Re: [PATCH v5 4/4] KVM: selftests: Add selftest for KVM statistics data binary interface

Ricardo Koller
2021-05-19T22:00:22Z

On Mon, May 17, 2021 at 02:53:14PM +0000, Jing Zhang wrote:
> Add selftest to check KVM stats descriptors validity.
>
> Signed-off-by: Jing Zhang <jingzhangos@google.com>
> ---
> tools/testing/selftests/kvm/.gitignore | 1 +
> tools/testing/selftests/kvm/Makefile | 3 +
> .../testing/selftests/kvm/include/kvm_util.h | 3 +
> .../selftests/kvm/kvm_bin_form_stats.c | 379 ++++++++++++++++++
> tools/testing/selftests/kvm/lib/kvm_util.c | 12 +
> 5 files changed, 398 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/kvm_bin_form_stats.c
>
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index bd83158e0e0b..35796667c944 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -43,3 +43,4 @@
> /memslot_modification_stress_test
> /set_memory_region_test
> /steal_time
> +/kvm_bin_form_stats
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index e439d027939d..2984c86c848a 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -76,6 +76,7 @@ TEST_GEN_PROGS_x86_64 += kvm_page_table_test
> TEST_GEN_PROGS_x86_64 += memslot_modification_stress_test
> TEST_GEN_PROGS_x86_64 += set_memory_region_test
> TEST_GEN_PROGS_x86_64 += steal_time
> +TEST_GEN_PROGS_x86_64 += kvm_bin_form_stats
>
> TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
> TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list-sve
> @@ -87,6 +88,7 @@ TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
> TEST_GEN_PROGS_aarch64 += kvm_page_table_test
> TEST_GEN_PROGS_aarch64 += set_memory_region_test
> TEST_GEN_PROGS_aarch64 += steal_time
> +TEST_GEN_PROGS_aarch64 += kvm_bin_form_stats
>
> TEST_GEN_PROGS_s390x = s390x/memop
> TEST_GEN_PROGS_s390x += s390x/resets
> @@ -96,6 +98,7 @@ TEST_GEN_PROGS_s390x += dirty_log_test
> TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> TEST_GEN_PROGS_s390x += kvm_page_table_test
> TEST_GEN_PROGS_s390x += set_memory_region_test
> +TEST_GEN_PROGS_s390x += kvm_bin_form_stats
>
> TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
> LIBKVM += $(LIBKVM_$(UNAME_M))
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index a8f022794ce3..ee01a67022d9 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -387,4 +387,7 @@ uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc);
> #define GUEST_ASSERT_4(_condition, arg1, arg2, arg3, arg4) \
> __GUEST_ASSERT((_condition), 4, (arg1), (arg2), (arg3), (arg4))
>
> +int vm_get_statsfd(struct kvm_vm *vm);
> +int vcpu_get_statsfd(struct kvm_vm *vm, uint32_t vcpuid);
> +
> #endif /* SELFTEST_KVM_UTIL_H */
> diff --git a/tools/testing/selftests/kvm/kvm_bin_form_stats.c b/tools/testing/selftests/kvm/kvm_bin_form_stats.c
> new file mode 100644
> index 000000000000..dae44397d0f4
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/kvm_bin_form_stats.c
> @@ -0,0 +1,379 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * kvm_bin_form_stats
> + *
> + * Copyright (C) 2021, Google LLC.
> + *
> + * Test the fd-based interface for KVM statistics.
> + */
> +
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <errno.h>
> +
> +#include "test_util.h"
> +
> +#include "kvm_util.h"
> +#include "asm/kvm.h"
> +#include "linux/kvm.h"
> +
> +int vm_stats_test(struct kvm_vm *vm)
> +{
> + ssize_t ret;
> + int i, stats_fd, err = -1;
> + size_t size_desc, size_data = 0;
> + struct kvm_stats_header header;
> + struct kvm_stats_desc *stats_desc, *pdesc;
> + struct kvm_vm_stats_data *stats_data;
> +
> + /* Get fd for VM stats */
> + stats_fd = vm_get_statsfd(vm);
> + if (stats_fd < 0) {
> + perror("Get VM stats fd");
> + return err;
> + }

It seems that the only difference between vm_stats_test and
vcpu_stats_test is what function to use for getting the fd. If that's
the case, it might be better to move all the checks to a common
function.

> + /* Read kvm vm stats header */
> + ret = read(stats_fd, &header, sizeof(header));
> + if (ret != sizeof(header)) {
> + perror("Read VM stats header");
> + goto out_close_fd;
> + }
> + size_desc = sizeof(*stats_desc) + header.name_size;
> + /* Check id string in header, that should start with "kvm" */
> + if (strncmp(header.id, "kvm", 3) ||
> + strlen(header.id) >= KVM_STATS_ID_MAXLEN) {
> + printf("Invalid KVM VM stats type!\n");
> + goto out_close_fd;
> + }
> + /* Sanity check for other fields in header */
> + if (header.count == 0) {
> + err = 0;
> + goto out_close_fd;
> + }

As mentioned by David, it would be better to replace the checks with
TEST_ASSERT's. Most other selftests rely on TEST_ASSERT.

> + /* Check overlap */
> + if (header.desc_offset == 0 || header.data_offset == 0 ||
> + header.desc_offset < sizeof(header) ||
> + header.data_offset < sizeof(header)) {
> + printf("Invalid offset fields in header!\n");
> + goto out_close_fd;
> + }
> + if (header.desc_offset < header.data_offset &&
> + (header.desc_offset + size_desc * header.count >
> + header.data_offset)) {

Could you make the check more strict?

TEST_ASSERT(header.desc_offset + size_desc * header.count == header.data_offset,
"The data block should be at the end of the descriptor block.");

> + printf("VM Descriptor block is overlapped with data block!\n");
> + goto out_close_fd;
> + }
> +
> + /* Allocate memory for stats descriptors */
> + stats_desc = calloc(header.count, size_desc);
> + if (!stats_desc) {
> + perror("Allocate memory for VM stats descriptors");
> + goto out_close_fd;
> + }
> + /* Read kvm vm stats descriptors */
> + ret = pread(stats_fd, stats_desc,
> + size_desc * header.count, header.desc_offset);

You could stress kvm_vm_stats_read() more by calling pread for more
offsets. For example, for every descriptor:

pread(..., header.desc_offset + i * size_desc)

I realize that the typical usage will be to read once for all
descriptors. But kvm_vm_stats_read (and kvm_vcpu_stats_read) need to
handle any offset, and doing so seems to be quite complicated.

Actually, you could stress kvm_vm_stats_read() even more by calling it
for _every_ possible offset (and eventually invalid offsets and sizes).
One easier way to check this is by calling read all descriptors into
some reference buffer using a single pread, and then call it for all
offsets while comparing against the reference buf.

> + if (ret != size_desc * header.count) {
> + perror("Read KVM VM stats descriptors");
> + goto out_free_desc;
> + }
> + /* Sanity check for fields in descriptors */
> + for (i = 0; i < header.count; ++i) {
> + pdesc = (void *)stats_desc + i * size_desc;

cast to (struct kvm_stats_desc *)

> + /* Check type,unit,scale boundaries */
> + if ((pdesc->flags & KVM_STATS_TYPE_MASK) > KVM_STATS_TYPE_MAX) {
> + printf("Unknown KVM stats type!\n");
> + goto out_free_desc;
> + }
> + if ((pdesc->flags & KVM_STATS_UNIT_MASK) > KVM_STATS_UNIT_MAX) {
> + printf("Unknown KVM stats unit!\n");
> + goto out_free_desc;
> + }
> + if ((pdesc->flags & KVM_STATS_SCALE_MASK) >
> + KVM_STATS_SCALE_MAX) {
> + printf("Unknown KVM stats scale!\n");
> + goto out_free_desc;
> + }
> + /* Check exponent for stats unit
> + * Exponent for counter should be greater than or equal to 0
> + * Exponent for unit bytes should be greater than or equal to 0
> + * Exponent for unit seconds should be less than or equal to 0
> + * Exponent for unit clock cycles should be greater than or
> + * equal to 0
> + */
> + switch (pdesc->flags & KVM_STATS_UNIT_MASK) {
> + case KVM_STATS_UNIT_NONE:
> + case KVM_STATS_UNIT_BYTES:
> + case KVM_STATS_UNIT_CYCLES:
> + if (pdesc->exponent < 0) {
> + printf("Unsupported KVM stats unit!\n");
> + goto out_free_desc;
> + }
> + break;
> + case KVM_STATS_UNIT_SECONDS:
> + if (pdesc->exponent > 0) {
> + printf("Unsupported KVM stats unit!\n");
> + goto out_free_desc;
> + }
> + break;

default:
TEST_FAIL("Unexpected unit ...");

> + }
> + /* Check name string */
> + if (strlen(pdesc->name) >= header.name_size) {
> + printf("KVM stats name(%s) too long!\n", pdesc->name);
> + goto out_free_desc;
> + }

Tighter check:

TEST_ASSERT(header.name_size > 0 &&
strlen(pdesc->name) + 1 == header.name_size);

> + /* Check size field, which should not be zero */
> + if (pdesc->size == 0) {
> + printf("KVM descriptor(%s) with size of 0!\n",
> + pdesc->name);
> + goto out_free_desc;
> + }
> + size_data += pdesc->size * sizeof(stats_data->value[0]);
> + }
> + /* Check overlap */
> + if (header.data_offset < header.desc_offset &&
> + header.data_offset + size_data > header.desc_offset) {
> + printf("Data block is overlapped with Descriptor block!\n");
> + goto out_free_desc;
> + }

This won't be needed if you use the suggested TEST_ASSERT (the other
overlap check).

> + /* Check validity of all stats data size */
> + if (size_data < header.count * sizeof(stats_data->value[0])) {
> + printf("Data size is not correct!\n");
> + goto out_free_desc;
> + }

Tighter check:

TEST_ASSERT(size_data == header.count * stats_data->value[0]);

> +
> + /* Allocate memory for stats data */
> + stats_data = malloc(size_data);
> + if (!stats_data) {
> + perror("Allocate memory for VM stats data");
> + goto out_free_desc;
> + }
> + /* Read kvm vm stats data */
> + ret = pread(stats_fd, stats_data, size_data, header.data_offset);
> + if (ret != size_data) {
> + perror("Read KVM VM stats data");
> + goto out_free_data;
> + }
> +
> + err = 0;
> +out_free_data:
> + free(stats_data);
> +out_free_desc:
> + free(stats_desc);
> +out_close_fd:
> + close(stats_fd);
> + return err;
> +}
> +
> +int vcpu_stats_test(struct kvm_vm *vm, int vcpu_id)
> +{
> + ssize_t ret;
> + int i, stats_fd, err = -1;
> + size_t size_desc, size_data = 0;
> + struct kvm_stats_header header;
> + struct kvm_stats_desc *stats_desc, *pdesc;
> + struct kvm_vcpu_stats_data *stats_data;
> +
> + /* Get fd for VCPU stats */
> + stats_fd = vcpu_get_statsfd(vm, vcpu_id);
> + if (stats_fd < 0) {
> + perror("Get VCPU stats fd");
> + return err;
> + }
> + /* Read kvm vcpu stats header */
> + ret = read(stats_fd, &header, sizeof(header));
> + if (ret != sizeof(header)) {
> + perror("Read VCPU stats header");
> + goto out_close_fd;
> + }
> + size_desc = sizeof(*stats_desc) + header.name_size;
> + /* Check id string in header, that should start with "kvm" */
> + if (strncmp(header.id, "kvm", 3) ||
> + strlen(header.id) >= KVM_STATS_ID_MAXLEN) {
> + printf("Invalid KVM VCPU stats type!\n");
> + goto out_close_fd;
> + }
> + /* Sanity check for other fields in header */
> + if (header.count == 0) {
> + err = 0;
> + goto out_close_fd;
> + }
> + /* Check overlap */
> + if (header.desc_offset == 0 || header.data_offset == 0 ||
> + header.desc_offset < sizeof(header) ||
> + header.data_offset < sizeof(header)) {
> + printf("Invalid offset fields in header!\n");
> + goto out_close_fd;
> + }
> + if (header.desc_offset < header.data_offset &&
> + (header.desc_offset + size_desc * header.count >
> + header.data_offset)) {
> + printf("VCPU Descriptor block is overlapped with data block!\n");
> + goto out_close_fd;
> + }

Same as above (tighter check).

> +
> + /* Allocate memory for stats descriptors */
> + stats_desc = calloc(header.count, size_desc);
> + if (!stats_desc) {
> + perror("Allocate memory for VCPU stats descriptors");
> + goto out_close_fd;
> + }
> + /* Read kvm vcpu stats descriptors */
> + ret = pread(stats_fd, stats_desc,
> + size_desc * header.count, header.desc_offset);
> + if (ret != size_desc * header.count) {
> + perror("Read KVM VCPU stats descriptors");
> + goto out_free_desc;
> + }
> + /* Sanity check for fields in descriptors */
> + for (i = 0; i < header.count; ++i) {
> + pdesc = (void *)stats_desc + i * size_desc;
> + /* Check boundaries */
> + if ((pdesc->flags & KVM_STATS_TYPE_MASK) > KVM_STATS_TYPE_MAX) {
> + printf("Unknown KVM stats type!\n");
> + goto out_free_desc;
> + }
> + if ((pdesc->flags & KVM_STATS_UNIT_MASK) > KVM_STATS_UNIT_MAX) {
> + printf("Unknown KVM stats unit!\n");
> + goto out_free_desc;
> + }
> + if ((pdesc->flags & KVM_STATS_SCALE_MASK) >
> + KVM_STATS_SCALE_MAX) {
> + printf("Unknown KVM stats scale!\n");
> + goto out_free_desc;
> + }
> + /* Check exponent for stats unit
> + * Exponent for counter should be greater than or equal to 0
> + * Exponent for unit bytes should be greater than or equal to 0
> + * Exponent for unit seconds should be less than or equal to 0
> + * Exponent for unit clock cycles should be greater than or
> + * equal to 0
> + */
> + switch (pdesc->flags & KVM_STATS_UNIT_MASK) {
> + case KVM_STATS_UNIT_NONE:
> + case KVM_STATS_UNIT_BYTES:
> + case KVM_STATS_UNIT_CYCLES:
> + if (pdesc->exponent < 0) {
> + printf("Unsupported KVM stats unit!\n");
> + goto out_free_desc;
> + }
> + break;
> + case KVM_STATS_UNIT_SECONDS:
> + if (pdesc->exponent > 0) {
> + printf("Unsupported KVM stats unit!\n");
> + goto out_free_desc;
> + }
> + break;
> + }
> + /* Check name string */
> + if (strlen(pdesc->name) >= header.name_size) {
> + printf("KVM stats name(%s) too long!\n", pdesc->name);
> + goto out_free_desc;
> + }
> + /* Check size field, which should not be zero */
> + if (pdesc->size == 0) {
> + printf("KVM descriptor(%s) with size of 0!\n",
> + pdesc->name);
> + goto out_free_desc;
> + }
> + size_data += pdesc->size * sizeof(stats_data->value[0]);
> + }
> + /* Check overlap */
> + if (header.data_offset < header.desc_offset &&
> + header.data_offset + size_data > header.desc_offset) {
> + printf("Data block is overlapped with Descriptor block!\n");
> + goto out_free_desc;
> + }
> + /* Check validity of all stats data size */
> + if (size_data < header.count * sizeof(stats_data->value[0])) {
> + printf("Data size is not correct!\n");
> + goto out_free_desc;
> + }
> +
> + /* Allocate memory for stats data */
> + stats_data = malloc(size_data);
> + if (!stats_data) {
> + perror("Allocate memory for VCPU stats data");
> + goto out_free_desc;
> + }
> + /* Read kvm vcpu stats data */
> + ret = pread(stats_fd, stats_data, size_data, header.data_offset);
> + if (ret != size_data) {
> + perror("Read KVM VCPU stats data");
> + goto out_free_data;
> + }
> +
> + err = 0;
> +out_free_data:
> + free(stats_data);
> +out_free_desc:
> + free(stats_desc);
> +out_close_fd:
> + close(stats_fd);
> + return err;
> +}
> +
> +/*
> + * Usage: kvm_bin_form_stats [#vm] [#vcpu]
> + * The first parameter #vm set the number of VMs being created.
> + * The second parameter #vcpu set the number of VCPUs being created.
> + * By default, 1 VM and 1 VCPU for the VM would be created for testing.
> + */
> +
> +int main(int argc, char *argv[])
> +{
> + int max_vm = 1, max_vcpu = 1, ret, i, j, err = -1;
> + struct kvm_vm **vms;
> +
> + /* Get the number of VMs and VCPUs that would be created for testing. */
> + if (argc > 1) {
> + max_vm = strtol(argv[1], NULL, 0);
> + if (max_vm <= 0)
> + max_vm = 1;
> + }
> + if (argc > 2) {
> + max_vcpu = strtol(argv[2], NULL, 0);
> + if (max_vcpu <= 0)
> + max_vcpu = 1;
> + }
> +
> + /* Check the extension for binary stats */
> + ret = kvm_check_cap(KVM_CAP_STATS_BINARY_FD);
> + if (ret < 0) {
> + printf("Binary form statistics interface is not supported!\n");
> + return err;
> + }
> +
> + /* Create VMs and VCPUs */
> + vms = malloc(sizeof(vms[0]) * max_vm);
> + if (!vms) {
> + perror("Allocate memory for storing VM pointers");
> + return err;
> + }
> + for (i = 0; i < max_vm; ++i) {
> + vms[i] = vm_create(VM_MODE_DEFAULT,
> + DEFAULT_GUEST_PHY_PAGES, O_RDWR);
> + for (j = 0; j < max_vcpu; ++j)
> + vm_vcpu_add(vms[i], j);
> + }
> +
> + /* Check stats read for every VM and VCPU */
> + for (i = 0; i < max_vm; ++i) {
> + if (vm_stats_test(vms[i]))
> + goto out_free_vm;
> + for (j = 0; j < max_vcpu; ++j) {
> + if (vcpu_stats_test(vms[i], j))
> + goto out_free_vm;
> + }
> + }
> +
> + err = 0;
> +out_free_vm:
> + for (i = 0; i < max_vm; ++i)
> + kvm_vm_free(vms[i]);
> + free(vms);
> + return err;
> +}
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index fc83f6c5902d..d9e0b2c8b906 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -2090,3 +2090,15 @@ unsigned int vm_calc_num_guest_pages(enum vm_guest_mode mode, size_t size)
> n = DIV_ROUND_UP(size, vm_guest_mode_params[mode].page_size);
> return vm_adjust_num_guest_pages(mode, n);
> }
> +
> +int vm_get_statsfd(struct kvm_vm *vm)
> +{
> + return ioctl(vm->fd, KVM_STATS_GETFD, NULL);
> +}
> +
> +int vcpu_get_statsfd(struct kvm_vm *vm, uint32_t vcpuid)
> +{
> + struct vcpu *vcpu = vcpu_find(vm, vcpuid);
> +
> + return ioctl(vcpu->fd, KVM_STATS_GETFD, NULL);
> +}
> --
> 2.31.1.751.gd2f1c929bd-goog
>
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