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Message-ID: <YNTNaTOsY4lr7Y2Q@t490s>
Date: Thu, 24 Jun 2021 14:22:33 -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>,
Sean Christopherson <seanjc@...gle.com>
Subject: Re: [PATCH 6/9] KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs
file
On Thu, Jun 24, 2021 at 02:13:53PM -0400, Peter Xu wrote:
> Use this file to dump rmap statistic information.
I should still paste some example output here in commit message, which I think
could help on review but I forgot.. There's actually a example in another
commit message, but still, it looks like this (6G guest):
# cat mmu_rmaps_stat
Rmap_Count: 0 1 2-3 4-7 8-15 16-31 32-63 64-127 128-255 256-511 512-1023
Level=4K: 3089171 49005 14016 1363 235 212 15 7 0 0 0
Level=2M: 5951 227 0 0 0 0 0 0 0 0 0
Level=1G: 32 0 0 0 0 0 0 0 0 0 0
We've got another smm address spaces so it's just got doubled.
I'll append that into commit message in the new version (as long as I don't get
a NAK on this patch).
>
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
> arch/x86/kvm/x86.c | 113 +++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 113 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index d2acbea2f3b5..6dfae8375c44 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -30,6 +30,7 @@
> #include "hyperv.h"
> #include "lapic.h"
> #include "xen.h"
> +#include "mmu/mmu_internal.h"
>
> #include <linux/clocksource.h>
> #include <linux/interrupt.h>
> @@ -58,6 +59,7 @@
> #include <linux/sched/isolation.h>
> #include <linux/mem_encrypt.h>
> #include <linux/entry-kvm.h>
> +#include <linux/debugfs.h>
>
> #include <trace/events/kvm.h>
>
> @@ -10763,6 +10765,117 @@ int kvm_arch_post_init_vm(struct kvm *kvm)
> return kvm_mmu_post_init_vm(kvm);
> }
>
> +/*
> + * 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;
> +
> + memset(log, 0, sizeof(log));
> +
> + ret = -ENOMEM;
> + for (i = 0; i < KVM_NR_PAGE_SIZES; i++) {
> + log[i] = kzalloc(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++)
> + if (log[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;
> +}
> +
> static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
> {
> vcpu_load(vcpu);
> --
> 2.31.1
>
--
Peter Xu
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