linux-kernel - [PATCH v3 5/5] KVM: x86/pmu: Expose PEBS-via-PT in the KVM supported capabilities

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Date:   Wed, 12 May 2021 16:44:46 +0800
From:   Like Xu <like.xu@...ux.intel.com>
To:     Paolo Bonzini <pbonzini@...hat.com>, peterz@...radead.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, weijiang.yang@...el.com,
        eranian@...gle.com, wei.w.wang@...el.com, kvm@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Like Xu <like.xu@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andi Kleen <andi.kleen@...el.com>
Subject: [PATCH v3 5/5] KVM: x86/pmu: Expose PEBS-via-PT in the KVM supported capabilities

The hypervisor userspace can dis/enable it via the MSR-based feature
"MSR_IA32_PERF_CAPABILITIES [bit 16]". If guest also has basic PT support,
it can output the PEBS records to the PT buffer.

Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Andi Kleen <andi.kleen@...el.com>
Signed-off-by: Like Xu <like.xu@...ux.intel.com>
---
 arch/x86/kvm/vmx/capabilities.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index fd8c9822db9e..e04b50174dd5 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -398,8 +398,11 @@ static inline u64 vmx_get_perf_capabilities(void)
 
 	perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
 
-	if (vmx_pebs_supported())
+	if (vmx_pebs_supported()) {
 		perf_cap |= host_perf_cap & PERF_CAP_PEBS_MASK;
+		if (vmx_pt_mode_is_host_guest())
+			perf_cap |= host_perf_cap & PERF_CAP_PEBS_OUTPUT_PT;
+	}
 
 	return perf_cap;
 }
-- 
2.31.1