[PATCH] KVM: stats: Add VM stat for remote tlb flush requests

[Jing Zhang <jingzhangos@google.com>]

Add a new stat that counts the number of times a remote TLB flush is
requested, regardless of whether it kicks vCPUs out of guest mode. This
allows us to look at how often flushes are initiated.

Original-by: David Matlack <dmatlack@google.com>
Signed-off-by: Jing Zhang <jingzhangos@google.com>
---
 arch/arm64/kvm/mmu.c      | 1 +
 include/linux/kvm_host.h  | 3 ++-
 include/linux/kvm_types.h | 1 +
 virt/kvm/kvm_main.c       | 1 +
 4 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 0625bf2353c2..f5bb235bbb59 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -80,6 +80,7 @@ static bool memslot_is_logging(struct kvm_memory_slot *memslot)
  */
 void kvm_flush_remote_tlbs(struct kvm *kvm)
 {
+	++kvm->stat.generic.remote_tlb_flush_requests;
 	kvm_call_hyp(__kvm_tlb_flush_vmid, &kvm->arch.mmu);
 }
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d447b21cdd73..27cb69e564cb 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1444,7 +1444,8 @@ struct _kvm_stats_desc {
 		KVM_STATS_BASE_POW10, -9, sz)
 
 #define KVM_GENERIC_VM_STATS()						       \
-	STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush)
+	STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush),		       \
+	STATS_DESC_COUNTER(VM_GENERIC, remote_tlb_flush_requests)
 
 #define KVM_GENERIC_VCPU_STATS()					       \
 	STATS_DESC_COUNTER(VCPU_GENERIC, halt_successful_poll),		       \
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index de7fb5f364d8..2237abb93ccd 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -80,6 +80,7 @@ struct kvm_mmu_memory_cache {
 
 struct kvm_vm_stat_generic {
 	u64 remote_tlb_flush;
+	u64 remote_tlb_flush_requests;
 };
 
 struct kvm_vcpu_stat_generic {
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3e67c93ca403..26b77ab98a04 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -318,6 +318,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
 	 */
 	long dirty_count = smp_load_acquire(&kvm->tlbs_dirty);
 
+	++kvm->stat.generic.remote_tlb_flush_requests;
 	/*
 	 * We want to publish modifications to the page tables before reading
 	 * mode. Pairs with a memory barrier in arch-specific code.

base-commit: a3e0b8bd99ab098514bde2434301fa6fde040da2
-- 
2.33.0.rc1.237.g0d66db33f3-goog

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