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X-CSE-ConnectionGUID: VPk+iYG6TSyq1F9aJPtWiQ== X-CSE-MsgGUID: Xm3tdSD5T6es1yKVthdgZw== X-IronPort-AV: E=McAfee;i="6800,10657,11832"; a="83489357" X-IronPort-AV: E=Sophos;i="6.24,233,1774335600"; d="scan'208";a="83489357" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jun 2026 19:19:34 -0700 X-CSE-ConnectionGUID: vVrurESgQJqFukjyfeyZtg== X-CSE-MsgGUID: OeGpE3rVRC2VmxqVB1atQA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,233,1774335600"; d="scan'208";a="252270232" Received: from dapengmi-mobl1.ccr.corp.intel.com (HELO [10.124.232.65]) ([10.124.232.65]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jun 2026 19:19:32 -0700 Message-ID: <82a6fffa-3fac-4444-806b-536b3a98c9f0@linux.intel.com> Date: Tue, 30 Jun 2026 10:19:29 +0800 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 4/8] KVM: x86/pmu: Snapshot host IA32_PERF_CAPABILITIES in kvm_host To: Zide Chen , Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Jim Mattson , Mingwei Zhang , Das Sandipan , Shukla Manali , Falcon Thomas , Xudong Hao References: <20260629231938.15129-1-zide.chen@intel.com> <20260629231938.15129-5-zide.chen@intel.com> Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: <20260629231938.15129-5-zide.chen@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Reviewed-by: Dapeng Mi On 6/30/2026 7:19 AM, Zide Chen wrote: > From: Mingwei Zhang > > Cache the unadulterated snapshot of perf_capabilities so that KVM can > compare guest vPMU capabilities against raw hardware capabilities. > > For example, if the host supports PERF_METRICS but it is not configured > for the guest, KVM can use it to determine that RDPMC accesses must be > intercepted. > > Signed-off-by: Mingwei Zhang > Signed-off-by: Zide Chen > --- > v5: new patch. > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/vmx/vmx.c | 8 ++------ > arch/x86/kvm/x86.c | 4 ++++ > 3 files changed, 7 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index dc9e4e8bfc07..80f638588bf7 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -347,6 +347,7 @@ struct kvm_host_values { > u64 xss; > u64 s_cet; > u64 arch_capabilities; > + u64 perf_capabilities; > }; > extern struct kvm_host_values kvm_host; > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index aded7039bd3e..b736b9ff965b 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -8050,14 +8050,10 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) > static __init u64 vmx_get_perf_capabilities(void) > { > u64 perf_cap = PERF_CAP_FW_WRITES; > - u64 host_perf_cap = 0; > > if (!enable_pmu) > return 0; > > - if (boot_cpu_has(X86_FEATURE_PDCM)) > - rdmsrq(MSR_IA32_PERF_CAPABILITIES, host_perf_cap); > - > if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR) && > !enable_mediated_pmu) { > x86_perf_get_lbr(&vmx_lbr_caps); > @@ -8070,11 +8066,11 @@ static __init u64 vmx_get_perf_capabilities(void) > if (!vmx_lbr_caps.has_callstack) > memset(&vmx_lbr_caps, 0, sizeof(vmx_lbr_caps)); > else if (vmx_lbr_caps.nr) > - perf_cap |= host_perf_cap & PERF_CAP_LBR_FMT; > + perf_cap |= kvm_host.perf_capabilities & PERF_CAP_LBR_FMT; > } > > if (vmx_pebs_supported()) { > - perf_cap |= host_perf_cap & PERF_CAP_PEBS_MASK; > + perf_cap |= kvm_host.perf_capabilities & PERF_CAP_PEBS_MASK; > > /* > * Disallow adaptive PEBS as it is functionally broken, can be > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 8dbc0fa302a8..8e775855f9be 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7032,6 +7032,10 @@ int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops) > if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES)) > rdmsrq(MSR_IA32_ARCH_CAPABILITIES, kvm_host.arch_capabilities); > > + if (boot_cpu_has(X86_FEATURE_PDCM)) > + rdmsrq_safe(MSR_IA32_PERF_CAPABILITIES, > + &kvm_host.perf_capabilities); > + > WARN_ON_ONCE(kvm_nr_uret_msrs); > > r = ops->hardware_setup();