[PATCH v3.1 0/4] KVM: x86: Use static calls to reduce kvm_pmu_ops overhead

[PATCH v3.1 0/4] KVM: x86: Use static calls to reduce kvm_pmu_ops overhead

[Sean Christopherson]

This is a minor iteration on Like's v3 to allow kvm_pmu_ops (the global
variable, not the struct) be static.  I ran the PMU unit tests and compiled,
but otherwise it's untested.  Strongly recommend waiting for Like to give
a thumbs up before applying :-)

[*] https://lore.kernel.org/all/20220307115920.51099-1-likexu@tencent.com

Like Xu (4):
  KVM: x86: Move kvm_ops_static_call_update() to x86.c
  KVM: x86: Copy kvm_pmu_ops by value to eliminate layer of indirection
  KVM: x86: Move .pmu_ops to kvm_x86_init_ops and tag as __initdata
  KVM: x86: Use static calls to reduce kvm_pmu_ops overhead

 arch/x86/include/asm/kvm-x86-pmu-ops.h | 31 ++++++++++++
 arch/x86/include/asm/kvm_host.h        | 17 +------
 arch/x86/kvm/pmu.c                     | 66 ++++++++++++++++++--------
 arch/x86/kvm/pmu.h                     |  7 +--
 arch/x86/kvm/svm/pmu.c                 |  2 +-
 arch/x86/kvm/svm/svm.c                 |  2 +-
 arch/x86/kvm/vmx/pmu_intel.c           |  2 +-
 arch/x86/kvm/vmx/vmx.c                 |  2 +-
 arch/x86/kvm/x86.c                     | 21 +++++++-
 9 files changed, 102 insertions(+), 48 deletions(-)
 create mode 100644 arch/x86/include/asm/kvm-x86-pmu-ops.h


base-commit: 19164ad08bf668bca4f4bfbaacaa0a47c1b737a6
-- 
2.35.1.1021.g381101b075-goog

[PATCH v3.1 1/4] KVM: x86: Move kvm_ops_static_call_update() to x86.c

[Sean Christopherson]

From: Like Xu <likexu@tencent.com>

The kvm_ops_static_call_update() is defined in kvm_host.h. That's
completely unnecessary, it should have exactly one caller,
kvm_arch_hardware_setup().  Move the helper to x86.c and have it do the
actual memcpy() of the ops in addition to the static call updates.  This
will also allow for cleanly giving kvm_pmu_ops static_call treatment.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
[sean: Move memcpy() into the helper and rename accordingly]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h | 14 --------------
 arch/x86/kvm/x86.c              | 19 +++++++++++++++++--
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9694dd5e6ccc..df4e057b0417 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1557,20 +1557,6 @@ extern struct kvm_x86_ops kvm_x86_ops;
 #define KVM_X86_OP_OPTIONAL_RET0 KVM_X86_OP
 #include <asm/kvm-x86-ops.h>
 
-static inline void kvm_ops_static_call_update(void)
-{
-#define __KVM_X86_OP(func) \
-	static_call_update(kvm_x86_##func, kvm_x86_ops.func);
-#define KVM_X86_OP(func) \
-	WARN_ON(!kvm_x86_ops.func); __KVM_X86_OP(func)
-#define KVM_X86_OP_OPTIONAL __KVM_X86_OP
-#define KVM_X86_OP_OPTIONAL_RET0(func) \
-	static_call_update(kvm_x86_##func, (void *)kvm_x86_ops.func ? : \
-					   (void *)__static_call_return0);
-#include <asm/kvm-x86-ops.h>
-#undef __KVM_X86_OP
-}
-
 #define __KVM_HAVE_ARCH_VM_ALLOC
 static inline struct kvm *kvm_arch_alloc_vm(void)
 {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d3a9ce07a565..99aa2d16845a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11595,6 +11595,22 @@ void kvm_arch_hardware_disable(void)
 	drop_user_return_notifiers();
 }
 
+static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
+{
+	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
+
+#define __KVM_X86_OP(func) \
+	static_call_update(kvm_x86_##func, kvm_x86_ops.func);
+#define KVM_X86_OP(func) \
+	WARN_ON(!kvm_x86_ops.func); __KVM_X86_OP(func)
+#define KVM_X86_OP_OPTIONAL __KVM_X86_OP
+#define KVM_X86_OP_OPTIONAL_RET0(func) \
+	static_call_update(kvm_x86_##func, (void *)kvm_x86_ops.func ? : \
+					   (void *)__static_call_return0);
+#include <asm/kvm-x86-ops.h>
+#undef __KVM_X86_OP
+}
+
 int kvm_arch_hardware_setup(void *opaque)
 {
 	struct kvm_x86_init_ops *ops = opaque;
@@ -11609,8 +11625,7 @@ int kvm_arch_hardware_setup(void *opaque)
 	if (r != 0)
 		return r;
 
-	memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
-	kvm_ops_static_call_update();
+	kvm_ops_update(ops);
 
 	kvm_register_perf_callbacks(ops->handle_intel_pt_intr);
 
-- 
2.35.1.1021.g381101b075-goog

[PATCH v3.1 2/4] KVM: x86: Copy kvm_pmu_ops by value to eliminate layer of indirection

[Sean Christopherson]

From: Like Xu <likexu@tencent.com>

Replace the kvm_pmu_ops pointer in common x86 with an instance of the
struct to save one pointer dereference when invoking functions. Copy the
struct by value to set the ops during kvm_init().

Signed-off-by: Like Xu <likexu@tencent.com>
[sean: Move pmc_is_enabled(), make kvm_pmu_ops static]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/pmu.c | 54 ++++++++++++++++++++++++++++------------------
 arch/x86/kvm/pmu.h |  7 ++----
 arch/x86/kvm/x86.c |  2 ++
 3 files changed, 37 insertions(+), 26 deletions(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index eca39f56c231..bb0b1ad0fda5 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -49,6 +49,18 @@
  *        * AMD:   [0 .. AMD64_NUM_COUNTERS-1] <=> gp counters
  */
 
+static struct kvm_pmu_ops kvm_pmu_ops __read_mostly;
+
+void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops)
+{
+	memcpy(&kvm_pmu_ops, pmu_ops, sizeof(kvm_pmu_ops));
+}
+
+static inline bool pmc_is_enabled(struct kvm_pmc *pmc)
+{
+	return kvm_pmu_ops.pmc_is_enabled(pmc);
+}
+
 static void kvm_pmi_trigger_fn(struct irq_work *irq_work)
 {
 	struct kvm_pmu *pmu = container_of(irq_work, struct kvm_pmu, irq_work);
@@ -213,7 +225,7 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
 			  ARCH_PERFMON_EVENTSEL_CMASK |
 			  HSW_IN_TX |
 			  HSW_IN_TX_CHECKPOINTED))) {
-		config = kvm_x86_ops.pmu_ops->pmc_perf_hw_id(pmc);
+		config = kvm_pmu_ops.pmc_perf_hw_id(pmc);
 		if (config != PERF_COUNT_HW_MAX)
 			type = PERF_TYPE_HARDWARE;
 	}
@@ -263,7 +275,7 @@ 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_x86_ops.pmu_ops->pmc_perf_hw_id(pmc),
+			      kvm_pmu_ops.pmc_perf_hw_id(pmc),
 			      !(en_field & 0x2), /* exclude user */
 			      !(en_field & 0x1), /* exclude kernel */
 			      pmi);
@@ -272,7 +284,7 @@ EXPORT_SYMBOL_GPL(reprogram_fixed_counter);
 
 void reprogram_counter(struct kvm_pmu *pmu, int pmc_idx)
 {
-	struct kvm_pmc *pmc = kvm_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, pmc_idx);
+	struct kvm_pmc *pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, pmc_idx);
 
 	if (!pmc)
 		return;
@@ -294,7 +306,7 @@ 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_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, bit);
+		struct kvm_pmc *pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, bit);
 
 		if (unlikely(!pmc || !pmc->perf_event)) {
 			clear_bit(bit, pmu->reprogram_pmi);
@@ -316,7 +328,7 @@ void kvm_pmu_handle_event(struct kvm_vcpu *vcpu)
 /* check if idx is a valid index to access PMU */
 bool kvm_pmu_is_valid_rdpmc_ecx(struct kvm_vcpu *vcpu, unsigned int idx)
 {
-	return kvm_x86_ops.pmu_ops->is_valid_rdpmc_ecx(vcpu, idx);
+	return kvm_pmu_ops.is_valid_rdpmc_ecx(vcpu, idx);
 }
 
 bool is_vmware_backdoor_pmc(u32 pmc_idx)
@@ -366,7 +378,7 @@ 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_x86_ops.pmu_ops->rdpmc_ecx_to_pmc(vcpu, idx, &mask);
+	pmc = kvm_pmu_ops.rdpmc_ecx_to_pmc(vcpu, idx, &mask);
 	if (!pmc)
 		return 1;
 
@@ -382,22 +394,22 @@ 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_x86_ops.pmu_ops->deliver_pmi)
-			kvm_x86_ops.pmu_ops->deliver_pmi(vcpu);
+		if (kvm_pmu_ops.deliver_pmi)
+			kvm_pmu_ops.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_x86_ops.pmu_ops->msr_idx_to_pmc(vcpu, msr) ||
-		kvm_x86_ops.pmu_ops->is_valid_msr(vcpu, msr);
+	return kvm_pmu_ops.msr_idx_to_pmc(vcpu, msr) ||
+		kvm_pmu_ops.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_x86_ops.pmu_ops->msr_idx_to_pmc(vcpu, msr);
+	struct kvm_pmc *pmc = kvm_pmu_ops.msr_idx_to_pmc(vcpu, msr);
 
 	if (pmc)
 		__set_bit(pmc->idx, pmu->pmc_in_use);
@@ -405,13 +417,13 @@ 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_x86_ops.pmu_ops->get_msr(vcpu, msr_info);
+	return kvm_pmu_ops.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_x86_ops.pmu_ops->set_msr(vcpu, msr_info);
+	return kvm_pmu_ops.set_msr(vcpu, msr_info);
 }
 
 /* refresh PMU settings. This function generally is called when underlying
@@ -420,7 +432,7 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
  */
 void kvm_pmu_refresh(struct kvm_vcpu *vcpu)
 {
-	kvm_x86_ops.pmu_ops->refresh(vcpu);
+	kvm_pmu_ops.refresh(vcpu);
 }
 
 void kvm_pmu_reset(struct kvm_vcpu *vcpu)
@@ -428,7 +440,7 @@ void kvm_pmu_reset(struct kvm_vcpu *vcpu)
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
 
 	irq_work_sync(&pmu->irq_work);
-	kvm_x86_ops.pmu_ops->reset(vcpu);
+	kvm_pmu_ops.reset(vcpu);
 }
 
 void kvm_pmu_init(struct kvm_vcpu *vcpu)
@@ -436,7 +448,7 @@ void kvm_pmu_init(struct kvm_vcpu *vcpu)
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
 
 	memset(pmu, 0, sizeof(*pmu));
-	kvm_x86_ops.pmu_ops->init(vcpu);
+	kvm_pmu_ops.init(vcpu);
 	init_irq_work(&pmu->irq_work, kvm_pmi_trigger_fn);
 	pmu->event_count = 0;
 	pmu->need_cleanup = false;
@@ -468,14 +480,14 @@ 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_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, i);
+		pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, i);
 
 		if (pmc && pmc->perf_event && !pmc_speculative_in_use(pmc))
 			pmc_stop_counter(pmc);
 	}
 
-	if (kvm_x86_ops.pmu_ops->cleanup)
-		kvm_x86_ops.pmu_ops->cleanup(vcpu);
+	if (kvm_pmu_ops.cleanup)
+		kvm_pmu_ops.cleanup(vcpu);
 
 	bitmap_zero(pmu->pmc_in_use, X86_PMC_IDX_MAX);
 }
@@ -505,7 +517,7 @@ static inline bool eventsel_match_perf_hw_id(struct kvm_pmc *pmc,
 	unsigned int config;
 
 	pmc->eventsel &= (ARCH_PERFMON_EVENTSEL_EVENT | ARCH_PERFMON_EVENTSEL_UMASK);
-	config = kvm_x86_ops.pmu_ops->pmc_perf_hw_id(pmc);
+	config = kvm_pmu_ops.pmc_perf_hw_id(pmc);
 	pmc->eventsel = old_eventsel;
 	return config == perf_hw_id;
 }
@@ -533,7 +545,7 @@ void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id)
 	int i;
 
 	for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) {
-		pmc = kvm_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, i);
+		pmc = kvm_pmu_ops.pmc_idx_to_pmc(pmu, i);
 
 		if (!pmc || !pmc_is_enabled(pmc) || !pmc_speculative_in_use(pmc))
 			continue;
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 7a7b8d5b775e..cbe9987f9cba 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -41,6 +41,8 @@ struct kvm_pmu_ops {
 	void (*cleanup)(struct kvm_vcpu *vcpu);
 };
 
+void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops);
+
 static inline u64 pmc_bitmask(struct kvm_pmc *pmc)
 {
 	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
@@ -88,11 +90,6 @@ static inline bool pmc_is_fixed(struct kvm_pmc *pmc)
 	return pmc->type == KVM_PMC_FIXED;
 }
 
-static inline bool pmc_is_enabled(struct kvm_pmc *pmc)
-{
-	return kvm_x86_ops.pmu_ops->pmc_is_enabled(pmc);
-}
-
 static inline bool kvm_valid_perf_global_ctrl(struct kvm_pmu *pmu,
 						 u64 data)
 {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 99aa2d16845a..6f1676fab6c5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11609,6 +11609,8 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
 					   (void *)__static_call_return0);
 #include <asm/kvm-x86-ops.h>
 #undef __KVM_X86_OP
+
+	kvm_pmu_ops_update(ops->runtime_ops->pmu_ops);
 }
 
 int kvm_arch_hardware_setup(void *opaque)
-- 
2.35.1.1021.g381101b075-goog

[PATCH v3.1 3/4] KVM: x86: Move .pmu_ops to kvm_x86_init_ops and tag as __initdata

[Sean Christopherson]

From: Like Xu <likexu@tencent.com>

The pmu_ops should be moved to kvm_x86_init_ops and tagged as __initdata.
That'll save those precious few bytes, and more importantly make
the original ops unreachable, i.e. make it harder to sneak in post-init
modification bugs.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Like Xu <likexu@tencent.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm_host.h | 3 +--
 arch/x86/kvm/svm/pmu.c          | 2 +-
 arch/x86/kvm/svm/svm.c          | 2 +-
 arch/x86/kvm/vmx/pmu_intel.c    | 2 +-
 arch/x86/kvm/vmx/vmx.c          | 2 +-
 arch/x86/kvm/x86.c              | 2 +-
 6 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index df4e057b0417..5bb5843d460a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1464,8 +1464,6 @@ struct kvm_x86_ops {
 	int cpu_dirty_log_size;
 	void (*update_cpu_dirty_logging)(struct kvm_vcpu *vcpu);
 
-	/* pmu operations of sub-arch */
-	const struct kvm_pmu_ops *pmu_ops;
 	const struct kvm_x86_nested_ops *nested_ops;
 
 	void (*vcpu_blocking)(struct kvm_vcpu *vcpu);
@@ -1536,6 +1534,7 @@ struct kvm_x86_init_ops {
 	unsigned int (*handle_intel_pt_intr)(void);
 
 	struct kvm_x86_ops *runtime_ops;
+	struct kvm_pmu_ops *pmu_ops;
 };
 
 struct kvm_arch_async_pf {
diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index 24eb935b6f85..57ab4739eb19 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -319,7 +319,7 @@ static void amd_pmu_reset(struct kvm_vcpu *vcpu)
 	}
 }
 
-struct kvm_pmu_ops amd_pmu_ops = {
+struct kvm_pmu_ops amd_pmu_ops __initdata = {
 	.pmc_perf_hw_id = amd_pmc_perf_hw_id,
 	.pmc_is_enabled = amd_pmc_is_enabled,
 	.pmc_idx_to_pmc = amd_pmc_idx_to_pmc,
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 6535adee3e9c..f3c9aa8624d8 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4625,7 +4625,6 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 
 	.sched_in = svm_sched_in,
 
-	.pmu_ops = &amd_pmu_ops,
 	.nested_ops = &svm_nested_ops,
 
 	.deliver_interrupt = svm_deliver_interrupt,
@@ -4906,6 +4905,7 @@ static struct kvm_x86_init_ops svm_init_ops __initdata = {
 	.check_processor_compatibility = svm_check_processor_compat,
 
 	.runtime_ops = &svm_x86_ops,
+	.pmu_ops = &amd_pmu_ops,
 };
 
 static int __init svm_init(void)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index efa172a7278e..c766c9b3083a 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -723,7 +723,7 @@ static void intel_pmu_cleanup(struct kvm_vcpu *vcpu)
 		intel_pmu_release_guest_lbr_event(vcpu);
 }
 
-struct kvm_pmu_ops intel_pmu_ops = {
+struct kvm_pmu_ops intel_pmu_ops __initdata = {
 	.pmc_perf_hw_id = intel_pmc_perf_hw_id,
 	.pmc_is_enabled = intel_pmc_is_enabled,
 	.pmc_idx_to_pmc = intel_pmc_idx_to_pmc,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 84a7500cd80c..77ba0cfe588f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7823,7 +7823,6 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 	.cpu_dirty_log_size = PML_ENTITY_NUM,
 	.update_cpu_dirty_logging = vmx_update_cpu_dirty_logging,
 
-	.pmu_ops = &intel_pmu_ops,
 	.nested_ops = &vmx_nested_ops,
 
 	.pi_update_irte = vmx_pi_update_irte,
@@ -8078,6 +8077,7 @@ static struct kvm_x86_init_ops vmx_init_ops __initdata = {
 	.handle_intel_pt_intr = NULL,
 
 	.runtime_ops = &vmx_x86_ops,
+	.pmu_ops = &intel_pmu_ops,
 };
 
 static void vmx_cleanup_l1d_flush(void)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6f1676fab6c5..ca48cf705917 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11610,7 +11610,7 @@ static inline void kvm_ops_update(struct kvm_x86_init_ops *ops)
 #include <asm/kvm-x86-ops.h>
 #undef __KVM_X86_OP
 
-	kvm_pmu_ops_update(ops->runtime_ops->pmu_ops);
+	kvm_pmu_ops_update(ops->pmu_ops);
 }
 
 int kvm_arch_hardware_setup(void *opaque)
-- 
2.35.1.1021.g381101b075-goog

[PATCH v3.1 4/4] KVM: x86: Use static calls to reduce kvm_pmu_ops overhead

[Sean Christopherson]

From: Like Xu <likexu@tencent.com>

Use static calls to improve kvm_pmu_ops performance, following the same
pattern and naming scheme used by kvm-x86-ops.h.

Here are the worst fenced_rdtsc() cycles 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	|	1304840	|	994872 (+23%)
.pmc_is_enabled	|	978670	|	1011750 (-3%)
.msr_idx_to_pmc	|	47828	|	41690 (+12%)
.is_valid_msr	|	28786	|	30108 (-4%)

Signed-off-by: Like Xu <likexu@tencent.com>
[sean: Handle static call updates in pmu.c, tweak changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/include/asm/kvm-x86-pmu-ops.h | 31 ++++++++++++++
 arch/x86/kvm/pmu.c                     | 56 ++++++++++++++++----------
 2 files changed, 65 insertions(+), 22 deletions(-)
 create mode 100644 arch/x86/include/asm/kvm-x86-pmu-ops.h

diff --git a/arch/x86/include/asm/kvm-x86-pmu-ops.h b/arch/x86/include/asm/kvm-x86-pmu-ops.h
new file mode 100644
index 000000000000..fdfd8e06fee6
--- /dev/null
+++ b/arch/x86/include/asm/kvm-x86-pmu-ops.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#if !defined(KVM_X86_PMU_OP) || !defined(KVM_X86_PMU_OP_OPTIONAL)
+BUILD_BUG_ON(1)
+#endif
+
+/*
+ * KVM_X86_PMU_OP() and KVM_X86_PMU_OP_OPTIONAL() are used to help generate
+ * both DECLARE/DEFINE_STATIC_CALL() invocations and
+ * "static_call_update()" calls.
+ *
+ * KVM_X86_PMU_OP_OPTIONAL() can be used for those functions that can have
+ * a NULL definition, for example if "static_call_cond()" will be used
+ * at the call sites.
+ */
+KVM_X86_PMU_OP(pmc_perf_hw_id)
+KVM_X86_PMU_OP(pmc_is_enabled)
+KVM_X86_PMU_OP(pmc_idx_to_pmc)
+KVM_X86_PMU_OP(rdpmc_ecx_to_pmc)
+KVM_X86_PMU_OP(msr_idx_to_pmc)
+KVM_X86_PMU_OP(is_valid_rdpmc_ecx)
+KVM_X86_PMU_OP(is_valid_msr)
+KVM_X86_PMU_OP(get_msr)
+KVM_X86_PMU_OP(set_msr)
+KVM_X86_PMU_OP(refresh)
+KVM_X86_PMU_OP(init)
+KVM_X86_PMU_OP(reset)
+KVM_X86_PMU_OP_OPTIONAL(deliver_pmi)
+KVM_X86_PMU_OP_OPTIONAL(cleanup)
+
+#undef KVM_X86_PMU_OP
+#undef KVM_X86_PMU_OP_OPTIONAL
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index bb0b1ad0fda5..618f529f1c4d 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -51,14 +51,28 @@
 
 static struct kvm_pmu_ops kvm_pmu_ops __read_mostly;
 
+#define KVM_X86_PMU_OP(func)					     \
+	DEFINE_STATIC_CALL_NULL(kvm_x86_pmu_##func,			     \
+				*(((struct kvm_pmu_ops *)0)->func));
+#define KVM_X86_PMU_OP_OPTIONAL KVM_X86_PMU_OP
+#include <asm/kvm-x86-pmu-ops.h>
+
 void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops)
 {
 	memcpy(&kvm_pmu_ops, pmu_ops, sizeof(kvm_pmu_ops));
+
+#define __KVM_X86_PMU_OP(func) \
+	static_call_update(kvm_x86_pmu_##func, kvm_pmu_ops.func);
+#define KVM_X86_PMU_OP(func) \
+	WARN_ON(!kvm_pmu_ops.func); __KVM_X86_PMU_OP(func)
+#define KVM_X86_PMU_OP_OPTIONAL __KVM_X86_PMU_OP
+#include <asm/kvm-x86-pmu-ops.h>
+#undef __KVM_X86_PMU_OP
 }
 
 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 void kvm_pmi_trigger_fn(struct irq_work *irq_work)
@@ -225,7 +239,7 @@ 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.pmc_perf_hw_id(pmc);
+		config = static_call(kvm_x86_pmu_pmc_perf_hw_id)(pmc);
 		if (config != PERF_COUNT_HW_MAX)
 			type = PERF_TYPE_HARDWARE;
 	}
@@ -275,7 +289,7 @@ 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.pmc_perf_hw_id(pmc),
+			      static_call(kvm_x86_pmu_pmc_perf_hw_id)(pmc),
 			      !(en_field & 0x2), /* exclude user */
 			      !(en_field & 0x1), /* exclude kernel */
 			      pmi);
@@ -284,7 +298,7 @@ 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;
@@ -306,7 +320,7 @@ 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);
@@ -328,7 +342,7 @@ void kvm_pmu_handle_event(struct kvm_vcpu *vcpu)
 /* check if idx is a valid index to access PMU */
 bool 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)
@@ -378,7 +392,7 @@ 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;
 
@@ -394,22 +408,21 @@ 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);
@@ -417,13 +430,13 @@ 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
@@ -432,7 +445,7 @@ 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)
@@ -440,7 +453,7 @@ 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)
@@ -448,7 +461,7 @@ 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;
@@ -480,14 +493,13 @@ 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);
 }
@@ -517,7 +529,7 @@ static inline bool eventsel_match_perf_hw_id(struct kvm_pmc *pmc,
 	unsigned int config;
 
 	pmc->eventsel &= (ARCH_PERFMON_EVENTSEL_EVENT | ARCH_PERFMON_EVENTSEL_UMASK);
-	config = kvm_pmu_ops.pmc_perf_hw_id(pmc);
+	config = static_call(kvm_x86_pmu_pmc_perf_hw_id)(pmc);
 	pmc->eventsel = old_eventsel;
 	return config == perf_hw_id;
 }
@@ -545,7 +557,7 @@ void kvm_pmu_trigger_event(struct kvm_vcpu *vcpu, u64 perf_hw_id)
 	int i;
 
 	for_each_set_bit(i, pmu->all_valid_pmc_idx, 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_is_enabled(pmc) || !pmc_speculative_in_use(pmc))
 			continue;
-- 
2.35.1.1021.g381101b075-goog

Re: [PATCH v3.1 0/4] KVM: x86: Use static calls to reduce kvm_pmu_ops overhead

[Like Xu]

On 30/3/2022 7:50 am, Sean Christopherson wrote:
> This is a minor iteration on Like's v3 to allow kvm_pmu_ops (the global
> variable, not the struct) be static.  I ran the PMU unit tests and compiled,
> but otherwise it's untested.  Strongly recommend waiting for Like to give
> a thumbs up before applying :-)

Uh, thank you for picking up this optimization and it passes my test cases.

> 
> [*] https://lore.kernel.org/all/20220307115920.51099-1-likexu@tencent.com
> 
> Like Xu (4):
>    KVM: x86: Move kvm_ops_static_call_update() to x86.c
>    KVM: x86: Copy kvm_pmu_ops by value to eliminate layer of indirection
>    KVM: x86: Move .pmu_ops to kvm_x86_init_ops and tag as __initdata
>    KVM: x86: Use static calls to reduce kvm_pmu_ops overhead
> 
>   arch/x86/include/asm/kvm-x86-pmu-ops.h | 31 ++++++++++++
>   arch/x86/include/asm/kvm_host.h        | 17 +------
>   arch/x86/kvm/pmu.c                     | 66 ++++++++++++++++++--------
>   arch/x86/kvm/pmu.h                     |  7 +--
>   arch/x86/kvm/svm/pmu.c                 |  2 +-
>   arch/x86/kvm/svm/svm.c                 |  2 +-
>   arch/x86/kvm/vmx/pmu_intel.c           |  2 +-
>   arch/x86/kvm/vmx/vmx.c                 |  2 +-
>   arch/x86/kvm/x86.c                     | 21 +++++++-
>   9 files changed, 102 insertions(+), 48 deletions(-)
>   create mode 100644 arch/x86/include/asm/kvm-x86-pmu-ops.h
> 
> 
> base-commit: 19164ad08bf668bca4f4bfbaacaa0a47c1b737a6

Re: [PATCH v3.1 0/4] KVM: x86: Use static calls to reduce kvm_pmu_ops overhead

[Paolo Bonzini]

Queued, thanks.

Paolo