linux-kernel - [PATCH 1/9] KVM: X86: Add per-vm stat for max rmap list size

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Date:   Thu, 24 Jun 2021 14:13:48 -0400
From:   Peter Xu <peterx@...hat.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Maxim Levitsky <mlevitsk@...hat.com>, peterx@...hat.com,
        Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH 1/9] KVM: X86: Add per-vm stat for max rmap list size

Add a new statistic max_mmu_rmap_size, which stores the maximum size of rmap
for the vm.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/mmu/mmu.c          | 2 ++
 arch/x86/kvm/x86.c              | 1 +
 3 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 55efbacfc244..937bc8021f7a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1138,6 +1138,7 @@ struct kvm_vm_stat {
 	ulong lpages;
 	ulong nx_lpage_splits;
 	ulong max_mmu_page_hash_collisions;
+	ulong max_mmu_rmap_size;
 };
 
 struct kvm_vcpu_stat {
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 5e60b00e8e50..6dd338738118 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2602,6 +2602,8 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 	if (is_shadow_present_pte(*sptep)) {
 		if (!was_rmapped) {
 			rmap_count = rmap_add(vcpu, sptep, gfn);
+			if (rmap_count > vcpu->kvm->stat.max_mmu_rmap_size)
+				vcpu->kvm->stat.max_mmu_rmap_size = rmap_count;
 			if (rmap_count > RMAP_RECYCLE_THRESHOLD)
 				rmap_recycle(vcpu, sptep, gfn);
 		}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bbc4e04e67ad..4aa3cc6ae5d4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -257,6 +257,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 	VM_STAT("largepages", lpages, .mode = 0444),
 	VM_STAT("nx_largepages_splitted", nx_lpage_splits, .mode = 0444),
 	VM_STAT("max_mmu_page_hash_collisions", max_mmu_page_hash_collisions),
+	VM_STAT("max_mmu_rmap_size", max_mmu_rmap_size),
 	{ NULL }
 };
 
-- 
2.31.1