[PATCH v2 26/54] KVM: x86/pmu: Avoid legacy vPMU code when accessing global_ctrl in passthrough vPMU

Mingwei Zhang
2024-05-06T05:31:17Z

Avoid calling into legacy/emulated vPMU logic such as reprogram_counters()
when passthrough vPMU is enabled. Note that even when passthrough vPMU is
enabled, global_ctrl may still be intercepted if guest VM only sees a
subset of the counters.

Suggested-by: Xiong Zhang <xiong.y.zhang@linux.intel.com>
Signed-off-by: Mingwei Zhang <mizhang@google.com>
---
arch/x86/kvm/pmu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index bd94f2d67f5c..e9047051489e 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -713,7 +713,8 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (pmu->global_ctrl != data) {
diff = pmu->global_ctrl ^ data;
pmu->global_ctrl = data;
- reprogram_counters(pmu, diff);
+ if (!is_passthrough_pmu_enabled(vcpu))
+ reprogram_counters(pmu, diff);
}
break;
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
--
2.45.0.rc1.225.g2a3ae87e7f-goog