From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/x86/kvm/debugfs.c | 196 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 196 insertions(+) create mode 100644 arch/x86/kvm/debugfs.c (limited to 'arch/x86/kvm/debugfs.c') diff --git a/arch/x86/kvm/debugfs.c b/arch/x86/kvm/debugfs.c new file mode 100644 index 000000000..0074a56e4 --- /dev/null +++ b/arch/x86/kvm/debugfs.c @@ -0,0 +1,196 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel-based Virtual Machine driver for Linux + * + * Copyright 2016 Red Hat, Inc. and/or its affiliates. + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include "lapic.h" +#include "mmu.h" +#include "mmu/mmu_internal.h" + +static int vcpu_get_timer_advance_ns(void *data, u64 *val) +{ + struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data; + *val = vcpu->arch.apic->lapic_timer.timer_advance_ns; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(vcpu_timer_advance_ns_fops, vcpu_get_timer_advance_ns, NULL, "%llu\n"); + +static int vcpu_get_guest_mode(void *data, u64 *val) +{ + struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data; + *val = vcpu->stat.guest_mode; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(vcpu_guest_mode_fops, vcpu_get_guest_mode, NULL, "%lld\n"); + +static int vcpu_get_tsc_offset(void *data, u64 *val) +{ + struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data; + *val = vcpu->arch.tsc_offset; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_offset_fops, vcpu_get_tsc_offset, NULL, "%lld\n"); + +static int vcpu_get_tsc_scaling_ratio(void *data, u64 *val) +{ + struct kvm_vcpu *vcpu = (struct kvm_vcpu *) data; + *val = vcpu->arch.tsc_scaling_ratio; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_scaling_fops, vcpu_get_tsc_scaling_ratio, NULL, "%llu\n"); + +static int vcpu_get_tsc_scaling_frac_bits(void *data, u64 *val) +{ + *val = kvm_caps.tsc_scaling_ratio_frac_bits; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(vcpu_tsc_scaling_frac_fops, vcpu_get_tsc_scaling_frac_bits, NULL, "%llu\n"); + +void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_dentry) +{ + debugfs_create_file("guest_mode", 0444, debugfs_dentry, vcpu, + &vcpu_guest_mode_fops); + debugfs_create_file("tsc-offset", 0444, debugfs_dentry, vcpu, + &vcpu_tsc_offset_fops); + + if (lapic_in_kernel(vcpu)) + debugfs_create_file("lapic_timer_advance_ns", 0444, + debugfs_dentry, vcpu, + &vcpu_timer_advance_ns_fops); + + if (kvm_caps.has_tsc_control) { + debugfs_create_file("tsc-scaling-ratio", 0444, + debugfs_dentry, vcpu, + &vcpu_tsc_scaling_fops); + debugfs_create_file("tsc-scaling-ratio-frac-bits", 0444, + debugfs_dentry, vcpu, + &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; + + if (!kvm_memslots_have_rmaps(kvm)) + return 0; + + 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_arch_nr_memslot_as_ids(kvm); i++) { + int bkt; + + 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]++; + } + } + } + + 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; + int r; + + if (!kvm_get_kvm_safe(kvm)) + return -ENOENT; + + r = single_open(file, kvm_mmu_rmaps_stat_show, kvm); + if (r < 0) + kvm_put_kvm(kvm); + + return r; +} + +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 = { + .owner = THIS_MODULE, + .open = kvm_mmu_rmaps_stat_open, + .read = seq_read, + .llseek = seq_lseek, + .release = kvm_mmu_rmaps_stat_release, +}; + +void kvm_arch_create_vm_debugfs(struct kvm *kvm) +{ + debugfs_create_file("mmu_rmaps_stat", 0644, kvm->debugfs_dentry, kvm, + &mmu_rmaps_stat_fops); +} -- cgit v1.3.1