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Subject[RFC] [PATCH v2 5/5] KVM/x86/vPMU: not do reprogram_counter for Intel hw-assigned vPMC
Date
Considering the cross-mapping issue, this patch directly passes
the intel_pmu_set_msr request value to the hw-assigned vPMC.

This patch would reprogram a counter from host perf scheduler
just one time when it's first requested and keep to reuse it
during a certain period of time until it's lazy-released, which
is associated with HW_LIFE_COUNT_MAX and scheduling time slice.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
arch/x86/kvm/pmu.c | 19 +++++++++++++++
arch/x86/kvm/vmx/pmu_intel.c | 58 +++++++++++++++++++++++++++++++++++---------
2 files changed, 65 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 672e268..d7e7fb6 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -137,6 +137,11 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
}

pmc->perf_event = event;
+ if (pmc_is_assigned(pmc)) {
+ pmc->hw_life_count = HW_LIFE_COUNT_MAX;
+ wrmsrl(pmc->perf_event->hw.event_base, pmc->counter);
+ }
+
clear_bit(pmc->idx, (unsigned long*)&pmc_to_pmu(pmc)->reprogram_pmi);
}

@@ -155,6 +160,13 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
if (!(eventsel & ARCH_PERFMON_EVENTSEL_ENABLE) || !pmc_is_enabled(pmc))
return;

+ if (pmc_is_assigned(pmc)) {
+ pmc->hw_life_count = HW_LIFE_COUNT_MAX;
+ clear_bit(pmc->idx,
+ (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);
+ return;
+ }
+
event_select = eventsel & ARCH_PERFMON_EVENTSEL_EVENT;
unit_mask = (eventsel & ARCH_PERFMON_EVENTSEL_UMASK) >> 8;

@@ -192,6 +204,13 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
if (!en_field || !pmc_is_enabled(pmc))
return;

+ if (pmc_is_assigned(pmc)) {
+ pmc->hw_life_count = HW_LIFE_COUNT_MAX;
+ clear_bit(pmc->idx,
+ (unsigned long *)&pmc_to_pmu(pmc)->reprogram_pmi);
+ return;
+ }
+
pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,
kvm_x86_ops->pmu_ops->find_fixed_event(idx),
!(en_field & 0x2), /* exclude user */
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 63e00ea..2dfdf54 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -163,12 +163,13 @@ static void intel_pmu_disable_host_counter(struct kvm_pmc *pmc)

static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data)
{
+ struct hw_perf_event *hwc;
+ struct kvm_pmc *pmc;
int i;

for (i = 0; i < pmu->nr_arch_fixed_counters; i++) {
u8 new_ctrl = fixed_ctrl_field(data, i);
u8 old_ctrl = fixed_ctrl_field(pmu->fixed_ctr_ctrl, i);
- struct kvm_pmc *pmc;

pmc = get_fixed_pmc(pmu, MSR_CORE_PERF_FIXED_CTR0 + i);

@@ -176,6 +177,19 @@ static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data)
continue;

reprogram_fixed_counter(pmc, new_ctrl, i);
+
+ if (!intel_pmc_is_assigned(pmc))
+ continue;
+
+ hwc = &pmc->perf_event->hw;
+ if (hwc->idx < INTEL_PMC_IDX_FIXED) {
+ u64 config = (new_ctrl == 0) ? 0 :
+ (hwc->config | ARCH_PERFMON_EVENTSEL_ENABLE);
+ wrmsrl(hwc->config_base, config);
+ } else {
+ intel_pmu_update_host_fixed_ctrl(new_ctrl,
+ hwc->idx - INTEL_PMC_IDX_FIXED);
+ }
}

pmu->fixed_ctr_ctrl = data;
@@ -345,6 +359,7 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
struct kvm_pmc *pmc;
+ struct hw_perf_event *hwc;

switch (msr) {
case MSR_CORE_PERF_FIXED_CTR_CTRL:
@@ -362,7 +377,13 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *data)
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_fixed_pmc(pmu, msr))) {
- *data = pmc_read_counter(pmc);
+ if (intel_pmc_is_assigned(pmc)) {
+ hwc = &pmc->perf_event->hw;
+ rdmsrl_safe(hwc->event_base, data);
+ pmc->counter = *data;
+ } else {
+ *data = pmc->counter;
+ }
return 0;
} else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {
*data = pmc->eventsel;
@@ -377,6 +398,7 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
struct kvm_pmc *pmc;
+ struct hw_perf_event *hwc;
u32 msr = msr_info->index;
u64 data = msr_info->data;

@@ -414,18 +436,30 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_fixed_pmc(pmu, msr))) {
- if (!msr_info->host_initiated)
- data = (s64)(s32)data;
- pmc->counter += data - pmc_read_counter(pmc);
- return 0;
- } else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {
- if (data == pmc->eventsel)
- return 0;
- if (!(data & pmu->reserved_bits)) {
- reprogram_gp_counter(pmc, data);
- return 0;
+ pmc->counter = data;
+ if (intel_pmc_is_assigned(pmc)) {
+ hwc = &pmc->perf_event->hw;
+ wrmsrl(hwc->event_base, pmc->counter);
}
+ return 0;
}
+
+ pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0);
+ if (!pmc)
+ return 1;
+
+ if (data == pmc->eventsel
+ || (data & pmu->reserved_bits))
+ return 0;
+
+ reprogram_gp_counter(pmc, data);
+
+ if (pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE)
+ intel_pmu_enable_host_counter(pmc);
+ else
+ intel_pmu_disable_host_counter(pmc);
+
+ return 0;
}

return 1;
--
1.8.3.1
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