From: Mingwei Zhang <mizhang@xxxxxxxxxx>
Separate passthrough PMU logic from non-passthrough vPMU code. There are
two places in passthrough vPMU when set/get_msr() may call into the
existing non-passthrough vPMU code: 1) set/get counters; 2) set global_ctrl
MSR.
In the former case, non-passthrough vPMU will call into
pmc_{read,write}_counter() which wires to the perf API. Update these
functions to avoid the perf API invocation.
The 2nd case is where global_ctrl MSR writes invokes reprogram_counters()
which will invokes the non-passthrough PMU logic. So use pmu->passthrough
flag to wrap out the call.
Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
---
arch/x86/kvm/pmu.c | 4 +++-
arch/x86/kvm/pmu.h | 10 +++++++++-
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 9e62e96fe48a..de653a67ba93 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -652,7 +652,9 @@ 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);
+ /* Passthrough vPMU never reprogram counters. */
+ if (!pmu->passthrough)
+ reprogram_counters(pmu, diff);
}
break;
case MSR_CORE_PERF_GLOBAL_OVF_CTRL:
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 0fc37a06fe48..ab8d4a8e58a8 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -70,6 +70,9 @@ static inline u64 pmc_read_counter(struct kvm_pmc *pmc)
u64 counter, enabled, running;
counter = pmc->counter;
+ if (pmc_to_pmu(pmc)->passthrough)
+ return counter & pmc_bitmask(pmc);
+
if (pmc->perf_event && !pmc->is_paused)
counter += perf_event_read_value(pmc->perf_event,
&enabled, &running);
@@ -79,7 +82,12 @@ static inline u64 pmc_read_counter(struct kvm_pmc *pmc)
static inline void pmc_write_counter(struct kvm_pmc *pmc, u64 val)
{
- pmc->counter += val - pmc_read_counter(pmc);
+ /* In passthrough PMU, counter value is the actual value in HW. */
+ if (pmc_to_pmu(pmc)->passthrough)
+ pmc->counter = val;
+ else
+ pmc->counter += val - pmc_read_counter(pmc);
+
pmc->counter &= pmc_bitmask(pmc);
}
--
2.34.1
