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

Jing Zhang
2021-05-19T22:54:31Z

Hi Ricardo,

On Wed, May 19, 2021 at 5:00 PM Ricardo Koller <ricarkol@google.com> wrote:
>
> 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.
>
Sure, will do that.
> > + /* 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.
>
Will do.
> > + /* 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.");
>
We can't do stricter checks like this. Only the header block is
enforced to be at offset 0.
The descriptor block and data block are not enforced to be adjacent,
they can be at any
offset theoretically. That's why we have the desc_offset and data_offset fields.
> > + 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.
>
Yes, the kvm_{vm,vcpu}_stats_read support read at any offset.
It is a good idea to do stress read and invalid offset read.
Will add those tests.
> > + 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 ...");
>
Will do. thanks.
> > + }
> > + /* 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);
>
The length of name string can be any number less than header.name_size.
We can't add this kind of check here.
> > + /* 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]);
>
Will do this.
> > +
> > + /* 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
> >
> > _______________________________________________
> > kvmarm mailing list
> > kvmarm@lists.cs.columbia.edu
> > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

Thanks,
Jing