From 3bcd0662d66fd07e596d2a7445e6b3215631b901 Mon Sep 17 00:00:00 2001
From: Peter Xu <peterx@redhat.com>
Date: Fri, 30 Jul 2021 18:04:52 -0400
Subject: [PATCH] KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file
Use this file to dump rmap statistic information. The statistic is done by
calculating the rmap count and the result is log-2-based.
An example output of this looks like (idle 6GB guest, right after boot linux):
Rmap_Count: 0 1 2-3 4-7 8-15 16-31 32-63 64-127 128-255 256-511 512-1023
Level=4K: 3086676 53045 12330 1272 502 121 76 2 0 0 0
Level=2M: 5947 231 0 0 0 0 0 0 0 0 0
Level=1G: 32 0 0 0 0 0 0 0 0 0 0
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20210730220455.26054-5-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/debugfs.c | 111 ++++++++++++++++++++++++++++++++
arch/x86/kvm/mmu/mmu.c | 20 ++++++
arch/x86/kvm/mmu/mmu_internal.h | 1 +
3 files changed, 132 insertions(+)
diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c
index 95a98413dc326..54a83a7445384 100644
--- a/arch/x86/kvm/debugfs.c
+++ b/arch/x86/kvm/debugfs.c
@@ -7,6 +7,8 @@
#include <linux/kvm_host.h>
#include <linux/debugfs.h>
#include "lapic.h"
+#include "mmu.h"
+#include "mmu/mmu_internal.h"
static int vcpu_get_timer_advance_ns(void *data, u64 *val)
{
@@ -73,3 +75,112 @@ void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_
&vcpu_tsc_scaling_frac_fops);
}
}
+
+/*
+ * This covers statistics <1024 (11=log(1024)+1), which should be enough to
+ * cover RMAP_RECYCLE_THRESHOLD.
+ */
+#define RMAP_LOG_SIZE 11
+
+static const char *kvm_lpage_str[KVM_NR_PAGE_SIZES] = { "4K", "2M", "1G" };
+
+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;
+
+ ret = -ENOMEM;
+ memset(log, 0, sizeof(log));
+ for (i = 0; i < KVM_NR_PAGE_SIZES; i++) {
+ log[i] = kcalloc(RMAP_LOG_SIZE, sizeof(unsigned int), GFP_KERNEL);
+ if (!log[i])
+ goto out;
+ }
+
+ mutex_lock(&kvm->slots_lock);
+ write_lock(&kvm->mmu_lock);
+
+ for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+ slots = __kvm_memslots(kvm, i);
+ for (j = 0; j < slots->used_slots; j++) {
+ slot = &slots->memslots[j];
+ 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 = ffs(pte_list_count(&rmap[l]));
+ if (WARN_ON_ONCE(index >= RMAP_LOG_SIZE))
+ index = RMAP_LOG_SIZE - 1;
+ cur[index]++;
+ }
+ }
+ }
+ }
+
+ write_unlock(&kvm->mmu_lock);
+ mutex_unlock(&kvm->slots_lock);
+
+ /* index=0 counts no rmap; index=1 counts 1 rmap */
+ seq_printf(m, "Rmap_Count:\t0\t1\t");
+ for (i = 2; i < RMAP_LOG_SIZE; i++) {
+ j = 1 << (i - 1);
+ k = (1 << i) - 1;
+ seq_printf(m, "%d-%d\t", j, k);
+ }
+ seq_printf(m, "\n");
+
+ for (i = 0; i < KVM_NR_PAGE_SIZES; i++) {
+ seq_printf(m, "Level=%s:\t", kvm_lpage_str[i]);
+ cur = log[i];
+ for (j = 0; j < RMAP_LOG_SIZE; j++)
+ seq_printf(m, "%d\t", cur[j]);
+ seq_printf(m, "\n");
+ }
+
+ ret = 0;
+out:
+ for (i = 0; i < KVM_NR_PAGE_SIZES; i++)
+ kfree(log[i]);
+
+ return ret;
+}
+
+static int kvm_mmu_rmaps_stat_open(struct inode *inode, struct file *file)
+{
+ struct kvm *kvm = inode->i_private;
+
+ if (!kvm_get_kvm_safe(kvm))
+ return -ENOENT;
+
+ return single_open(file, kvm_mmu_rmaps_stat_show, kvm);
+}
+
+static int kvm_mmu_rmaps_stat_release(struct inode *inode, struct file *file)
+{
+ struct kvm *kvm = inode->i_private;
+
+ kvm_put_kvm(kvm);
+
+ return single_release(inode, file);
+}
+
+static const struct file_operations mmu_rmaps_stat_fops = {
+ .open = kvm_mmu_rmaps_stat_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = kvm_mmu_rmaps_stat_release,
+};
+
+int kvm_arch_create_vm_debugfs(struct kvm *kvm)
+{
+ debugfs_create_file("mmu_rmaps_stat", 0644, kvm->debugfs_dentry, kvm,
+ &mmu_rmaps_stat_fops);
+ return 0;
+}
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index d282ccf5f0c59..5daa8a910e8b3 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1035,6 +1035,26 @@ static bool pte_list_destroy(struct kvm_rmap_head *rmap_head)
return true;
}
+unsigned int pte_list_count(struct kvm_rmap_head *rmap_head)
+{
+ struct pte_list_desc *desc;
+ unsigned int count = 0;
+
+ if (!rmap_head->val)
+ return 0;
+ else if (!(rmap_head->val & 1))
+ return 1;
+
+ desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
+
+ while (desc) {
+ count += desc->spte_count;
+ desc = desc->more;
+ }
+
+ return count;
+}
+
static struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level,
const struct kvm_memory_slot *slot)
{
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index ca7b7595bbfc0..62bb8f758b3f7 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -131,6 +131,7 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
int min_level);
void kvm_flush_remote_tlbs_with_address(struct kvm *kvm,
u64 start_gfn, u64 pages);
+unsigned int pte_list_count(struct kvm_rmap_head *rmap_head);
/*
* Return values of handle_mmio_page_fault, mmu.page_fault, and fast_page_fault().
--
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