[RFC,v3,50/58] KVM: x86/pmu/svm: Set enable_passthrough_pmu module parameter

Commit Message

Mingwei Zhang Aug. 1, 2024, 4:58 a.m. UTC

From: Sandipan Das <[e-mail]>

Since passthrough PMU can be also used on some AMD platforms, set the
"enable_passthrough_pmu" KVM kernel module parameter to true when the
following conditions are met.
 - parameter is set to true when module loaded
 - enable_pmu is true
 - is running on and AMD CPU
 - CPU supports PerfMonV2
 - host PMU supports passthrough mode

Signed-off-by: Sandipan Das <[e-mail]>
Signed-off-by: Mingwei Zhang <[e-mail]>
---
 arch/x86/kvm/pmu.h     | 22 ++++++++++++++--------
 arch/x86/kvm/svm/svm.c |  2 ++
 2 files changed, 16 insertions(+), 8 deletions(-)

Patch

diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 10553bc1ae1d..9fb3ddfd3a10 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -196,6 +196,7 @@  extern struct kvm_pmu_emulated_event_selectors kvm_pmu_eventsel;
 static inline void kvm_init_pmu_capability(const struct kvm_pmu_ops *pmu_ops)
 {
 	bool is_intel = boot_cpu_data.x86_vendor == X86_VENDOR_INTEL;
+	bool is_amd = boot_cpu_data.x86_vendor == X86_VENDOR_AMD;
 	int min_nr_gp_ctrs = pmu_ops->MIN_NR_GP_COUNTERS;
 
 	/*
@@ -223,18 +224,23 @@  static inline void kvm_init_pmu_capability(const struct kvm_pmu_ops *pmu_ops)
 			enable_pmu = false;
 	}
 
-	/* Pass-through vPMU is only supported in Intel CPUs. */
-	if (!is_intel)
+	/* Pass-through vPMU is only supported in Intel and AMD CPUs. */
+	if (!is_intel && !is_amd)
 		enable_passthrough_pmu = false;
 
 	/*
-	 * Pass-through vPMU requires at least PerfMon version 4 because the
-	 * implementation requires the usage of MSR_CORE_PERF_GLOBAL_STATUS_SET
-	 * for counter emulation as well as PMU context switch.  In addition, it
-	 * requires host PMU support on passthrough mode. Disable pass-through
-	 * vPMU if any condition fails.
+	 * On Intel platforms, pass-through vPMU requires at least PerfMon
+	 * version 4 because the implementation requires the usage of
+	 * MSR_CORE_PERF_GLOBAL_STATUS_SET for counter emulation as well as
+	 * PMU context switch.  In addition, it requires host PMU support on
+	 * passthrough mode. Disable pass-through vPMU if any condition fails.
+	 *
+	 * On AMD platforms, pass-through vPMU requires at least PerfMonV2
+	 * because MSR_PERF_CNTR_GLOBAL_STATUS_SET is required.
 	 */
-	if (!enable_pmu || kvm_pmu_cap.version < 4 || !kvm_pmu_cap.passthrough)
+	if (!enable_pmu || !kvm_pmu_cap.passthrough ||
+	    (is_intel && kvm_pmu_cap.version < 4) ||
+	    (is_amd && kvm_pmu_cap.version < 2))
 		enable_passthrough_pmu = false;
 
 	if (!enable_pmu) {
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 296c524988f9..12868b7e6f51 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -239,6 +239,8 @@  module_param(intercept_smi, bool, 0444);
 bool vnmi = true;
 module_param(vnmi, bool, 0444);
 
+module_param(enable_passthrough_pmu, bool, 0444);
+
 static bool svm_gp_erratum_intercept = true;
 
 static u8 rsm_ins_bytes[] = "\x0f\xaa";