Re: [PATCH v7 2/4] KVM: stats: Add fd-based API to read binary stats data

Fuad Tabba
2021-06-13T15:21:27Z

Hi Jing,

> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index ff205b35719b..eb8fd4a96952 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -38,6 +38,58 @@
> #define VECTORSPACING 0x100 /* for EI/VI mode */
> #endif
>
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC();
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> + .name_size = KVM_STATS_NAME_LEN,
> + .count = ARRAY_SIZE(kvm_vm_stats_desc),
> + .desc_offset = sizeof(struct kvm_stats_header),
> + .data_offset = sizeof(struct kvm_stats_header) +
> + sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> + STATS_DESC_COUNTER("wait_exits"),
> + STATS_DESC_COUNTER("cache_exits"),
> + STATS_DESC_COUNTER("signal_exits"),
> + STATS_DESC_COUNTER("int_exits"),
> + STATS_DESC_COUNTER("cop_unusable_exits"),
> + STATS_DESC_COUNTER("tlbmod_exits"),
> + STATS_DESC_COUNTER("tlbmiss_ld_exits"),
> + STATS_DESC_COUNTER("tlbmiss_st_exits"),
> + STATS_DESC_COUNTER("addrerr_st_exits"),
> + STATS_DESC_COUNTER("addrerr_ld_exits"),
> + STATS_DESC_COUNTER("syscall_exits"),
> + STATS_DESC_COUNTER("resvd_inst_exits"),
> + STATS_DESC_COUNTER("break_inst_exits"),
> + STATS_DESC_COUNTER("trap_inst_exits"),
> + STATS_DESC_COUNTER("msa_fpe_exits"),
> + STATS_DESC_COUNTER("fpe_exits"),
> + STATS_DESC_COUNTER("msa_disabled_exits"),
> + STATS_DESC_COUNTER("flush_dcache_exits"),
> +#ifdef CONFIG_KVM_MIPS_VZ
> + STATS_DESC_COUNTER("vz_gpsi_exits"),
> + STATS_DESC_COUNTER("vz_gsfc_exits"),
> + STATS_DESC_COUNTER("vz_hc_exits"),
> + STATS_DESC_COUNTER("vz_grr_exits"),
> + STATS_DESC_COUNTER("vz_gva_exits"),
> + STATS_DESC_COUNTER("vz_ghfc_exits"),
> + STATS_DESC_COUNTER("vz_gpa_exits"),
> + STATS_DESC_COUNTER("vz_resvd_exits"),
> +#ifdef CONFIG_CPU_LOONGSON64
> + STATS_DESC_COUNTER("vz_cpucfg_exits"),
> +#endif
> +#endif
> + );

I'm not sure if this is because I've applied your patches on a
different base than the one you're using (I'm using 5.13-rc6), but it
seems that CONFIG_KVM_MIPS_VZ isn't there anymore. Moreover, looking
at your earlier patch (v7 1/4), although truncated, it doesn't seem
that your version of arch/mips/include/asm/kvm_host.h has that config
either. Again, could be a user-error on my part, but might be worth
checking.

> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 96d10253218a..8e900c482626 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -214,6 +214,59 @@ EXPORT_SYMBOL_GPL(host_xss);
> u64 __read_mostly supported_xss;
> EXPORT_SYMBOL_GPL(supported_xss);
>
> +struct _kvm_stats_desc kvm_vm_stats_desc[] = DEFINE_VM_STATS_DESC(
> + STATS_DESC_COUNTER("mmu_shadow_zapped"),
> + STATS_DESC_COUNTER("mmu_pte_write"),
> + STATS_DESC_COUNTER("mmu_pde_zapped"),
> + STATS_DESC_COUNTER("mmu_flooded"),
> + STATS_DESC_COUNTER("mmu_recycled"),
> + STATS_DESC_COUNTER("mmu_cache_miss"),
> + STATS_DESC_ICOUNTER("mmu_unsync"),
> + STATS_DESC_ICOUNTER("largepages"),
> + STATS_DESC_ICOUNTER("nx_largepages_splits"),
> + STATS_DESC_ICOUNTER("max_mmu_page_hash_collisions"));
> +
> +struct _kvm_stats_header kvm_vm_stats_header = {
> + .name_size = KVM_STATS_NAME_LEN,
> + .count = ARRAY_SIZE(kvm_vm_stats_desc),
> + .desc_offset = sizeof(struct kvm_stats_header),
> + .data_offset = sizeof(struct kvm_stats_header) +
> + sizeof(kvm_vm_stats_desc),
> +};
> +
> +struct _kvm_stats_desc kvm_vcpu_stats_desc[] = DEFINE_VCPU_STATS_DESC(
> + STATS_DESC_COUNTER("pf_fixed"),
> + STATS_DESC_COUNTER("pf_guest"),
> + STATS_DESC_COUNTER("tlb_flush"),
> + STATS_DESC_COUNTER("invlpg"),
> + STATS_DESC_COUNTER("exits"),
> + STATS_DESC_COUNTER("io_exits"),
> + STATS_DESC_COUNTER("mmio_exits"),
> + STATS_DESC_COUNTER("signal_exits"),
> + STATS_DESC_COUNTER("irq_window_exits"),
> + STATS_DESC_COUNTER("nmi_window_exits"),
> + STATS_DESC_COUNTER("l1d_flush"),
> + STATS_DESC_COUNTER("halt_exits"),
> + STATS_DESC_COUNTER("request_irq_exits"),
> + STATS_DESC_COUNTER("irq_exits"),
> + STATS_DESC_COUNTER("host_state_reload"),
> + STATS_DESC_COUNTER("fpu_reload"),
> + STATS_DESC_COUNTER("insn_emulation"),
> + STATS_DESC_COUNTER("insn_emulation_fail"),
> + STATS_DESC_COUNTER("hypercalls"),
> + STATS_DESC_COUNTER("irq_injections"),
> + STATS_DESC_COUNTER("nmi_injections"),
> + STATS_DESC_COUNTER("req_event"),
> + STATS_DESC_COUNTER("nested_run"));

Have you deliberately left out directed_yield_attempted and
directed_yield_successful (from struct kvm_vcpu_stat in
arch/x86/include/asm/kvm_host.h), or should they be here as well?

Thanks,
/fuad

> +struct _kvm_stats_header kvm_vcpu_stats_header = {
> + .name_size = KVM_STATS_NAME_LEN,
> + .count = ARRAY_SIZE(kvm_vcpu_stats_desc),
> + .desc_offset = sizeof(struct kvm_stats_header),
> + .data_offset = sizeof(struct kvm_stats_header) +
> + sizeof(kvm_vcpu_stats_desc),
> +};
> +
> struct kvm_stats_debugfs_item debugfs_entries[] = {
> VCPU_STAT("pf_fixed", pf_fixed),
> VCPU_STAT("pf_guest", pf_guest),
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 1870fa928762..873e21af36be 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1240,6 +1240,19 @@ struct kvm_stats_debugfs_item {
> int mode;
> };
>
> +struct _kvm_stats_header {
> + __u32 name_size;
> + __u32 count;
> + __u32 desc_offset;
> + __u32 data_offset;
> +};
> +
> +#define KVM_STATS_NAME_LEN 48
> +struct _kvm_stats_desc {
> + struct kvm_stats_desc desc;
> + char name[KVM_STATS_NAME_LEN];
> +};
> +
> #define KVM_DBGFS_GET_MODE(dbgfs_item) \
> ((dbgfs_item)->mode ? (dbgfs_item)->mode : 0644)
>
> @@ -1253,8 +1266,127 @@ struct kvm_stats_debugfs_item {
> { n, offsetof(struct kvm_vcpu, stat.generic.x), \
> KVM_STAT_VCPU, ## __VA_ARGS__ }
>
> +#define STATS_DESC(stat, type, unit, scale, exp) \
> + { \
> + { \
> + .flags = type | unit | scale, \
> + .exponent = exp, \
> + .size = 1 \
> + }, \
> + .name = stat, \
> + }
> +#define STATS_DESC_CUMULATIVE(name, unit, scale, exponent) \
> + STATS_DESC(name, KVM_STATS_TYPE_CUMULATIVE, unit, scale, exponent)
> +#define STATS_DESC_INSTANT(name, unit, scale, exponent) \
> + STATS_DESC(name, KVM_STATS_TYPE_INSTANT, unit, scale, exponent)
> +
> +/* Cumulative counter */
> +#define STATS_DESC_COUNTER(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_NONE, \
> + KVM_STATS_BASE_POW10, 0)
> +/* Instantaneous counter */
> +#define STATS_DESC_ICOUNTER(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_NONE, \
> + KVM_STATS_BASE_POW10, 0)
> +
> +/* Cumulative clock cycles */
> +#define STATS_DESC_CYCLE(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_CYCLES, \
> + KVM_STATS_BASE_POW10, 0)
> +/* Instantaneous clock cycles */
> +#define STATS_DESC_ICYCLE(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_CYCLES, \
> + KVM_STATS_BASE_POW10, 0)
> +
> +/* Cumulative memory size in Byte */
> +#define STATS_DESC_SIZE_BYTE(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 0)
> +/* Cumulative memory size in KiByte */
> +#define STATS_DESC_SIZE_KBYTE(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 10)
> +/* Cumulative memory size in MiByte */
> +#define STATS_DESC_SIZE_MBYTE(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 20)
> +/* Cumulative memory size in GiByte */
> +#define STATS_DESC_SIZE_GBYTE(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 30)
> +
> +/* Instantaneous memory size in Byte */
> +#define STATS_DESC_ISIZE_BYTE(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 0)
> +/* Instantaneous memory size in KiByte */
> +#define STATS_DESC_ISIZE_KBYTE(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 10)
> +/* Instantaneous memory size in MiByte */
> +#define STATS_DESC_ISIZE_MBYTE(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 20)
> +/* Instantaneous memory size in GiByte */
> +#define STATS_DESC_ISIZE_GBYTE(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_BYTES, \
> + KVM_STATS_BASE_POW2, 30)
> +
> +/* Cumulative time in second */
> +#define STATS_DESC_TIME_SEC(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, 0)
> +/* Cumulative time in millisecond */
> +#define STATS_DESC_TIME_MSEC(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, -3)
> +/* Cumulative time in microsecond */
> +#define STATS_DESC_TIME_USEC(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, -6)
> +/* Cumulative time in nanosecond */
> +#define STATS_DESC_TIME_NSEC(name) \
> + STATS_DESC_CUMULATIVE(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, -9)
> +
> +/* Instantaneous time in second */
> +#define STATS_DESC_ITIME_SEC(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, 0)
> +/* Instantaneous time in millisecond */
> +#define STATS_DESC_ITIME_MSEC(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, -3)
> +/* Instantaneous time in microsecond */
> +#define STATS_DESC_ITIME_USEC(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, -6)
> +/* Instantaneous time in nanosecond */
> +#define STATS_DESC_ITIME_NSEC(name) \
> + STATS_DESC_INSTANT(name, KVM_STATS_UNIT_SECONDS, \
> + KVM_STATS_BASE_POW10, -9)
> +
> +#define DEFINE_VM_STATS_DESC(...) { \
> + STATS_DESC_COUNTER("remote_tlb_flush"), \
> + ## __VA_ARGS__ \
> +}
> +
> +#define DEFINE_VCPU_STATS_DESC(...) { \
> + STATS_DESC_COUNTER("halt_successful_poll"), \
> + STATS_DESC_COUNTER("halt_attempted_poll"), \
> + STATS_DESC_COUNTER("halt_poll_invalid"), \
> + STATS_DESC_COUNTER("halt_wakeup"), \
> + STATS_DESC_TIME_NSEC("halt_poll_success_ns"), \
> + STATS_DESC_TIME_NSEC("halt_poll_fail_ns"), \
> + ## __VA_ARGS__ \
> +}
> +
> extern struct kvm_stats_debugfs_item debugfs_entries[];
> extern struct dentry *kvm_debugfs_dir;
> +extern struct _kvm_stats_header kvm_vm_stats_header;
> +extern struct _kvm_stats_header kvm_vcpu_stats_header;
> +extern struct _kvm_stats_desc kvm_vm_stats_desc[];
> +extern struct _kvm_stats_desc kvm_vcpu_stats_desc[];
>
> #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
> static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 3fd9a7e9d90c..dcfa0315e3f9 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1082,6 +1082,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_SGX_ATTRIBUTE 196
> #define KVM_CAP_VM_COPY_ENC_CONTEXT_FROM 197
> #define KVM_CAP_PTP_KVM 198
> +#define KVM_CAP_STATS_BINARY_FD 199
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
> @@ -1898,4 +1899,53 @@ struct kvm_dirty_gfn {
> #define KVM_BUS_LOCK_DETECTION_OFF (1 << 0)
> #define KVM_BUS_LOCK_DETECTION_EXIT (1 << 1)
>
> +#define KVM_STATS_ID_MAXLEN 64
> +
> +struct kvm_stats_header {
> + char id[KVM_STATS_ID_MAXLEN];
> + __u32 name_size;
> + __u32 count;
> + __u32 desc_offset;
> + __u32 data_offset;
> +};
> +
> +#define KVM_STATS_TYPE_SHIFT 0
> +#define KVM_STATS_TYPE_MASK (0xF << KVM_STATS_TYPE_SHIFT)
> +#define KVM_STATS_TYPE_CUMULATIVE (0x0 << KVM_STATS_TYPE_SHIFT)
> +#define KVM_STATS_TYPE_INSTANT (0x1 << KVM_STATS_TYPE_SHIFT)
> +#define KVM_STATS_TYPE_MAX KVM_STATS_TYPE_INSTANT
> +
> +#define KVM_STATS_UNIT_SHIFT 4
> +#define KVM_STATS_UNIT_MASK (0xF << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_NONE (0x0 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_BYTES (0x1 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_SECONDS (0x2 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_CYCLES (0x3 << KVM_STATS_UNIT_SHIFT)
> +#define KVM_STATS_UNIT_MAX KVM_STATS_UNIT_CYCLES
> +
> +#define KVM_STATS_BASE_SHIFT 8
> +#define KVM_STATS_BASE_MASK (0xF << KVM_STATS_BASE_SHIFT)
> +#define KVM_STATS_BASE_POW10 (0x0 << KVM_STATS_BASE_SHIFT)
> +#define KVM_STATS_BASE_POW2 (0x1 << KVM_STATS_BASE_SHIFT)
> +#define KVM_STATS_BASE_MAX KVM_STATS_BASE_POW2
> +
> +struct kvm_stats_desc {
> + __u32 flags;
> + __s16 exponent;
> + __u16 size;
> + __u32 unused1;
> + __u32 unused2;
> + char name[0];
> +};
> +
> +struct kvm_vm_stats_data {
> + unsigned long value[0];
> +};
> +
> +struct kvm_vcpu_stats_data {
> + __u64 value[0];
> +};
> +
> +#define KVM_GET_STATS_FD _IOR(KVMIO, 0xcc, struct kvm_stats_header)
> +
> #endif /* __LINUX_KVM_H */
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f6ad5b080994..d84bb17bdea8 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -3409,6 +3409,115 @@ static int kvm_vcpu_ioctl_set_sigmask(struct kvm_vcpu *vcpu, sigset_t *sigset)
> return 0;
> }
>
> +static ssize_t kvm_stats_read(char *id, struct _kvm_stats_header *header,
> + struct _kvm_stats_desc *desc, void *stats, size_t size_stats,
> + char __user *user_buffer, size_t size, loff_t *offset)
> +{
> + ssize_t copylen, len, remain = size;
> + size_t size_header, size_desc;
> + loff_t pos = *offset;
> + char __user *dest = user_buffer;
> + void *src;
> +
> + size_header = sizeof(*header);
> + size_desc = header->count * sizeof(*desc);
> +
> + len = KVM_STATS_ID_MAXLEN + size_header + size_desc + size_stats - pos;
> + len = min(len, remain);
> + if (len <= 0)
> + return 0;
> + remain = len;
> +
> + /* Copy kvm stats header id string */
> + copylen = KVM_STATS_ID_MAXLEN - pos;
> + copylen = min(copylen, remain);
> + if (copylen > 0) {
> + src = id + pos;
> + if (copy_to_user(dest, src, copylen))
> + return -EFAULT;
> + remain -= copylen;
> + pos += copylen;
> + dest += copylen;
> + }
> + /* Copy kvm stats header */
> + copylen = KVM_STATS_ID_MAXLEN + size_header - pos;
> + copylen = min(copylen, remain);
> + if (copylen > 0) {
> + src = header + pos - KVM_STATS_ID_MAXLEN;
> + if (copy_to_user(dest, src, copylen))
> + return -EFAULT;
> + remain -= copylen;
> + pos += copylen;
> + dest += copylen;
> + }
> + /* Copy kvm stats descriptors */
> + copylen = header->desc_offset + size_desc - pos;
> + copylen = min(copylen, remain);
> + if (copylen > 0) {
> + src = desc + pos - header->desc_offset;
> + if (copy_to_user(dest, src, copylen))
> + return -EFAULT;
> + remain -= copylen;
> + pos += copylen;
> + dest += copylen;
> + }
> + /* Copy kvm stats values */
> + copylen = header->data_offset + size_stats - pos;
> + copylen = min(copylen, remain);
> + if (copylen > 0) {
> + src = stats + pos - header->data_offset;
> + if (copy_to_user(dest, src, copylen))
> + return -EFAULT;
> + remain -= copylen;
> + pos += copylen;
> + dest += copylen;
> + }
> +
> + *offset = pos;
> + return len;
> +}
> +
> +static ssize_t kvm_vcpu_stats_read(struct file *file, char __user *user_buffer,
> + size_t size, loff_t *offset)
> +{
> + char id[KVM_STATS_ID_MAXLEN];
> + struct kvm_vcpu *vcpu = file->private_data;
> +
> + snprintf(id, sizeof(id), "kvm-%d/vcpu-%d",
> + task_pid_nr(current), vcpu->vcpu_id);
> + return kvm_stats_read(id, &kvm_vcpu_stats_header,
> + &kvm_vcpu_stats_desc[0], &vcpu->stat,
> + sizeof(vcpu->stat), user_buffer, size, offset);
> +}
> +
> +static const struct file_operations kvm_vcpu_stats_fops = {
> + .read = kvm_vcpu_stats_read,
> + .llseek = noop_llseek,
> +};
> +
> +static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu)
> +{
> + int fd;
> + struct file *file;
> + char name[15 + ITOA_MAX_LEN + 1];
> +
> + snprintf(name, sizeof(name), "kvm-vcpu-stats:%d", vcpu->vcpu_id);
> +
> + fd = get_unused_fd_flags(O_CLOEXEC);
> + if (fd < 0)
> + return fd;
> +
> + file = anon_inode_getfile(name, &kvm_vcpu_stats_fops, vcpu, O_RDONLY);
> + if (IS_ERR(file)) {
> + put_unused_fd(fd);
> + return PTR_ERR(file);
> + }
> + file->f_mode |= FMODE_PREAD;
> + fd_install(fd, file);
> +
> + return fd;
> +}
> +
> static long kvm_vcpu_ioctl(struct file *filp,
> unsigned int ioctl, unsigned long arg)
> {
> @@ -3606,6 +3715,10 @@ static long kvm_vcpu_ioctl(struct file *filp,
> r = kvm_arch_vcpu_ioctl_set_fpu(vcpu, fpu);
> break;
> }
> + case KVM_GET_STATS_FD: {
> + r = kvm_vcpu_ioctl_get_stats_fd(vcpu);
> + break;
> + }
> default:
> r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);
> }
> @@ -3864,6 +3977,8 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
> #else
> return 0;
> #endif
> + case KVM_CAP_STATS_BINARY_FD:
> + return 1;
> default:
> break;
> }
> @@ -3967,6 +4082,43 @@ static int kvm_vm_ioctl_enable_cap_generic(struct kvm *kvm,
> }
> }
>
> +static ssize_t kvm_vm_stats_read(struct file *file, char __user *user_buffer,
> + size_t size, loff_t *offset)
> +{
> + char id[KVM_STATS_ID_MAXLEN];
> + struct kvm *kvm = file->private_data;
> +
> + snprintf(id, sizeof(id), "kvm-%d", task_pid_nr(current));
> + return kvm_stats_read(id, &kvm_vm_stats_header, &kvm_vm_stats_desc[0],
> + &kvm->stat, sizeof(kvm->stat), user_buffer, size, offset);
> +}
> +
> +static const struct file_operations kvm_vm_stats_fops = {
> + .read = kvm_vm_stats_read,
> + .llseek = noop_llseek,
> +};
> +
> +static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm)
> +{
> + int fd;
> + struct file *file;
> +
> + fd = get_unused_fd_flags(O_CLOEXEC);
> + if (fd < 0)
> + return fd;
> +
> + file = anon_inode_getfile("kvm-vm-stats",
> + &kvm_vm_stats_fops, kvm, O_RDONLY);
> + if (IS_ERR(file)) {
> + put_unused_fd(fd);
> + return PTR_ERR(file);
> + }
> + file->f_mode |= FMODE_PREAD;
> + fd_install(fd, file);
> +
> + return fd;
> +}
> +
> static long kvm_vm_ioctl(struct file *filp,
> unsigned int ioctl, unsigned long arg)
> {
> @@ -4149,6 +4301,9 @@ static long kvm_vm_ioctl(struct file *filp,
> case KVM_RESET_DIRTY_RINGS:
> r = kvm_vm_ioctl_reset_dirty_pages(kvm);
> break;
> + case KVM_GET_STATS_FD:
> + r = kvm_vm_ioctl_get_stats_fd(kvm);
> + break;
> default:
> r = kvm_arch_vm_ioctl(filp, ioctl, arg);
> }
> --
> 2.32.0.rc1.229.g3e70b5a671-goog
>
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