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From:   Like Xu <like.xu@linux.intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, ak@linux.intel.com,
        wei.w.wang@intel.com, kan.liang@intel.com,
        alex.shi@linux.alibaba.com, kvm@vger.kernel.org, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v14 10/11] KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES
Date:   Mon,  1 Feb 2021 14:01:51 +0800
Message-Id: <20210201060152.370069-4-like.xu@linux.intel.com>
In-Reply-To: <20210201060152.370069-1-like.xu@linux.intel.com>
References: <20210201051039.255478-1-like.xu@linux.intel.com>
 <20210201060152.370069-1-like.xu@linux.intel.com>
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Userspace could enable guest LBR feature when the exactly supported
LBR format value is initialized to the MSR_IA32_PERF_CAPABILITIES
and the LBR is also compatible with vPMU version and host cpu model.

The LBR could be enabled on the guest if host perf supports LBR
(checked via x86_perf_get_lbr()) and the vcpu model is compatible
with the host one.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
 arch/x86/kvm/vmx/capabilities.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index 57b940c613ab..c49f3ee8eca8 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -374,11 +374,18 @@ static inline bool vmx_pt_mode_is_host_guest(void)
 
 static inline u64 vmx_get_perf_capabilities(void)
 {
+	u64 perf_cap;
+
+	if (boot_cpu_has(X86_FEATURE_PDCM))
+		rdmsrl(MSR_IA32_PERF_CAPABILITIES, perf_cap);
+
+	perf_cap &= PMU_CAP_LBR_FMT;
+
 	/*
 	 * Since counters are virtualized, KVM would support full
 	 * width counting unconditionally, even if the host lacks it.
 	 */
-	return PMU_CAP_FW_WRITES;
+	return PMU_CAP_FW_WRITES | perf_cap;
 }
 
 static inline u64 vmx_supported_debugctl(void)
-- 
2.29.2