Re: [PATCH v6 4/4] KVM: selftests: Add selftest for KVM statistics data binary interface

From: Krish Sadhukhan <krish.sadhukhan@oracle.com>
To: Jing Zhang <jingzhangos@google.com>, KVM <kvm@vger.kernel.org>,
	KVMARM <kvmarm@lists.cs.columbia.edu>,
	LinuxMIPS <linux-mips@vger.kernel.org>,
	KVMPPC <kvm-ppc@vger.kernel.org>,
	LinuxS390 <linux-s390@vger.kernel.org>,
	Linuxkselftest <linux-kselftest@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Will Deacon <will@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Paul Mackerras <paulus@ozlabs.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Jim Mattson <jmattson@google.com>,
	Peter Shier <pshier@google.com>, Oliver Upton <oupton@google.com>,
	David Rientjes <rientjes@google.com>,
	Emanuele Giuseppe Esposito <eesposit@redhat.com>,
	David Matlack <dmatlack@google.com>,
	Ricardo Koller <ricarkol@google.com>
Subject: Re: [PATCH v6 4/4] KVM: selftests: Add selftest for KVM statistics data binary interface
Date: Wed, 26 May 2021 15:34:03 -0700	[thread overview]
Message-ID: <bad9e2cb-0e23-f2ea-054f-23556dbfd7e1@oracle.com> (raw)
In-Reply-To: <20210524151828.4113777-5-jingzhangos@google.com>

On 5/24/21 8:18 AM, Jing Zhang wrote:
> Add selftest to check KVM stats descriptors validity.
>
> Reviewed-by: David Matlack <dmatlack@google.com>
> Reviewed-by: Ricardo Koller <ricarkol@google.com>
> 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        | 216 ++++++++++++++++++
>   tools/testing/selftests/kvm/lib/kvm_util.c    |  12 +
>   5 files changed, 235 insertions(+)
>   create mode 100644 tools/testing/selftests/kvm/kvm_bin_form_stats.c

We should probably follow the naming convention for the majority of the 
files in the kvm directory and name it kvm_stats_read_test.c or 
kvm_stats_test.c or something like that.

>
> 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..09e12c5838af
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/kvm_bin_form_stats.c
> @@ -0,0 +1,216 @@
> +// 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 stats_test(int stats_fd, int size_stat)

The return value is not used by the caller. Perhaps make it a void ?

> +{
> +	ssize_t ret;
> +	int i;
> +	size_t size_desc, size_data = 0;
> +	struct kvm_stats_header header;
> +	struct kvm_stats_desc *stats_desc, *pdesc;
> +	void *stats_data;
> +
> +	/* Read kvm stats header */
> +	ret = read(stats_fd, &header, sizeof(header));
> +	TEST_ASSERT(ret == sizeof(header), "Read stats header");
> +	size_desc = sizeof(*stats_desc) + header.name_size;
> +
> +	/* Check id string in header, that should start with "kvm" */
> +	TEST_ASSERT(!strncmp(header.id, "kvm", 3) &&
> +			strlen(header.id) < KVM_STATS_ID_MAXLEN,
> +			"Invalid KVM stats type");
> +
> +	/* Sanity check for other fields in header */
> +	if (header.count == 0)

Does this need a message as to why count is zero ?

> +		return 0;
> +	/* Check overlap */
> +	TEST_ASSERT(header.desc_offset > 0 && header.data_offset > 0
> +			&& header.desc_offset >= sizeof(header)
> +			&& header.data_offset >= sizeof(header),
> +			"Invalid offset fields in header");
> +	TEST_ASSERT(header.desc_offset > header.data_offset
> +			|| (header.desc_offset + size_desc * header.count <=
> +				header.data_offset),
> +			"Descriptor block is overlapped with data block");
> +
> +	/* Allocate memory for stats descriptors */
> +	stats_desc = calloc(header.count, size_desc);
> +	TEST_ASSERT(stats_desc, "Allocate memory for stats descriptors");
> +	/* Read kvm stats descriptors */
> +	ret = pread(stats_fd, stats_desc,
> +			size_desc * header.count, header.desc_offset);
> +	TEST_ASSERT(ret == size_desc * header.count,
> +			"Read KVM stats descriptors");
> +
> +	/* Sanity check for fields in descriptors */
> +	for (i = 0; i < header.count; ++i) {
> +		pdesc = (void *)stats_desc + i * size_desc;
> +		/* Check type,unit,base boundaries */
> +		TEST_ASSERT((pdesc->flags & KVM_STATS_TYPE_MASK)
> +				<= KVM_STATS_TYPE_MAX, "Unknown KVM stats type");
> +		TEST_ASSERT((pdesc->flags & KVM_STATS_UNIT_MASK)
> +				<= KVM_STATS_UNIT_MAX, "Unknown KVM stats unit");
> +		TEST_ASSERT((pdesc->flags & KVM_STATS_BASE_MASK)
> +				<= KVM_STATS_BASE_MAX, "Unknown KVM stats base");
> +		/* 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:
> +			TEST_ASSERT(pdesc->exponent >= 0,
> +					"Unsupported KVM stats unit");
> +			break;
> +		case KVM_STATS_UNIT_SECONDS:
> +			TEST_ASSERT(pdesc->exponent <= 0,
> +					"Unsupported KVM stats unit");
> +			break;
> +		}
> +		/* Check name string */
> +		TEST_ASSERT(strlen(pdesc->name) < header.name_size,
> +				"KVM stats name(%s) too long", pdesc->name);
> +		/* Check size field, which should not be zero */
> +		TEST_ASSERT(pdesc->size, "KVM descriptor(%s) with size of 0",
> +				pdesc->name);
> +		size_data += pdesc->size * size_stat;
> +	}
> +	/* Check overlap */
> +	TEST_ASSERT(header.data_offset >= header.desc_offset
> +			|| header.data_offset + size_data <= header.desc_offset,
> +			"Data block is overlapped with Descriptor block");
> +	/* Check validity of all stats data size */
> +	TEST_ASSERT(size_data >= header.count * size_stat,
> +			"Data size is not correct");
> +
> +	/* Allocate memory for stats data */
> +	stats_data = malloc(size_data);
> +	TEST_ASSERT(stats_data, "Allocate memory for stats data");
> +	/* Read kvm stats data as a bulk */
> +	ret = pread(stats_fd, stats_data, size_data, header.data_offset);
> +	TEST_ASSERT(ret == size_data, "Read KVM stats data");
> +	/* Read kvm stats data one by one */
> +	size_data = 0;
> +	for (i = 0; i < header.count; ++i) {
> +		pdesc = (void *)stats_desc + i * size_desc;
> +		ret = pread(stats_fd, stats_data, pdesc->size * size_stat,
> +				header.data_offset + size_data);
> +		TEST_ASSERT(ret == pdesc->size * size_stat,
> +				"Read data of KVM stats: %s", pdesc->name);
> +		size_data += pdesc->size * size_stat;
> +	}
> +
> +	free(stats_data);
> +	free(stats_desc);
> +	return 0;
> +}
> +
> +
> +int vm_stats_test(struct kvm_vm *vm)
> +{
> +	int stats_fd;
> +	struct kvm_vm_stats_data *stats_data;
> +
> +	/* Get fd for VM stats */
> +	stats_fd = vm_get_statsfd(vm);
> +	TEST_ASSERT(stats_fd >= 0, "Get VM stats fd");
> +
> +	stats_test(stats_fd, sizeof(stats_data->value[0]));
> +	close(stats_fd);
> +
> +	return 0;
> +}
> +
> +int vcpu_stats_test(struct kvm_vm *vm, int vcpu_id)
> +{
> +	int stats_fd;
> +	struct kvm_vcpu_stats_data *stats_data;
> +
> +	/* Get fd for VCPU stats */
> +	stats_fd = vcpu_get_statsfd(vm, vcpu_id);
> +	TEST_ASSERT(stats_fd >= 0, "Get VCPU stats fd");
> +
> +	stats_test(stats_fd, sizeof(stats_data->value[0]));
> +	close(stats_fd);
> +
> +	return 0;
> +}
> +
> +#define DEFAULT_NUM_VM		4
> +#define DEFAULT_NUM_VCPU	4
> +
> +/*
> + * 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, DEFAULT_NUM_VM VM and DEFAULT_NUM_VCPU VCPU for the VM would be
> + * created for testing.
> + */
> +
> +int main(int argc, char *argv[])
> +{
> +	int max_vm = DEFAULT_NUM_VM, max_vcpu = DEFAULT_NUM_VCPU, ret, i, j;
> +	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 = DEFAULT_NUM_VM;
> +	}
> +	if (argc > 2) {
> +		max_vcpu = strtol(argv[2], NULL, 0);
> +		if (max_vcpu <= 0)
> +			max_vcpu = DEFAULT_NUM_VCPU;
> +	}
> +
> +	/* Check the extension for binary stats */
> +	ret = kvm_check_cap(KVM_CAP_STATS_BINARY_FD);
> +	TEST_ASSERT(ret >= 0,
> +			"Binary form statistics interface is not supported");
> +
> +	/* Create VMs and VCPUs */
> +	vms = malloc(sizeof(vms[0]) * max_vm);
> +	TEST_ASSERT(vms, "Allocate memory for storing VM pointers");
> +	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) {
> +		vm_stats_test(vms[i]);
> +		for (j = 0; j < max_vcpu; ++j)
> +			vcpu_stats_test(vms[i], j);
> +	}
> +

Does it make sense to add one more test case here to test this fd 
interface on a VM or on a VCPU that has been deleted ? For example, how 
does this fd interface behave if we delete the 4th VM and the 4th VCPU 
in the 3rd VM ?

> +	for (i = 0; i < max_vm; ++i)
> +		kvm_vm_free(vms[i]);
> +	free(vms);
> +	return 0;
> +}
> 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);
> +}

Do we need separate functions if they are called just once ?  Or perhaps 
have a single function for the ioctl call, like ?

      int get_stats_fd(int fd, int type)

      {

             return ioctl(fd, type, NULL);

      }