KVM: x86/mmu: Revert "Revert "KVM: MMU: add tracepoint for kvm_mmu_invalidate_all_pages""

Now that the fast invalidate mechanism has been reintroduced, restore
the tracepoint associated with said mechanism.

Note, the name of the tracepoint deviates from the original tracepoint
so as to match KVM's current nomenclature.

This reverts commit 42560fb1f3.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu.c

@@ -5743,6 +5743,7 @@ restart:
 static void kvm_mmu_zap_all_fast(struct kvm *kvm)
 {
 	spin_lock(&kvm->mmu_lock);
+	trace_kvm_mmu_zap_all_fast(kvm);
 	kvm->arch.mmu_valid_gen++;
 
 	kvm_zap_obsolete_pages(kvm);

arch/x86/kvm/mmutrace.h

@@ -282,6 +282,27 @@ TRACE_EVENT(
 	)
 );
 
+TRACE_EVENT(
+	kvm_mmu_zap_all_fast,
+	TP_PROTO(struct kvm *kvm),
+	TP_ARGS(kvm),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, mmu_valid_gen)
+		__field(unsigned int, mmu_used_pages)
+	),
+
+	TP_fast_assign(
+		__entry->mmu_valid_gen = kvm->arch.mmu_valid_gen;
+		__entry->mmu_used_pages = kvm->arch.n_used_mmu_pages;
+	),
+
+	TP_printk("kvm-mmu-valid-gen %lx used_pages %x",
+		  __entry->mmu_valid_gen, __entry->mmu_used_pages
+	)
+);
+
+
 TRACE_EVENT(
 	check_mmio_spte,
 	TP_PROTO(u64 spte, unsigned int kvm_gen, unsigned int spte_gen),