diff mbox series

[RFC,v3,46/58] KVM: x86/pmu: Disconnect counter reprogram logic from passthrough PMU

Message ID 20240801045907.4010984-47-mizhang@google.com (mailing list archive)
State New, archived
Headers show
Series Mediated Passthrough vPMU 3.0 for x86 | expand

Commit Message

Mingwei Zhang Aug. 1, 2024, 4:58 a.m. UTC 
Disconnect counter reprogram logic because passthrough PMU never use host
PMU nor does it use perf API to do anything. Instead, when passthrough PMU
is enabled, touching anywhere around counter reprogram part should be an
error.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
 arch/x86/kvm/pmu.c | 3 +++
 arch/x86/kvm/pmu.h | 8 ++++++++
 2 files changed, 11 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 3604cf467b34..fcd188cc389a 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -478,6 +478,9 @@  static int reprogram_counter(struct kvm_pmc *pmc)
 	bool emulate_overflow;
 	u8 fixed_ctr_ctrl;
 
+	if (WARN_ONCE(pmu->passthrough, "Passthrough PMU never reprogram counter\n"))
+		return 0;
+
 	emulate_overflow = pmc_pause_counter(pmc);
 
 	if (!pmc_event_is_allowed(pmc))
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 7e006cb61296..10553bc1ae1d 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -256,6 +256,10 @@  static inline void kvm_init_pmu_capability(const struct kvm_pmu_ops *pmu_ops)
 
 static inline void kvm_pmu_request_counter_reprogram(struct kvm_pmc *pmc)
 {
+	/* Passthrough PMU never reprogram counters via KVM_REQ_PMU. */
+	if (pmc_to_pmu(pmc)->passthrough)
+		return;
+
 	set_bit(pmc->idx, pmc_to_pmu(pmc)->reprogram_pmi);
 	kvm_make_request(KVM_REQ_PMU, pmc->vcpu);
 }
@@ -264,6 +268,10 @@  static inline void reprogram_counters(struct kvm_pmu *pmu, u64 diff)
 {
 	int bit;
 
+	/* Passthrough PMU never reprogram counters via KVM_REQ_PMU. */
+	if (pmu->passthrough)
+		return;
+
 	if (!diff)
 		return;