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Date: Thu, 4 Nov 2021 16:14:13 +0800
From: Like Xu <like.xu.linux@...il.com>
To: Yao Yuan <yaoyuan0329os@...il.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] KVM: x86: Use static calls to reduce kvm_pmu_ops
overhead
On 3/11/2021 8:08 pm, Yao Yuan wrote:
> On Wed, Nov 03, 2021 at 03:03:10PM +0800, Like Xu wrote:
>> Convert kvm_pmu_ops to use static calls.
>>
>> Here are the worst sched_clock() nanosecond numbers for the kvm_pmu_ops
>> functions that is most often called (up to 7 digits of calls) when running
>> a single perf test case in a guest on an ICX 2.70GHz host (mitigations=on):
>>
>> | legacy | static call
>> ------------------------------------------------------------
>> .pmc_idx_to_pmc | 10946 | 10047 (8%)
>> .pmc_is_enabled | 11291 | 11175 (1%)
>> .msr_idx_to_pmc | 13526 | 12346 (8%)
>> .is_valid_msr | 10895 | 10484 (3%)
>>
>> Signed-off-by: Like Xu <likexu@...cent.com>
>> ---
>> arch/x86/kvm/pmu.c | 36 +++++++++++++++++-------------------
>> arch/x86/kvm/pmu.h | 2 +-
>> arch/x86/kvm/vmx/nested.c | 2 +-
>> arch/x86/kvm/x86.c | 4 +++-
>> 4 files changed, 22 insertions(+), 22 deletions(-)
>>
>> diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
>> index b6f08c719125..193f925e2064 100644
>> --- a/arch/x86/kvm/pmu.c
>> +++ b/arch/x86/kvm/pmu.c
>> @@ -224,7 +224,7 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
>> ARCH_PERFMON_EVENTSEL_CMASK |
>> HSW_IN_TX |
>> HSW_IN_TX_CHECKPOINTED))) {
>> - config = kvm_pmu_ops.find_arch_event(pmc_to_pmu(pmc),
>> + config = static_call(kvm_x86_pmu_find_arch_event)(pmc_to_pmu(pmc),
>
> Why you need change them into kvm_pmu_ops.XXX then convert
> them into static call ? Move the instance definition of
> kvm_pmu_ops from patch 1 into patch 3 and then drop patch 1,
> will this work ?
You may git squash all commits to get it *work*.
With reference to afaf0b2f9b801c6eb2278b52d49e6a7d7b659cf1[1],
doing one thing at a time will make things go smoother.
[1]
https://lore.kernel.org/lkml/20200321202603.19355-7-sean.j.christopherson@intel.com/
>
>> event_select,
>> unit_mask);
>> if (config != PERF_COUNT_HW_MAX)
>> @@ -278,7 +278,7 @@ void reprogram_fixed_counter(struct kvm_pmc *pmc, u8 ctrl, int idx)
>>
>> pmc->current_config = (u64)ctrl;
>> pmc_reprogram_counter(pmc, PERF_TYPE_HARDWARE,
>> - kvm_pmu_ops.find_fixed_event(idx),
>> + static_call(kvm_x86_pmu_find_fixed_event)(idx),
>> !(en_field & 0x2), /* exclude user */
>> !(en_field & 0x1), /* exclude kernel */
>> pmi, false, false);
>> @@ -287,7 +287,7 @@ EXPORT_SYMBOL_GPL(reprogram_fixed_counter);
>>
>> void reprogram_counter(struct kvm_pmu *pmu, int pmc_idx)
>> {
>> - struct kvm_pmc *pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, pmc_idx);
>> + struct kvm_pmc *pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, pmc_idx);
>>
>> if (!pmc)
>> return;
>> @@ -309,7 +309,7 @@ void kvm_pmu_handle_event(struct kvm_vcpu *vcpu)
>> int bit;
>>
>> for_each_set_bit(bit, pmu->reprogram_pmi, X86_PMC_IDX_MAX) {
>> - struct kvm_pmc *pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, bit);
>> + struct kvm_pmc *pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, bit);
>>
>> if (unlikely(!pmc || !pmc->perf_event)) {
>> clear_bit(bit, pmu->reprogram_pmi);
>> @@ -331,7 +331,7 @@ void kvm_pmu_handle_event(struct kvm_vcpu *vcpu)
>> /* check if idx is a valid index to access PMU */
>> int kvm_pmu_is_valid_rdpmc_ecx(struct kvm_vcpu *vcpu, unsigned int idx)
>> {
>> - return kvm_pmu_ops.is_valid_rdpmc_ecx(vcpu, idx);
>> + return static_call(kvm_x86_pmu_is_valid_rdpmc_ecx)(vcpu, idx);
>> }
>>
>> bool is_vmware_backdoor_pmc(u32 pmc_idx)
>> @@ -381,7 +381,7 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
>> if (is_vmware_backdoor_pmc(idx))
>> return kvm_pmu_rdpmc_vmware(vcpu, idx, data);
>>
>> - pmc = kvm_pmu_ops.rdpmc_ecx_to_pmc(vcpu, idx, &mask);
>> + pmc = static_call(kvm_x86_pmu_rdpmc_ecx_to_pmc)(vcpu, idx, &mask);
>> if (!pmc)
>> return 1;
>>
>> @@ -397,22 +397,21 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
>> void kvm_pmu_deliver_pmi(struct kvm_vcpu *vcpu)
>> {
>> if (lapic_in_kernel(vcpu)) {
>> - if (kvm_pmu_ops.deliver_pmi)
>> - kvm_pmu_ops.deliver_pmi(vcpu);
>> + static_call_cond(kvm_x86_pmu_deliver_pmi)(vcpu);
>> kvm_apic_local_deliver(vcpu->arch.apic, APIC_LVTPC);
>> }
>> }
>>
>> bool kvm_pmu_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
>> {
>> - return kvm_pmu_ops.msr_idx_to_pmc(vcpu, msr) ||
>> - kvm_pmu_ops.is_valid_msr(vcpu, msr);
>> + return static_call(kvm_x86_pmu_msr_idx_to_pmc)(vcpu, msr) ||
>> + static_call(kvm_x86_pmu_is_valid_msr)(vcpu, msr);
>> }
>>
>> static void kvm_pmu_mark_pmc_in_use(struct kvm_vcpu *vcpu, u32 msr)
>> {
>> struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
>> - struct kvm_pmc *pmc = kvm_pmu_ops.msr_idx_to_pmc(vcpu, msr);
>> + struct kvm_pmc *pmc = static_call(kvm_x86_pmu_msr_idx_to_pmc)(vcpu, msr);
>>
>> if (pmc)
>> __set_bit(pmc->idx, pmu->pmc_in_use);
>> @@ -420,13 +419,13 @@ static void kvm_pmu_mark_pmc_in_use(struct kvm_vcpu *vcpu, u32 msr)
>>
>> int kvm_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>> {
>> - return kvm_pmu_ops.get_msr(vcpu, msr_info);
>> + return static_call(kvm_x86_pmu_get_msr)(vcpu, msr_info);
>> }
>>
>> int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>> {
>> kvm_pmu_mark_pmc_in_use(vcpu, msr_info->index);
>> - return kvm_pmu_ops.set_msr(vcpu, msr_info);
>> + return static_call(kvm_x86_pmu_set_msr)(vcpu, msr_info);
>> }
>>
>> /* refresh PMU settings. This function generally is called when underlying
>> @@ -435,7 +434,7 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>> */
>> void kvm_pmu_refresh(struct kvm_vcpu *vcpu)
>> {
>> - kvm_pmu_ops.refresh(vcpu);
>> + static_call(kvm_x86_pmu_refresh)(vcpu);
>> }
>>
>> void kvm_pmu_reset(struct kvm_vcpu *vcpu)
>> @@ -443,7 +442,7 @@ void kvm_pmu_reset(struct kvm_vcpu *vcpu)
>> struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
>>
>> irq_work_sync(&pmu->irq_work);
>> - kvm_pmu_ops.reset(vcpu);
>> + static_call(kvm_x86_pmu_reset)(vcpu);
>> }
>>
>> void kvm_pmu_init(struct kvm_vcpu *vcpu)
>> @@ -451,7 +450,7 @@ void kvm_pmu_init(struct kvm_vcpu *vcpu)
>> struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
>>
>> memset(pmu, 0, sizeof(*pmu));
>> - kvm_pmu_ops.init(vcpu);
>> + static_call(kvm_x86_pmu_init)(vcpu);
>> init_irq_work(&pmu->irq_work, kvm_pmi_trigger_fn);
>> pmu->event_count = 0;
>> pmu->need_cleanup = false;
>> @@ -483,14 +482,13 @@ void kvm_pmu_cleanup(struct kvm_vcpu *vcpu)
>> pmu->pmc_in_use, X86_PMC_IDX_MAX);
>>
>> for_each_set_bit(i, bitmask, X86_PMC_IDX_MAX) {
>> - pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, i);
>> + pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i);
>>
>> if (pmc && pmc->perf_event && !pmc_speculative_in_use(pmc))
>> pmc_stop_counter(pmc);
>> }
>>
>> - if (kvm_pmu_ops.cleanup)
>> - kvm_pmu_ops.cleanup(vcpu);
>> + static_call_cond(kvm_x86_pmu_cleanup)(vcpu);
>>
>> bitmap_zero(pmu->pmc_in_use, X86_PMC_IDX_MAX);
>> }
>> diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
>> index e5550d4acf14..1818d1371ece 100644
>> --- a/arch/x86/kvm/pmu.h
>> +++ b/arch/x86/kvm/pmu.h
>> @@ -109,7 +109,7 @@ static inline bool pmc_is_fixed(struct kvm_pmc *pmc)
>>
>> static inline bool pmc_is_enabled(struct kvm_pmc *pmc)
>> {
>> - return kvm_pmu_ops.pmc_is_enabled(pmc);
>> + return static_call(kvm_x86_pmu_pmc_is_enabled)(pmc);
>> }
>>
>> static inline bool kvm_valid_perf_global_ctrl(struct kvm_pmu *pmu,
>> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> index 1e793e44b5ff..a61661de1f39 100644
>> --- a/arch/x86/kvm/vmx/nested.c
>> +++ b/arch/x86/kvm/vmx/nested.c
>> @@ -4796,7 +4796,7 @@ void nested_vmx_pmu_entry_exit_ctls_update(struct kvm_vcpu *vcpu)
>> return;
>>
>> vmx = to_vmx(vcpu);
>> - if (kvm_pmu_ops.is_valid_msr(vcpu, MSR_CORE_PERF_GLOBAL_CTRL)) {
>> + if (static_call(kvm_x86_pmu_is_valid_msr)(vcpu, MSR_CORE_PERF_GLOBAL_CTRL)) {
>> vmx->nested.msrs.entry_ctls_high |=
>> VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL;
>> vmx->nested.msrs.exit_ctls_high |=
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 72d286595012..88a3ef809c98 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -11317,8 +11317,10 @@ int kvm_arch_hardware_setup(void *opaque)
>> memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
>> kvm_ops_static_call_update();
>>
>> - if (kvm_x86_ops.hardware_enable)
>> + if (kvm_x86_ops.hardware_enable) {
>> memcpy(&kvm_pmu_ops, kvm_x86_ops.pmu_ops, sizeof(kvm_pmu_ops));
>> + kvm_pmu_ops_static_call_update();
>> + }
>>
>> if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
>> supported_xss = 0;
>> --
>> 2.33.0
>>
>
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