From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9FAFE3D45EA; Mon, 27 Jul 2026 19:32:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785180730; cv=none; b=dMRTCT3anmFVbhnGtxt7O7HcJbMqfIWng/cp7VPJSFA5K7tA0mU6hu0Ve9AcyYUJteoRI62IW8uYg7ARBGO3cV7SB2Zt1dnn72mru0lr3LbpfVCzuoxuHDJHyxBtpHE41ThEOwi0Ghz1/R1gUy/N38GiFyiKuQGRrajyQhTxXis= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785180730; c=relaxed/simple; bh=OIpgGHMD61ck7m1vwTrtcDDodUwOEUis5qKg+8LrYGs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=thWZKlegnbmzqWB4AFtPbRKUsiAMwTa5cLCEtmPSr7IrhDuY95JjwZVnzrePuQsqgcJdW72pUSp3kmimjBy/rXfv9r3UWv8/kqLNtNh0J+sc0VgHMJfpGjmEiJGgTJRCyOs3+jPxRqdvDCyoHDgNaZ+pIE/udz+sHNiHqUBSXjE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Ec7V6I88; arc=none smtp.client-ip=192.198.163.15 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Ec7V6I88" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1785180727; x=1816716727; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=OIpgGHMD61ck7m1vwTrtcDDodUwOEUis5qKg+8LrYGs=; b=Ec7V6I88D/ydhrG0JXI7sKTli2jQm8eoxhq2T7Aye+9+1Wi2A9zMyd4z R8wSIU4c4zB3m4UGKx3FOrn+kY+5PgMX2OB0Z4WZWvi5A1DG4VJiJXhyF w7U8iklpvTkcuVQ4PG5+1PnhZqmjvoJKZGjdsQvYhpitzDuQFw9YVAMYN +LVxVcA8jWJjzpIBNM7CoIV2V3Zf79NhX1y1TwsKUKMSjNEGZQT4aOAfD /TEKdV6a5PUn3545U0voPrfJ6VUNQLjNJ6ZKVRqseiXKKBTLDCwUgukkA 5RrYOcCNYdeIlSe789fE+8EuUUbIw9r62Oxj3ifBcZ0ETBVUqcbNwVz9p g==; X-CSE-ConnectionGUID: +/BF9YvZRWCl3XfbeJrOQQ== X-CSE-MsgGUID: vshnNY6dSB2PuI7DIRgzAg== X-IronPort-AV: E=McAfee;i="6800,10657,11858"; a="85876710" X-IronPort-AV: E=Sophos;i="6.25,189,1779174000"; d="scan'208";a="85876710" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jul 2026 12:32:00 -0700 X-CSE-ConnectionGUID: WfC5YUwFRRqtLA770XEcZA== X-CSE-MsgGUID: N9eXSM2lTH6VJ3ei+LP7Cg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,189,1779174000"; d="scan'208";a="289451041" Received: from 9cc2c43eec6b.jf.intel.com ([10.54.77.29]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Jul 2026 12:32:00 -0700 From: Zide Chen To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, Jim Mattson , Andi Kleen , linux-kernel@vger.kernel.org, Mingwei Zhang , Zide Chen , Das Sandipan , Shukla Manali , Dapeng Mi , Falcon Thomas , Xudong Hao Subject: [PATCH v7 5/9] KVM: x86/pmu: Support PERF_METRICS MSR in mediated vPMU Date: Mon, 27 Jul 2026 12:21:27 -0700 Message-ID: <20260727192131.582105-6-zide.chen@intel.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260727192131.582105-1-zide.chen@intel.com> References: <20260727192131.582105-1-zide.chen@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Dapeng Mi Bit 15 in IA32_PERF_CAPABILITIES indicates that the CPU provides built-in support for Topdown Microarchitecture Analysis (TMA) L1 metrics via the IA32_PERF_METRICS MSR. Expose this capability only when mediated vPMU is enabled, as emulating IA32_PERF_METRICS in the legacy vPMU model is impractical. Pass IA32_PERF_METRICS through to the guest only when mediated vPMU is enabled and bit 15 is set in guest IA32_PERF_CAPABILITIES. Allow kvm_pmu_{get,set}_msr() to handle this MSR for host accesses. Save and restore this MSR on host/guest PMU context switches so that host PMU activity does not clobber the guest value, and guest state is not leaked into the host. Signed-off-by: Dapeng Mi Signed-off-by: Zide Chen --- v7: - Clear bit 48 in global_ctrl_rsvd instead of explicitly clearing it in global_status_rsvd, allowing it to propagate through the assignment from global_ctrl_rsvd. - Add comments documenting the all-zero PERF_METRICS/FC3 write-order exception. - Add nested_vmx_merge_msr_bitmaps_rw(MSR_PERF_METRICS); v5: - Remove host_initiated check in set/get MSR handlers. v4: - Remove WARN_ON_ONCE() and simply reject the guest accesses by checking host_initiated. (Sashiko) - Passthru MSR_PERF_METRICS only if has_mediated_pmu is true. (Sashiko) - Remove the redundant !! in vcpu_has_perf_metrics(). v3: - Replace WARN_ON() with WARN_ON_ONCE(). (Dapeng) - Add comments to explain why we don't validate writes on PERF_METRICS. --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/include/asm/msr-index.h | 1 + arch/x86/kvm/msrs.c | 6 +++++- arch/x86/kvm/pmu.h | 5 +++++ arch/x86/kvm/vmx/nested.c | 2 ++ arch/x86/kvm/vmx/pmu_intel.c | 34 ++++++++++++++++++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 7 +++++++ 7 files changed, 55 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index e663bdfb1d02..a90bce8552f9 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -581,6 +581,7 @@ struct kvm_pmu { u64 global_status_rsvd; u64 reserved_bits; u64 raw_event_mask; + u64 perf_metrics; struct kvm_pmc gp_counters[KVM_MAX_NR_GP_COUNTERS]; struct kvm_pmc fixed_counters[KVM_MAX_NR_FIXED_COUNTERS]; diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 18c4be75e927..fdcaeb6c8352 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -331,6 +331,7 @@ #define PERF_CAP_PEBS_FORMAT 0xf00 #define PERF_CAP_FW_WRITES BIT_ULL(13) #define PERF_CAP_PEBS_BASELINE BIT_ULL(14) +#define PERF_CAP_PERF_METRICS BIT_ULL(15) #define PERF_CAP_PEBS_TIMING_INFO BIT_ULL(17) #define PERF_CAP_PEBS_MASK (PERF_CAP_PEBS_TRAP | PERF_CAP_ARCH_REG | \ PERF_CAP_PEBS_FORMAT | PERF_CAP_PEBS_BASELINE | \ diff --git a/arch/x86/kvm/msrs.c b/arch/x86/kvm/msrs.c index 3bf42d90ad14..c751a8dbd45d 100644 --- a/arch/x86/kvm/msrs.c +++ b/arch/x86/kvm/msrs.c @@ -230,7 +230,7 @@ static const u32 msrs_to_save_pmu[] = { MSR_ARCH_PERFMON_FIXED_CTR0, MSR_ARCH_PERFMON_FIXED_CTR1, MSR_ARCH_PERFMON_FIXED_CTR2, MSR_ARCH_PERFMON_FIXED_CTR3, MSR_CORE_PERF_FIXED_CTR_CTRL, MSR_CORE_PERF_GLOBAL_STATUS, - MSR_CORE_PERF_GLOBAL_CTRL, + MSR_CORE_PERF_GLOBAL_CTRL, MSR_PERF_METRICS, MSR_IA32_PEBS_ENABLE, MSR_IA32_DS_AREA, MSR_PEBS_DATA_CFG, /* This part of MSRs should match KVM_MAX_NR_INTEL_GP_COUNTERS. */ @@ -2625,6 +2625,10 @@ static void kvm_probe_msr_to_save(u32 msr_index) intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2)) return; break; + case MSR_PERF_METRICS: + if (!(kvm_caps.supported_perf_cap & PERF_CAP_PERF_METRICS)) + return; + break; case MSR_ARCH_PERFMON_PERFCTR0 ... MSR_ARCH_PERFMON_PERFCTR0 + KVM_MAX_NR_GP_COUNTERS - 1: if (msr_index - MSR_ARCH_PERFMON_PERFCTR0 >= diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h index 1b2f66a2e915..3066cade5790 100644 --- a/arch/x86/kvm/pmu.h +++ b/arch/x86/kvm/pmu.h @@ -279,6 +279,11 @@ static inline u64 kvm_vcpu_get_perf_caps(struct kvm_vcpu *vcpu) return vcpu->arch.perf_capabilities; } +static inline bool kvm_vcpu_has_perf_metrics(struct kvm_vcpu *vcpu) +{ + return kvm_vcpu_get_perf_caps(vcpu) & PERF_CAP_PERF_METRICS; +} + void kvm_pmu_deliver_pmi(struct kvm_vcpu *vcpu); int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned pmc, u64 *data); int kvm_pmu_check_rdpmc_early(struct kvm_vcpu *vcpu, unsigned int idx); diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index b5460de4b1a7..56a9931d6994 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -717,6 +717,8 @@ static void nested_vmx_merge_pmu_msr_bitmaps(struct kvm_vcpu *vcpu, nested_vmx_merge_msr_bitmaps_rw(MSR_CORE_PERF_GLOBAL_CTRL); nested_vmx_merge_msr_bitmaps_read(MSR_CORE_PERF_GLOBAL_STATUS); nested_vmx_merge_msr_bitmaps_write(MSR_CORE_PERF_GLOBAL_OVF_CTRL); + + nested_vmx_merge_msr_bitmaps_rw(MSR_PERF_METRICS); } /* diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index a9202737debe..a2845d398377 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -189,6 +189,8 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr) switch (msr) { case MSR_CORE_PERF_FIXED_CTR_CTRL: return kvm_pmu_has_perf_global_ctrl(pmu); + case MSR_PERF_METRICS: + return kvm_vcpu_has_perf_metrics(vcpu); case MSR_IA32_PEBS_ENABLE: ret = kvm_vcpu_get_perf_caps(vcpu) & PERF_CAP_PEBS_FORMAT; break; @@ -346,6 +348,9 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) case MSR_CORE_PERF_FIXED_CTR_CTRL: msr_info->data = pmu->fixed_ctr_ctrl; break; + case MSR_PERF_METRICS: + msr_info->data = pmu->perf_metrics; + break; case MSR_IA32_PEBS_ENABLE: msr_info->data = pmu->pebs_enable; break; @@ -395,6 +400,14 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) if (pmu->fixed_ctr_ctrl != data) reprogram_fixed_counters(pmu, data); break; + case MSR_PERF_METRICS: + /* + * Bits [63:32] are ignored on hardware that supports only + * level-1 metrics, but may be valid on hardware that supports + * level-2 metrics. Preserve guest writes verbatim. + */ + pmu->perf_metrics = data; + break; case MSR_IA32_PEBS_ENABLE: if (data & pmu->pebs_enable_rsvd) return 1; @@ -577,6 +590,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) counter_rsvd = ~((BIT_ULL(pmu->nr_arch_gp_counters) - 1) | ((BIT_ULL(pmu->nr_arch_fixed_counters) - 1) << KVM_FIXED_PMC_BASE_IDX)); pmu->global_ctrl_rsvd = counter_rsvd; + if (perf_capabilities & PERF_CAP_PERF_METRICS) + pmu->global_ctrl_rsvd &= ~GLOBAL_CTRL_EN_PERF_METRICS; /* * GLOBAL_STATUS and GLOBAL_OVF_CONTROL (a.k.a. GLOBAL_STATUS_RESET) @@ -633,6 +648,9 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu) static void intel_pmu_reset(struct kvm_vcpu *vcpu) { + struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); + + pmu->perf_metrics = 0; intel_pmu_release_guest_lbr_event(vcpu); } @@ -804,6 +822,9 @@ static void intel_mediated_pmu_load(struct kvm_vcpu *vcpu) struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); u64 global_status, toggle; + if (kvm_vcpu_has_perf_metrics(vcpu)) + wrmsrq(MSR_PERF_METRICS, pmu->perf_metrics); + rdmsrq(MSR_CORE_PERF_GLOBAL_STATUS, global_status); toggle = pmu->global_status ^ global_status; if (global_status & toggle) @@ -832,6 +853,19 @@ static void intel_mediated_pmu_put(struct kvm_vcpu *vcpu) */ if (pmu->fixed_ctr_ctrl_hw) wrmsrq(MSR_CORE_PERF_FIXED_CTR_CTRL, 0); + + if (kvm_vcpu_has_perf_metrics(vcpu)) { + pmu->perf_metrics = rdpmc(INTEL_PMC_FIXED_RDPMC_METRICS); + /* + * The SDM requires restoring fixed counter 3 before + * PERF_METRICS. However, this path writes 0 to PERF_METRICS + * before fixed counter 3. For this all-zero case, the + * resulting hardware state is therefore the same regardless + * of write order. + */ + if (pmu->perf_metrics) + wrmsrq(MSR_PERF_METRICS, 0); + } } struct kvm_pmu_ops intel_pmu_ops __initdata = { diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 08c70f94ae39..c93ba17838c4 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -4274,6 +4274,10 @@ static void vmx_recalc_pmu_msr_intercepts(struct kvm_vcpu *vcpu) MSR_TYPE_RW, intercept); vmx_set_intercept_for_msr(vcpu, MSR_CORE_PERF_GLOBAL_OVF_CTRL, MSR_TYPE_RW, intercept); + + intercept = !has_mediated_pmu || !kvm_vcpu_has_perf_metrics(vcpu); + vmx_set_intercept_for_msr(vcpu, MSR_PERF_METRICS, + MSR_TYPE_RW, intercept); } static void vmx_recalc_msr_intercepts(struct kvm_vcpu *vcpu) @@ -8096,6 +8100,9 @@ static __init u64 vmx_get_perf_capabilities(void) perf_cap &= ~PERF_CAP_PEBS_BASELINE; } + if (enable_mediated_pmu) + perf_cap |= kvm_host.perf_capabilities & PERF_CAP_PERF_METRICS; + return perf_cap; } -- 2.54.0