IC3K5Td95hJyMIBDyhLJbX7KOnO7j9qBQs4ffh7MH+DTeFYR66 GPxjZuzdYJs926CDgjuSJrEU4CZlAnm5YBPHzTt61cE605mDF0frD062wM7KlwwBlT5R oD2TMUDVjJy1Xs9xM0JOmDVSNaPLJj7wphE07o3YIeYrupB8gBOrRAKCEFErIyMXJBux s6tysAlHtj05f2QLU5bIke6dc1SeNxA5u+vZ6zppv5bzec2Cgae0Sk4Ttc3eMgkNWGMy UZt09U2thAEQDY52kwh0mv/0Ie1OwtkxyTfqTMmArhrrn68GXeX0glrtW8tPE1/Yc8fp bYFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=lmrHsEd1kvbCEq2I68uT6iSRNvZfXrvkq6sDzsXiSd8=; b=RqszdTmFyguA3l5Bf0q27G1v+LCW5oUwA1frz05PAxYzrZsa0JldUt/0dSaTkv7rOP za3HVhseWby6N8URrFAf+AJQwupuQ/oYmm0QYLllMG7dwq7bx/Zuyz5uAuX5wVc8SncK W0y0fLjw2SVKM9IO46pH+AVjy5xe9qa7Vnc871CSmi7Ah4Pb9fFDQOwoYJBaRwB0dk3z +Dxy0x+XjaZhQpuL1MhU+0RJ8cdZyXKwyzmtSksVww/1XQKtSvSXxyJdEAX2apaUmNKB /X1eKURL9s/QFxwVGZZBdKLAQLNSzPTrXI7J39Z02r0OzpqYOqdmwPuzyRZbmrgzxj4H sOXw== X-Gm-Message-State: AO0yUKX+WgP0bPeDAvmglp5UVnx1U8N5KB0vsb0g78XvSLN05xw808F/ NnKmkjv1mzM6GcK4agyskcFgEFBJvko= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a63:b346:0:b0:4df:c991:3a74 with SMTP id x6-20020a63b346000000b004dfc9913a74mr2450713pgt.94.1675989122972; Thu, 09 Feb 2023 16:32:02 -0800 (PST) Reply-To: Sean Christopherson Date: Fri, 10 Feb 2023 00:31:34 +0000 In-Reply-To: <20230210003148.2646712-1-seanjc@google.com> Mime-Version: 1.0 References: <20230210003148.2646712-1-seanjc@google.com> X-Mailer: git-send-email 2.39.1.581.gbfd45094c4-goog Message-ID: <20230210003148.2646712-8-seanjc@google.com> Subject: [PATCH v2 07/21] KVM: x86/pmu: Zero out LBR capabilities during PMU refresh From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Like Xu X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1757402078224911136?= X-GMAIL-MSGID: =?utf-8?q?1757402078224911136?= Zero out the LBR capabilities during PMU refresh to avoid exposing LBRs to the guest against userspace's wishes. If userspace modifies the guest's CPUID model or invokes KVM_CAP_PMU_CAPABILITY to disable vPMU after an initial KVM_SET_CPUID2, but before the first KVM_RUN, KVM will retain the previous LBR info due to bailing before refreshing the LBR descriptor. Note, this is a very theoretical bug, there is no known use case where a VMM would deliberately enable the vPMU via KVM_SET_CPUID2, and then later disable the vPMU. Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/pmu_intel.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index e8a3be0b9df9..d889bb2a1de5 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -531,6 +531,16 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) pmu->pebs_enable_mask = ~0ull; pmu->pebs_data_cfg_mask = ~0ull; + memset(&lbr_desc->records, 0, sizeof(lbr_desc->records)); + + /* + * Setting passthrough of LBR MSRs is done only in the VM-Entry loop, + * and PMU refresh is disallowed after the vCPU has run, i.e. this code + * should never be reached while KVM is passing through MSRs. + */ + if (KVM_BUG_ON(lbr_desc->msr_passthrough, vcpu->kvm)) + return; + entry = kvm_find_cpuid_entry(vcpu, 0xa); if (!entry || !vcpu->kvm->arch.enable_pmu) return;