[RFC PATCH 2/5] KVM: x86: Count rmaps per level in a debugfs helper

[Fred Griffoul <griffoul@gmail.com>]

From: Fred Griffoul <fgriffo@amazon.co.uk>

In preparation for storing memslot rmaps in chunks, move the counting
of one memslot level's rmaps into a helper, so that it can later walk
a level one chunk at a time.

No functional change intended.

Signed-off-by: Fred Griffoul <fgriffo@amazon.co.uk>
---
 arch/x86/kvm/debugfs.c | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index 0074a56e45b4..923424011328 100644
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -86,16 +86,30 @@ void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_
 
 static const char *kvm_lpage_str[KVM_NR_PAGE_SIZES] = { "4K", "2M", "1G" };
 
+static void kvm_mmu_rmaps_stat_level(struct kvm_memory_slot *slot, int level,
+				     unsigned int *cur)
+{
+	struct kvm_rmap_head *rmap = slot->arch.rmap[level - PG_LEVEL_4K];
+	unsigned long lpages = kvm_mmu_slot_lpages(slot, level);
+	unsigned int bucket;
+	unsigned long l;
+
+	for (l = 0; l < lpages; l++) {
+		bucket = fls(pte_list_count(&rmap[l]));
+		if (WARN_ON_ONCE(bucket >= RMAP_LOG_SIZE))
+			bucket = RMAP_LOG_SIZE - 1;
+		cur[bucket]++;
+	}
+}
+
 static int kvm_mmu_rmaps_stat_show(struct seq_file *m, void *v)
 {
-	struct kvm_rmap_head *rmap;
 	struct kvm *kvm = m->private;
 	struct kvm_memory_slot *slot;
 	struct kvm_memslots *slots;
-	unsigned int lpage_size, index;
 	/* Still small enough to be on the stack */
 	unsigned int *log[KVM_NR_PAGE_SIZES], *cur;
-	int i, j, k, l, ret;
+	int i, j, k, ret;
 
 	if (!kvm_memslots_have_rmaps(kvm))
 		return 0;
@@ -116,17 +130,8 @@ static int kvm_mmu_rmaps_stat_show(struct seq_file *m, void *v)
 
 		slots = __kvm_memslots(kvm, i);
 		kvm_for_each_memslot(slot, bkt, slots)
-			for (k = 0; k < KVM_NR_PAGE_SIZES; k++) {
-				rmap = slot->arch.rmap[k];
-				lpage_size = kvm_mmu_slot_lpages(slot, k + 1);
-				cur = log[k];
-				for (l = 0; l < lpage_size; l++) {
-					index = fls(pte_list_count(&rmap[l]));
-					if (WARN_ON_ONCE(index >= RMAP_LOG_SIZE))
-						index = RMAP_LOG_SIZE - 1;
-					cur[index]++;
-				}
-			}
+			for (k = 0; k < KVM_NR_PAGE_SIZES; k++)
+				kvm_mmu_rmaps_stat_level(slot, k + 1, log[k]);
 	}
 
 	write_unlock(&kvm->mmu_lock);
-- 
2.47.3