kvm: Support for querying fd-based stats

Add support for querying fd-based KVM stats - as introduced by Linux kernel
commit:

cb082bfab59a ("KVM: stats: Add fd-based API to read binary stats data")

This allows the user to analyze the behavior of the VM without access
to debugfs.

Signed-off-by: Mark Kanda <mark.kanda@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Mark Kanda 2022-02-15 09:04:33 -06:00 committed by Paolo Bonzini
parent b9f88dc071
commit cc01a3f4ca
2 changed files with 393 additions and 1 deletions

View File

@ -47,6 +47,7 @@
#include "kvm-cpus.h"
#include "hw/boards.h"
#include "monitor/stats.h"
/* This check must be after config-host.h is included */
#ifdef CONFIG_EVENTFD
@ -2310,6 +2311,9 @@ bool kvm_dirty_ring_enabled(void)
return kvm_state->kvm_dirty_ring_size ? true : false;
}
static void query_stats_cb(StatsResultList **result, StatsTarget target, Error **errp);
static void query_stats_schemas_cb(StatsSchemaList **result, Error **errp);
static int kvm_init(MachineState *ms)
{
MachineClass *mc = MACHINE_GET_CLASS(ms);
@ -2638,6 +2642,10 @@ static int kvm_init(MachineState *ms)
}
}
if (kvm_check_extension(kvm_state, KVM_CAP_BINARY_STATS_FD)) {
add_stats_callbacks(query_stats_cb, query_stats_schemas_cb);
}
return 0;
err:
@ -3697,3 +3705,387 @@ static void kvm_type_init(void)
}
type_init(kvm_type_init);
typedef struct StatsArgs {
union StatsResultsType {
StatsResultList **stats;
StatsSchemaList **schema;
} result;
Error **errp;
} StatsArgs;
static StatsList *add_kvmstat_entry(struct kvm_stats_desc *pdesc,
uint64_t *stats_data,
StatsList *stats_list,
Error **errp)
{
Stats *stats;
uint64List *val_list = NULL;
/* Only add stats that we understand. */
switch (pdesc->flags & KVM_STATS_TYPE_MASK) {
case KVM_STATS_TYPE_CUMULATIVE:
case KVM_STATS_TYPE_INSTANT:
case KVM_STATS_TYPE_PEAK:
case KVM_STATS_TYPE_LINEAR_HIST:
case KVM_STATS_TYPE_LOG_HIST:
break;
default:
return stats_list;
}
switch (pdesc->flags & KVM_STATS_UNIT_MASK) {
case KVM_STATS_UNIT_NONE:
case KVM_STATS_UNIT_BYTES:
case KVM_STATS_UNIT_CYCLES:
case KVM_STATS_UNIT_SECONDS:
break;
default:
return stats_list;
}
switch (pdesc->flags & KVM_STATS_BASE_MASK) {
case KVM_STATS_BASE_POW10:
case KVM_STATS_BASE_POW2:
break;
default:
return stats_list;
}
/* Alloc and populate data list */
stats = g_new0(Stats, 1);
stats->name = g_strdup(pdesc->name);
stats->value = g_new0(StatsValue, 1);;
if (pdesc->size == 1) {
stats->value->u.scalar = *stats_data;
stats->value->type = QTYPE_QNUM;
} else {
int i;
for (i = 0; i < pdesc->size; i++) {
QAPI_LIST_PREPEND(val_list, stats_data[i]);
}
stats->value->u.list = val_list;
stats->value->type = QTYPE_QLIST;
}
QAPI_LIST_PREPEND(stats_list, stats);
return stats_list;
}
static StatsSchemaValueList *add_kvmschema_entry(struct kvm_stats_desc *pdesc,
StatsSchemaValueList *list,
Error **errp)
{
StatsSchemaValueList *schema_entry = g_new0(StatsSchemaValueList, 1);
schema_entry->value = g_new0(StatsSchemaValue, 1);
switch (pdesc->flags & KVM_STATS_TYPE_MASK) {
case KVM_STATS_TYPE_CUMULATIVE:
schema_entry->value->type = STATS_TYPE_CUMULATIVE;
break;
case KVM_STATS_TYPE_INSTANT:
schema_entry->value->type = STATS_TYPE_INSTANT;
break;
case KVM_STATS_TYPE_PEAK:
schema_entry->value->type = STATS_TYPE_PEAK;
break;
case KVM_STATS_TYPE_LINEAR_HIST:
schema_entry->value->type = STATS_TYPE_LINEAR_HISTOGRAM;
schema_entry->value->bucket_size = pdesc->bucket_size;
schema_entry->value->has_bucket_size = true;
break;
case KVM_STATS_TYPE_LOG_HIST:
schema_entry->value->type = STATS_TYPE_LOG2_HISTOGRAM;
break;
default:
goto exit;
}
switch (pdesc->flags & KVM_STATS_UNIT_MASK) {
case KVM_STATS_UNIT_NONE:
break;
case KVM_STATS_UNIT_BYTES:
schema_entry->value->has_unit = true;
schema_entry->value->unit = STATS_UNIT_BYTES;
break;
case KVM_STATS_UNIT_CYCLES:
schema_entry->value->has_unit = true;
schema_entry->value->unit = STATS_UNIT_CYCLES;
break;
case KVM_STATS_UNIT_SECONDS:
schema_entry->value->has_unit = true;
schema_entry->value->unit = STATS_UNIT_SECONDS;
break;
default:
goto exit;
}
schema_entry->value->exponent = pdesc->exponent;
if (pdesc->exponent) {
switch (pdesc->flags & KVM_STATS_BASE_MASK) {
case KVM_STATS_BASE_POW10:
schema_entry->value->has_base = true;
schema_entry->value->base = 10;
break;
case KVM_STATS_BASE_POW2:
schema_entry->value->has_base = true;
schema_entry->value->base = 2;
break;
default:
goto exit;
}
}
schema_entry->value->name = g_strdup(pdesc->name);
schema_entry->next = list;
return schema_entry;
exit:
g_free(schema_entry->value);
g_free(schema_entry);
return list;
}
/* Cached stats descriptors */
typedef struct StatsDescriptors {
const char *ident; /* cache key, currently the StatsTarget */
struct kvm_stats_desc *kvm_stats_desc;
struct kvm_stats_header *kvm_stats_header;
QTAILQ_ENTRY(StatsDescriptors) next;
} StatsDescriptors;
static QTAILQ_HEAD(, StatsDescriptors) stats_descriptors =
QTAILQ_HEAD_INITIALIZER(stats_descriptors);
/*
* Return the descriptors for 'target', that either have already been read
* or are retrieved from 'stats_fd'.
*/
static StatsDescriptors *find_stats_descriptors(StatsTarget target, int stats_fd,
Error **errp)
{
StatsDescriptors *descriptors;
const char *ident;
struct kvm_stats_desc *kvm_stats_desc;
struct kvm_stats_header *kvm_stats_header;
size_t size_desc;
ssize_t ret;
ident = StatsTarget_str(target);
QTAILQ_FOREACH(descriptors, &stats_descriptors, next) {
if (g_str_equal(descriptors->ident, ident)) {
return descriptors;
}
}
descriptors = g_new0(StatsDescriptors, 1);
/* Read stats header */
kvm_stats_header = g_malloc(sizeof(*kvm_stats_header));
ret = read(stats_fd, kvm_stats_header, sizeof(*kvm_stats_header));
if (ret != sizeof(*kvm_stats_header)) {
error_setg(errp, "KVM stats: failed to read stats header: "
"expected %zu actual %zu",
sizeof(*kvm_stats_header), ret);
return NULL;
}
size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
/* Read stats descriptors */
kvm_stats_desc = g_malloc0_n(kvm_stats_header->num_desc, size_desc);
ret = pread(stats_fd, kvm_stats_desc,
size_desc * kvm_stats_header->num_desc,
kvm_stats_header->desc_offset);
if (ret != size_desc * kvm_stats_header->num_desc) {
error_setg(errp, "KVM stats: failed to read stats descriptors: "
"expected %zu actual %zu",
size_desc * kvm_stats_header->num_desc, ret);
g_free(descriptors);
g_free(kvm_stats_desc);
return NULL;
}
descriptors->kvm_stats_header = kvm_stats_header;
descriptors->kvm_stats_desc = kvm_stats_desc;
descriptors->ident = ident;
QTAILQ_INSERT_TAIL(&stats_descriptors, descriptors, next);
return descriptors;
}
static void query_stats(StatsResultList **result, StatsTarget target,
int stats_fd, Error **errp)
{
struct kvm_stats_desc *kvm_stats_desc;
struct kvm_stats_header *kvm_stats_header;
StatsDescriptors *descriptors;
g_autofree uint64_t *stats_data = NULL;
struct kvm_stats_desc *pdesc;
StatsList *stats_list = NULL;
size_t size_desc, size_data = 0;
ssize_t ret;
int i;
descriptors = find_stats_descriptors(target, stats_fd, errp);
if (!descriptors) {
return;
}
kvm_stats_header = descriptors->kvm_stats_header;
kvm_stats_desc = descriptors->kvm_stats_desc;
size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
/* Tally the total data size; read schema data */
for (i = 0; i < kvm_stats_header->num_desc; ++i) {
pdesc = (void *)kvm_stats_desc + i * size_desc;
size_data += pdesc->size * sizeof(*stats_data);
}
stats_data = g_malloc0(size_data);
ret = pread(stats_fd, stats_data, size_data, kvm_stats_header->data_offset);
if (ret != size_data) {
error_setg(errp, "KVM stats: failed to read data: "
"expected %zu actual %zu", size_data, ret);
return;
}
for (i = 0; i < kvm_stats_header->num_desc; ++i) {
uint64_t *stats;
pdesc = (void *)kvm_stats_desc + i * size_desc;
/* Add entry to the list */
stats = (void *)stats_data + pdesc->offset;
stats_list = add_kvmstat_entry(pdesc, stats, stats_list, errp);
}
if (!stats_list) {
return;
}
switch (target) {
case STATS_TARGET_VM:
add_stats_entry(result, STATS_PROVIDER_KVM, NULL, stats_list);
break;
case STATS_TARGET_VCPU:
add_stats_entry(result, STATS_PROVIDER_KVM,
current_cpu->parent_obj.canonical_path,
stats_list);
break;
default:
break;
}
}
static void query_stats_schema(StatsSchemaList **result, StatsTarget target,
int stats_fd, Error **errp)
{
struct kvm_stats_desc *kvm_stats_desc;
struct kvm_stats_header *kvm_stats_header;
StatsDescriptors *descriptors;
struct kvm_stats_desc *pdesc;
StatsSchemaValueList *stats_list = NULL;
size_t size_desc;
int i;
descriptors = find_stats_descriptors(target, stats_fd, errp);
if (!descriptors) {
return;
}
kvm_stats_header = descriptors->kvm_stats_header;
kvm_stats_desc = descriptors->kvm_stats_desc;
size_desc = sizeof(*kvm_stats_desc) + kvm_stats_header->name_size;
/* Tally the total data size; read schema data */
for (i = 0; i < kvm_stats_header->num_desc; ++i) {
pdesc = (void *)kvm_stats_desc + i * size_desc;
stats_list = add_kvmschema_entry(pdesc, stats_list, errp);
}
add_stats_schema(result, STATS_PROVIDER_KVM, target, stats_list);
}
static void query_stats_vcpu(CPUState *cpu, run_on_cpu_data data)
{
StatsArgs *kvm_stats_args = (StatsArgs *) data.host_ptr;
int stats_fd = kvm_vcpu_ioctl(cpu, KVM_GET_STATS_FD, NULL);
Error *local_err = NULL;
if (stats_fd == -1) {
error_setg_errno(&local_err, errno, "KVM stats: ioctl failed");
error_propagate(kvm_stats_args->errp, local_err);
return;
}
query_stats(kvm_stats_args->result.stats, STATS_TARGET_VCPU, stats_fd,
kvm_stats_args->errp);
close(stats_fd);
}
static void query_stats_schema_vcpu(CPUState *cpu, run_on_cpu_data data)
{
StatsArgs *kvm_stats_args = (StatsArgs *) data.host_ptr;
int stats_fd = kvm_vcpu_ioctl(cpu, KVM_GET_STATS_FD, NULL);
Error *local_err = NULL;
if (stats_fd == -1) {
error_setg_errno(&local_err, errno, "KVM stats: ioctl failed");
error_propagate(kvm_stats_args->errp, local_err);
return;
}
query_stats_schema(kvm_stats_args->result.schema, STATS_TARGET_VCPU, stats_fd,
kvm_stats_args->errp);
close(stats_fd);
}
static void query_stats_cb(StatsResultList **result, StatsTarget target, Error **errp)
{
KVMState *s = kvm_state;
CPUState *cpu;
int stats_fd;
switch (target) {
case STATS_TARGET_VM:
{
stats_fd = kvm_vm_ioctl(s, KVM_GET_STATS_FD, NULL);
if (stats_fd == -1) {
error_setg_errno(errp, errno, "KVM stats: ioctl failed");
return;
}
query_stats(result, target, stats_fd, errp);
close(stats_fd);
break;
}
case STATS_TARGET_VCPU:
{
StatsArgs stats_args;
stats_args.result.stats = result;
stats_args.errp = errp;
CPU_FOREACH(cpu) {
run_on_cpu(cpu, query_stats_vcpu, RUN_ON_CPU_HOST_PTR(&stats_args));
}
break;
}
default:
break;
}
}
void query_stats_schemas_cb(StatsSchemaList **result, Error **errp)
{
StatsArgs stats_args;
KVMState *s = kvm_state;
int stats_fd;
stats_fd = kvm_vm_ioctl(s, KVM_GET_STATS_FD, NULL);
if (stats_fd == -1) {
error_setg_errno(errp, errno, "KVM stats: ioctl failed");
return;
}
query_stats_schema(result, STATS_TARGET_VM, stats_fd, errp);
close(stats_fd);
stats_args.result.schema = result;
stats_args.errp = errp;
run_on_cpu(first_cpu, query_stats_schema_vcpu, RUN_ON_CPU_HOST_PTR(&stats_args));
}

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@ -52,7 +52,7 @@
# Since: 7.1
##
{ 'enum': 'StatsProvider',
'data': [ ] }
'data': [ 'kvm' ] }
##
# @StatsTarget: