[PATCH 14/15] KVM: x86/pmu: Advertise PerfMon version 5 on Intel hosts

[Zide Chen]

From: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>

KVM currently caps the guest PerfMon version at 2 for all Intel
platforms. Now that KVM emulates the basic architectural PMU features
introduced in PerfMon versions 3 through 5, raise the guest PerfMon
version to 5.  Features that require additional emulation support, e.g.
architectural LBR will be enabled separately.

When enable_mediated_pmu is disabled or in the non-Intel paths, KVM
retains the existing cap of version 2.

Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
---
 arch/x86/kvm/pmu.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 7d58f7a2a2db..83332e8ed1e0 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -176,7 +176,18 @@ void kvm_init_pmu_capability(struct kvm_pmu_ops *pmu_ops)
 	}
 
 	memcpy(&kvm_pmu_cap, &kvm_host_pmu, sizeof(kvm_host_pmu));
-	kvm_pmu_cap.version = min(kvm_pmu_cap.version, 2);
+
+	/*
+	 * AnyThread counting is not supported by KVM due to cross-VM
+	 * information leakage concerns on SMT cores. Therefore, AnyThread
+	 * remains unavailable for PerfMon v3/v4 guests, where AnyThread
+	 * deprecation is not enumerated.
+	 */
+	if (is_intel && enable_mediated_pmu)
+		kvm_pmu_cap.version = min(kvm_pmu_cap.version, 5);
+	else
+		kvm_pmu_cap.version = min(kvm_pmu_cap.version, 2);
+
 	kvm_pmu_cap.cntr_mask64 &=
 		GENMASK_ULL(pmu_ops->MAX_NR_GP_COUNTERS - 1, 0);
 	kvm_pmu_cap.fixed_cntr_mask64 &=
-- 
2.54.0