KVM: arm64: Hide kvm_arm_pmu_available behind CONFIG_HW_PERF_EVENTS=y

Move the definition of kvm_arm_pmu_available to pmu-emul.c and, out of
"necessity", hide it behind CONFIG_HW_PERF_EVENTS.  Provide a stub for
the key's wrapper, kvm_arm_support_pmu_v3().  Moving the key's definition
out of perf.c will allow a future commit to delete perf.c entirely.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211111020738.2512932-16-seanjc@google.com

arch/arm64/kernel/image-vars.h

@@ -102,7 +102,9 @@ KVM_NVHE_ALIAS(__stop___kvm_ex_table);
 KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
 
 /* PMU available static key */
+#ifdef CONFIG_HW_PERF_EVENTS
 KVM_NVHE_ALIAS(kvm_arm_pmu_available);
+#endif
 
 /* Position-independent library routines */
 KVM_NVHE_ALIAS_HYP(clear_page, __pi_clear_page);

arch/arm64/kvm/perf.c

@@ -11,8 +11,6 @@
 
 #include <asm/kvm_emulate.h>
 
-DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
-
 void kvm_perf_init(void)
 {
 	kvm_register_perf_callbacks(NULL);

arch/arm64/kvm/pmu-emul.c

@@ -14,6 +14,8 @@
 #include <kvm/arm_pmu.h>
 #include <kvm/arm_vgic.h>
 
+DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
+
 static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_update_pmc_chained(struct kvm_vcpu *vcpu, u64 select_idx);
 static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc);

include/kvm/arm_pmu.h

@@ -13,13 +13,6 @@
 #define ARMV8_PMU_CYCLE_IDX		(ARMV8_PMU_MAX_COUNTERS - 1)
 #define ARMV8_PMU_MAX_COUNTER_PAIRS	((ARMV8_PMU_MAX_COUNTERS + 1) >> 1)
 
-DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
-
-static __always_inline bool kvm_arm_support_pmu_v3(void)
-{
-	return static_branch_likely(&kvm_arm_pmu_available);
-}
-
 #ifdef CONFIG_HW_PERF_EVENTS
 
 struct kvm_pmc {
@@ -36,6 +29,13 @@ struct kvm_pmu {
 	struct irq_work overflow_work;
 };
 
+DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
+
+static __always_inline bool kvm_arm_support_pmu_v3(void)
+{
+	return static_branch_likely(&kvm_arm_pmu_available);
+}
+
 #define kvm_arm_pmu_irq_initialized(v)	((v)->arch.pmu.irq_num >= VGIC_NR_SGIS)
 u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
 void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
@@ -65,6 +65,11 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu);
 struct kvm_pmu {
 };
 
+static inline bool kvm_arm_support_pmu_v3(void)
+{
+	return false;
+}
+
 #define kvm_arm_pmu_irq_initialized(v)	(false)
 static inline u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
 					    u64 select_idx)