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X-CSE-ConnectionGUID: YdCzFwf/SoC9Aehme375eA== X-CSE-MsgGUID: b4Hi0sMDQgO2ILZEJ9kQ5w== X-IronPort-AV: E=McAfee;i="6800,10657,11892"; a="88657317" X-IronPort-AV: E=Sophos;i="6.25,255,1779174000"; d="scan'208";a="88657317" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2026 19:31:03 -0700 X-CSE-ConnectionGUID: /sVRQfwXT8myN3NYbh8NAg== X-CSE-MsgGUID: iiUw0egYQmOtAk0W51td0Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,255,1779174000"; d="scan'208";a="292447406" Received: from dapengmi-mobl1.ccr.corp.intel.com (HELO [10.124.241.239]) ([10.124.241.239]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2026 19:31:00 -0700 Message-ID: <253df5b9-e13a-4d19-aa46-d6432384985e@linux.intel.com> Date: Tue, 1 Sep 2026 10:30:58 +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 v2 04/16] KVM: x86/pmu: Gate BUFFER_OVF reserved bit on guest DS To: Zide Chen , Sean Christopherson , Paolo Bonzini , Peter Zijlstra Cc: kvm@vger.kernel.org, Andi Kleen , Jim Mattson , Stephane Eranian , linux-kernel@vger.kernel.org, Mingwei Zhang , Das Sandipan , Shukla Manali , Xudong Hao References: <20260827223755.143247-1-zide.chen@intel.com> <20260827223755.143247-5-zide.chen@intel.com> Content-Language: en-US From: "Mi, Dapeng" In-Reply-To: <20260827223755.143247-5-zide.chen@intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Reviewed-by: Dapeng Mi On 8/28/2026 6:37 AM, Zide Chen wrote: > global_status_rsvd unconditionally clears GLOBAL_STATUS_BUFFER_OVF > (bit 62), even when the guest does not have X86_FEATURE_DS feature. > Clear it only when guest_cpu_cap_has(vcpu, X86_FEATURE_DS), matching > hardware behavior. > > Fixes: f5132b01386b ("KVM: Expose a version 2 architectural PMU to a guests") > Signed-off-by: Zide Chen > --- > v2: new patch. > --- > arch/x86/kvm/vmx/pmu_intel.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c > index 11c9161dc853..9fdae437e569 100644 > --- a/arch/x86/kvm/vmx/pmu_intel.c > +++ b/arch/x86/kvm/vmx/pmu_intel.c > @@ -576,8 +576,16 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) > ((BIT_ULL(pmu->nr_arch_fixed_counters) - 1) << KVM_FIXED_PMC_BASE_IDX)); > pmu->global_ctrl_rsvd = counter_rsvd; > > - pmu->global_status_rsvd = pmu->global_ctrl_rsvd > - & ~(GLOBAL_STATUS_BUFFER_OVF | GLOBAL_STATUS_COND_CHG); > + /* > + * Layout of bits 48:0 in IA32_PERF_GLOBAL_CTRL is identical to > + * IA32_PERF_GLOBAL_STATUS, but IA32_PERF_GLOBAL_STATUS has additional > + * bits. > + */ > + pmu->global_status_rsvd = pmu->global_ctrl_rsvd; > + if (guest_cpu_cap_has(vcpu, X86_FEATURE_DS)) > + pmu->global_status_rsvd &= ~GLOBAL_STATUS_BUFFER_OVF; > + pmu->global_status_rsvd &= ~GLOBAL_STATUS_COND_CHG; > + > if (vmx_pt_mode_is_host_guest()) > pmu->global_status_rsvd &= ~GLOBAL_STATUS_TRACE_TOPAPMI; >