Re: [PATCH 3/3] KVM: x86: Use static calls to reduce kvm_pmu_ops overhead
From: Like Xu
Date: Thu Nov 04 2021 - 04:14:27 EST
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@xxxxxxxxxxx>
---
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@xxxxxxxxx/
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