Commit 3bcd0662 authored by Peter Xu's avatar Peter Xu Committed by Paolo Bonzini
Browse files

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: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <20210730220455.26054-5-peterx@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 4139b197

arch/x86/kvm/debugfs.c

+111 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/x86/kvm/mmu/mmu.c

+20 −0
Original line number Diff line number Diff line
@@ -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)

{

arch/x86/kvm/mmu/mmu_internal.h

+1 −0
Original line number Diff line number Diff line
@@ -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().