Re: [RFC PATCH 2/2] KVM: selftests: Add a test for kvm page table code

Vitaly Kuznetsov
2021-02-08T10:36:13Z

Yanan Wang <wangyanan55@huawei.com> writes:

> This test serves as a performance tester and a bug reproducer for
> kvm page table code (GPA->HPA mappings), so it gives guidance for
> people trying to make some improvement for kvm.
>
> The function guest_code() is designed to cover conditions where a single vcpu
> or multiple vcpus access guest pages within the same memory range, in three
> VM stages(before dirty-logging, during dirty-logging, after dirty-logging).
> Besides, the backing source memory type(ANONYMOUS/THP/HUGETLB) of the tested
> memory region can be specified by users, which means normal page mappings or
> block mappings can be chosen by users to be created in the test.
>
> If use of ANONYMOUS memory is specified, kvm will create page mappings for the
> tested memory region before dirty-logging, and update attributes of the page
> mappings from RO to RW during dirty-logging. If use of THP/HUGETLB memory is
> specified, kvm will create block mappings for the tested memory region before
> dirty-logging, and split the blcok mappings into page mappings during
> dirty-logging, and coalesce the page mappings back into block mappings after
> dirty-logging is stopped.
>
> So in summary, as a performance tester, this test can present the performance
> of kvm creating/updating normal page mappings, or the performance of kvm
> creating/splitting/recovering block mappings, through execution time.
>
> When we need to coalesce the page mappings back to block mappings after dirty
> logging is stopped, we have to firstly invalidate *all* the TLB entries for the
> page mappings right before installation of the block entry, because a TLB conflict
> abort error could occur if we can't invalidate the TLB entries fully. We have
> hit this TLB conflict twice on aarch64 software implementation and fixed it.
> As this test can imulate process from dirty-logging enabled to dirty-logging
> stopped of a VM with block mappings, so it can also reproduce this TLB conflict
> abort due to inadequate TLB invalidation when coalescing tables.
>
> Signed-off-by: Yanan Wang <wangyanan55@huawei.com>

This looks like a really useful thing, thanks! A few nitpicks below.

> ---
> tools/testing/selftests/kvm/Makefile | 3 +
> .../selftests/kvm/kvm_page_table_test.c | 518 ++++++++++++++++++
> 2 files changed, 521 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/kvm_page_table_test.c
>
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index fe41c6a0fa67..697318019bd4 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -62,6 +62,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test
> TEST_GEN_PROGS_x86_64 += demand_paging_test
> TEST_GEN_PROGS_x86_64 += dirty_log_test
> TEST_GEN_PROGS_x86_64 += dirty_log_perf_test
> +TEST_GEN_PROGS_x86_64 += kvm_page_table_test
> TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
> TEST_GEN_PROGS_x86_64 += set_memory_region_test
> TEST_GEN_PROGS_x86_64 += steal_time
> @@ -71,6 +72,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list-sve
> TEST_GEN_PROGS_aarch64 += demand_paging_test
> TEST_GEN_PROGS_aarch64 += dirty_log_test
> TEST_GEN_PROGS_aarch64 += dirty_log_perf_test
> +TEST_GEN_PROGS_aarch64 += kvm_page_table_test
> TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
> TEST_GEN_PROGS_aarch64 += set_memory_region_test
> TEST_GEN_PROGS_aarch64 += steal_time
> @@ -80,6 +82,7 @@ TEST_GEN_PROGS_s390x += s390x/resets
> TEST_GEN_PROGS_s390x += s390x/sync_regs_test
> TEST_GEN_PROGS_s390x += demand_paging_test
> TEST_GEN_PROGS_s390x += dirty_log_test
> +TEST_GEN_PROGS_s390x += kvm_page_table_test
> TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> TEST_GEN_PROGS_s390x += set_memory_region_test
>
> diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> new file mode 100644
> index 000000000000..b09c05288937
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> @@ -0,0 +1,518 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KVM page table test
> + * Based on dirty_log_test.c
> + * Based on dirty_log_perf_test.c
> + *
> + * Copyright (C) 2018, Red Hat, Inc.
> + * Copyright (C) 2020, Google, Inc.
> + * Copyright (C) 2021, Huawei, Inc.

[Paolo's call but] I think we can drop 'based on .. ' and all but the
last copyright notices as I don't quite see what value this gives. Yes,
when a new test is implemented we use something else as a template but
these are just tests after all.

> + *
> + * Make sure that enough THP/HUGETLB pages have been allocated on systems
> + * to cover the testing memory region before running this program, if you
> + * wish to create block mappings in this test.
> + */
> +
> +#define _GNU_SOURCE /* for program_invocation_name */
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <time.h>
> +#include <pthread.h>
> +
> +#include "test_util.h"
> +#include "kvm_util.h"
> +#include "processor.h"
> +#include "guest_modes.h"
> +
> +#define TEST_MEM_SLOT_INDEX 1
> +
> +/* Default size(1GB) of the memory for testing */
> +#define DEFAULT_TEST_MEM_SIZE (1 << 30)
> +
> +/* Default guest test virtual memory offset */
> +#define DEFAULT_GUEST_TEST_MEM 0xc0000000
> +
> +/* Different memory accessing types for a vcpu */
> +enum access_type {
> + ACCESS_TYPE_READ,
> + ACCESS_TYPE_WRITE,
> + NUM_ACCESS_TYPES,
> +};
> +
> +/* Different memory accessing stages for a vcpu */
> +enum test_stage {
> + KVM_CREATE_MAPPINGS,
> + KVM_UPDATE_MAPPINGS,
> + KVM_ADJUST_MAPPINGS,
> + KVM_BEFORE_MAPPINGS,
> + NUM_TEST_STAGES,
> +};
> +
> +static const char * const access_type_string[] = {
> + "ACCESS_TYPE_READ ",
^^^ extra space

> + "ACCESS_TYPE_WRITE",
> +};
> +
> +static const char * const test_stage_string[] = {
> + "KVM_CREATE_MAPPINGS",
> + "KVM_UPDATE_MAPPINGS",
> + "KVM_ADJUST_MAPPINGS",
> + "KVM_BEFORE_MAPPINGS",
> +};
> +

It would probably be possible to drop 'test_stage/access_type' enums and
just use something like
for (i = 0; i < sizeof(test_stage_string); i++)
...

for test stage and just a simple boolean for distinguishing read/write
access.

> +struct perf_test_vcpu_args {
> + int vcpu_id;
> + enum access_type vcpu_access_type;
> +};
> +
> +struct perf_test_args {
> + struct kvm_vm *vm;
> + uint64_t guest_test_virt_mem;
> + uint64_t host_page_size;
> + uint64_t host_num_pages;
> + uint64_t block_page_size;
> + uint64_t block_num_pages;
> + uint64_t host_pages_perblock;
> + enum vm_mem_backing_src_type backing_src_type;
> + struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS];
> +};
> +
> +/*
> + * Guest variables. Use addr_gva2hva() if these variables need
> + * to be changed in host.
> + */
> +static enum test_stage guest_test_stage;
> +
> +/* Host variables */
> +static uint32_t nr_vcpus = 1;
> +static struct perf_test_args perf_test_args;
> +static enum test_stage *current_stage;
> +static enum test_stage vcpu_last_completed_stage[KVM_MAX_VCPUS];
> +static bool host_quit;
> +
> +/*
> + * Guest physical memory offset of the testing memory slot.
> + * This will be set to the topmost valid physical address minus
> + * the test memory size.
> + */
> +static uint64_t guest_test_phys_mem;
> +
> +/*
> + * Guest virtual memory offset of the testing memory slot.
> + * Must not conflict with identity mapped test code.
> + */
> +static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
> +
> +static void guest_code(int vcpu_id)
> +{
> + struct perf_test_vcpu_args *vcpu_args = &perf_test_args.vcpu_args[vcpu_id];
> + enum vm_mem_backing_src_type src_type = perf_test_args.backing_src_type;
> + uint64_t host_page_size = perf_test_args.host_page_size;
> + uint64_t host_num_pages = perf_test_args.host_num_pages;
> + uint64_t block_page_size = perf_test_args.block_page_size;
> + uint64_t block_num_pages = perf_test_args.block_num_pages;
> + uint64_t host_pages_perblock = perf_test_args.host_pages_perblock;
> + uint64_t half = host_pages_perblock / 2;
> + enum access_type vcpu_access_type;
> + enum test_stage stage;
> + uint64_t addr;
> + int i, j;
> +
> + /* Make sure vCPU args data structure is not corrupt */
> + GUEST_ASSERT(vcpu_args->vcpu_id == vcpu_id);
> + vcpu_access_type = vcpu_args->vcpu_access_type;
> +
> + while (true) {
> + stage = READ_ONCE(guest_test_stage);
> + addr = perf_test_args.guest_test_virt_mem;
> +
> + switch (stage) {
> + /*
> + * Before dirty-logging, vCPUs concurrently access the first
> + * 8 bytes of pages within the same memory range with different
> + * and random access types(read or write). Then KVM will create
> + * mappings for them (page mappings or block mappings).
> + */
> + case KVM_CREATE_MAPPINGS:
> + for (i = 0; i < block_num_pages; i++) {
> + if (vcpu_access_type == ACCESS_TYPE_READ)
> + READ_ONCE(*(uint64_t *)addr);
> + else
> + *(uint64_t *)addr = 0x0123456789ABCDEF;
> +
> + addr += block_page_size;
> + }
> + break;
> +
> + /*
> + * During dirty-logging, KVM will only update attributes of the
> + * normal page mappings from RO to RW if backing source type is
> + * anonymous, and will split the block mappings into normal page
> + * mappings if backing source type is THP or HUGETLB.
> + */
> + case KVM_UPDATE_MAPPINGS:
> + if (src_type == VM_MEM_SRC_ANONYMOUS) {
> + for (i = 0; i < host_num_pages; i++) {
> + *(uint64_t *)addr = 0x0123456789ABCDEF;
> + addr += host_page_size;
> + }
> + break;
> + }
> +
> + for (i = 0; i < block_num_pages; i++) {
> + /* Write to the first host page of each block */
> + *(uint64_t *)addr = 0x0123456789ABCDEF;
> +
> + /* Create half new page mappings for each block */
> + addr += host_page_size * half;
> + for (j = half; j < host_pages_perblock; j++) {
> + READ_ONCE(*(uint64_t *)addr);
> + addr += host_page_size;
> + }
> + }
> + break;
> +
> + /*
> + * After dirty-logging is stopped, vCPUs concurrently read from
> + * every single host page. Then KVM will coalesce the splitted
> + * page mappings back to block mappings. And a TLB conflict abort
> + * could occur here if TLB entries of the page mappings are not
> + * fully invalidated.
> + */
> + case KVM_ADJUST_MAPPINGS:
> + for (i = 0; i < host_num_pages; i++) {
> + READ_ONCE(*(uint64_t *)addr);
> + addr += host_page_size;
> + }
> + break;
> +
> + default:
> + break;
> + }
> +
> + GUEST_SYNC(1);
> + }
> +}
> +
> +static void *vcpu_worker(void *data)
> +{
> + int ret;
> + struct perf_test_vcpu_args *vcpu_args = data;
> + struct kvm_vm *vm = perf_test_args.vm;
> + int vcpu_id = vcpu_args->vcpu_id;
> + struct kvm_run *run;
> + struct timespec start;
> + struct timespec ts_diff;
> + enum test_stage stage;
> +
> + vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
> + run = vcpu_state(vm, vcpu_id);
> +
> + while (!READ_ONCE(host_quit)) {
> + clock_gettime(CLOCK_MONOTONIC, &start);

CLOCK_MONOTONIC_RAW maybe to avoid NTP corrections? (here and below)

> + ret = _vcpu_run(vm, vcpu_id);
> + ts_diff = timespec_diff_now(start);
> +
> + TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
> +
> + TEST_ASSERT(get_ucall(vm, vcpu_id, NULL) == UCALL_SYNC,
> + "Invalid guest sync status: exit_reason=%s\n",
> + exit_reason_str(run->exit_reason));
> +
> + pr_debug("Got sync event from vCPU %d\n", vcpu_id);
> + stage = READ_ONCE(*current_stage);
> + vcpu_last_completed_stage[vcpu_id] = stage;
> + pr_debug("vCPU %d has completed stage %s\n"
> + "execution time is: %ld.%.9lds\n\n",
> + vcpu_id, test_stage_string[stage],
> + ts_diff.tv_sec, ts_diff.tv_nsec);
> +
> + while (stage == READ_ONCE(*current_stage) &&
> + !READ_ONCE(host_quit)) {}
> + }
> +
> + return NULL;
> +}
> +
> +struct test_params {
> + enum vm_mem_backing_src_type backing_src_type;
> + uint64_t backing_src_granule;
> + uint64_t test_mem_size;
> + uint64_t phys_offset;
> +};
> +
> +static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
> +{
> + struct test_params *p = arg;
> + struct perf_test_vcpu_args *vcpu_args;
> + uint64_t guest_page_size, guest_num_pages, host_page_size;
> + uint64_t block_page_size = p->backing_src_granule;
> + uint64_t test_mem_size = p->test_mem_size, test_num_pages;
> + void * host_test_mem;
> + struct kvm_vm *vm;
> + int vcpu_id;
> +
> + guest_page_size = vm_guest_mode_params[mode].page_size;
> + host_page_size = getpagesize();
> +
> + /*
> + * Ensure that testing memory size is aligned to guest page size,
> + * host page size and block page size, and that block page size
> + * is aligned to host page size.
> + */
> + TEST_ASSERT(test_mem_size % guest_page_size == 0,
> + "Testing memory size is not guest page size aligned.");
> + TEST_ASSERT(test_mem_size % block_page_size == 0,
> + "Testing memory size is not block page size aligned.");
> + TEST_ASSERT(block_page_size % host_page_size == 0,
> + "Block page size is not host page size aligned.");
> +
> + guest_num_pages = test_mem_size / guest_page_size;
> + test_num_pages = test_mem_size / MIN_PAGE_SIZE;
> + vm = vm_create_with_vcpus(mode, nr_vcpus, test_num_pages, 0, guest_code, NULL);
> +
> + if (!p->phys_offset) {
> + guest_test_phys_mem = (vm_get_max_gfn(vm) -
> + guest_num_pages) * guest_page_size;
> + guest_test_phys_mem &= ~(block_page_size - 1);
> + } else {
> + guest_test_phys_mem = p->phys_offset;
> + }
> +
> + /*
> + * Ensure that guest physical offset of the testing memory slot is
> + * block page size aligned, so that block mappings can be created
> + * successfully by KVM.
> + */
> + TEST_ASSERT(guest_test_phys_mem % block_page_size == 0,
> + "Guest physical offset is not block page size aligned.");
> +#ifdef __s390x__
> + /* Align to 1M (segment size) */
> + guest_test_phys_mem &= ~((1 << 20) - 1);
> +#endif
> +
> + /* Set up the shared data structure perf_test_args */
> + perf_test_args.vm = vm;
> + perf_test_args.guest_test_virt_mem = guest_test_virt_mem;
> + perf_test_args.host_page_size = host_page_size;
> + perf_test_args.host_num_pages = test_mem_size / host_page_size;
> + perf_test_args.block_page_size = block_page_size;
> + perf_test_args.block_num_pages = test_mem_size / block_page_size;
> + perf_test_args.host_pages_perblock = block_page_size / host_page_size;
> + perf_test_args.backing_src_type = p->backing_src_type;
> +
> + for(vcpu_id = 0; vcpu_id < KVM_MAX_VCPUS; vcpu_id++) {
> + vcpu_args = &perf_test_args.vcpu_args[vcpu_id];
> + vcpu_args->vcpu_id = vcpu_id;
> + vcpu_args->vcpu_access_type = random() % NUM_ACCESS_TYPES;

I would've avoided using random here so that testing results are more
stable. I.e. with a small number of vCPUs (say: 2) it may really make a
difference if this will turn out being 'read'/'read' or
'read'/'write'. Would it be OK if we just do

vcpu_args->vcpu_access_type = vcpu_id % NUM_ACCESS_TYPES;

instead?

> + pr_debug("Set access type of vCPU %d as %s\n",
> + access_type_string[vcpu_args->vcpu_access_type]);
> +
> + vcpu_last_completed_stage[vcpu_id] = NUM_TEST_STAGES;
> + }
> +
> + /* Add an extra memory slot with specified backing source type */
> + vm_userspace_mem_region_add(vm, p->backing_src_type,
> + guest_test_phys_mem,
> + TEST_MEM_SLOT_INDEX,
> + guest_num_pages, 0);
> +
> + /* Do mapping for the testing memory slot */
> + virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages, 0);
> +
> + /* Cache the HVA pointer of the region */
> + host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
> +
> + /* Export shared structure perf_test_args to guest */
> + ucall_init(vm, NULL);
> + sync_global_to_guest(vm, perf_test_args);
> +
> + current_stage = addr_gva2hva(vm, (vm_vaddr_t)(&guest_test_stage));
> + *current_stage = NUM_TEST_STAGES;
> +
> + pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
> + pr_info("Testing backing source type: %s\n",
> + vm_mem_backing_src_type_string(p->backing_src_type));
> + pr_info("Testing backing source granule: 0x%lx\n", block_page_size);
> + pr_info("Testing memory size: 0x%lx\n", test_mem_size);
> + pr_info("Guest physical test memory offset: 0x%lx\n",
> + guest_test_phys_mem);
> + pr_info("Host virtual test memory offset: 0x%lx\n",
> + (uint64_t)host_test_mem);
> + pr_info("Number of testing vCPUs: %d\n", nr_vcpus);
> +
> + return vm;
> +}
> +
> +static void run_test(enum vm_guest_mode mode, void *arg)
> +{
> + pthread_t *vcpu_threads;
> + struct kvm_vm *vm;
> + int vcpu_id;
> + enum test_stage stage;
> + struct timespec start;
> + struct timespec ts_diff;
> +
> + /* Create VM with vCPUs and make some pre-initialization */
> + vm = pre_init_before_test(mode, arg);
> +
> + vcpu_threads = malloc(nr_vcpus * sizeof(*vcpu_threads));
> + TEST_ASSERT(vcpu_threads, "Memory allocation failed");
> +
> + host_quit = false;
> + stage = KVM_BEFORE_MAPPINGS;
> + *current_stage = stage;
> +
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> + pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
> + &perf_test_args.vcpu_args[vcpu_id]);
> + }
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> + while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
> + pr_debug("Waiting for vCPU %d to complete stage %s\n",
> + vcpu_id, test_stage_string[stage]);
> + }
> + pr_info("Started all vCPUs successfully\n");
> +
> + /* Test the stage of KVM creating mappings */
> + clock_gettime(CLOCK_MONOTONIC, &start);
> + stage = KVM_CREATE_MAPPINGS;
> + *current_stage = stage;
> +
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> + while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
> + pr_debug("Waiting for vCPU %d to complete stage %s\n",
> + vcpu_id, test_stage_string[stage]);
> + }
> +
> + ts_diff = timespec_diff_now(start);
> + pr_info("KVM_CREATE_MAPPINGS: total execution time: %ld.%.9lds\n\n",
> + ts_diff.tv_sec, ts_diff.tv_nsec);
> +
> + /* Test the stage of KVM updating mappings */
> + vm_mem_region_set_flags(vm, TEST_MEM_SLOT_INDEX, KVM_MEM_LOG_DIRTY_PAGES);
> +
> + clock_gettime(CLOCK_MONOTONIC, &start);
> + stage = KVM_UPDATE_MAPPINGS;
> + *current_stage = stage;
> +
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> + while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
> + pr_debug("Waiting for vCPU %d to complete stage %s\n",
> + vcpu_id, test_stage_string[stage]);
> + }
> +
> + ts_diff = timespec_diff_now(start);
> + pr_info("KVM_UPDATE_MAPPINGS: total execution time: %ld.%.9lds\n\n",
> + ts_diff.tv_sec, ts_diff.tv_nsec);
> +
> + /* Test the stage of KVM adjusting mappings */
> + vm_mem_region_set_flags(vm, TEST_MEM_SLOT_INDEX, 0);
> +
> + clock_gettime(CLOCK_MONOTONIC, &start);
> + stage = KVM_ADJUST_MAPPINGS;
> + *current_stage = stage;
> +
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> + while (READ_ONCE(vcpu_last_completed_stage[vcpu_id]) != stage)
> + pr_debug("Waiting for vCPU %d to complete stage %s\n",
> + vcpu_id, test_stage_string[stage]);
> + }
> +
> + ts_diff = timespec_diff_now(start);
> + pr_info("KVM_ADJUST_MAPPINGS: total execution time: %ld.%.9lds\n\n",
> + ts_diff.tv_sec, ts_diff.tv_nsec);
> +
> + /* Tell the vcpu thread to quit */
> + host_quit = true;
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++)
> + pthread_join(vcpu_threads[vcpu_id], NULL);
> +
> + free(vcpu_threads);
> + ucall_uninit(vm);
> + kvm_vm_free(vm);
> +}
> +
> +static void vm_mem_backing_src_types_help(void)
> +{
> + int i;
> +
> + printf(" -t: specify backing source type of the testing memory region\n"
> + " (default: VM_MEM_SRC_ANONYMOUS)\n"
> + " Backing source type IDs:\n");
> +
> + for (i = 0; i < NUM_VM_BACKING_SRC_TYPES; i++)
> + printf(" %d: %s\n", i, vm_mem_backing_src_type_string(i));
> +}
> +
> +static void help(char *name)
> +{
> + puts("");
> + printf("usage: %s [-h] [-m mode] [-t type] [-g granule] [-p offset] "
> + "[-s size] [-v vcpus]\n", name);
> + puts("");
> + guest_modes_help();
> + vm_mem_backing_src_types_help();
> + printf(" -g: specify granule of the backing source pages. e.g. 2M or 1G.\n"
> + " (default: host page size)\n");
> + printf(" -p: specify guest physical test memory offset\n"
> + " must be aligned to granule of the backing source pages.\n"
> + " Warning: a low offset can conflict with the loaded test code.\n");
> + printf(" -s: specify size of the memory region for testing. e.g. 10M or 3G.\n"
> + " must be aligned to granule of the backing source pages.\n"
> + " (default: 1G)\n");
> + printf(" -v: specify the number of vCPUs to run\n"
> + " (default: 1)\n");
> + puts("");
> + exit(0);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
> + struct test_params p = {
> + .backing_src_type = VM_MEM_SRC_ANONYMOUS,
> + .backing_src_granule = getpagesize(),
> + .test_mem_size = DEFAULT_TEST_MEM_SIZE,
> + };
> + int opt, type;
> +
> + guest_modes_append_default();
> +
> + while ((opt = getopt(argc, argv, "hm:t:g:p:s:v:")) != -1) {
> + switch (opt) {
> + case 'm':
> + guest_modes_cmdline(optarg);
> + break;
> + case 't':
> + type = strtoul(optarg, NULL, 10);
> + TEST_ASSERT(type < NUM_VM_BACKING_SRC_TYPES,
> + "Backing source type ID %d too big", type);
> + p.backing_src_type = type;
> + break;
> + case 'g':
> + p.backing_src_granule = parse_size(optarg);
> + break;
> + case 'p':
> + p.phys_offset = strtoull(optarg, NULL, 0);
> + break;
> + case 's':
> + p.test_mem_size = parse_size(optarg);
> + break;
> + case 'v':
> + nr_vcpus = atoi(optarg);
> + TEST_ASSERT(nr_vcpus > 0 && nr_vcpus <= max_vcpus,
> + "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
> + break;
> + case 'h':
> + default:
> + help(argv[0]);
> + break;
> + }
> + }
> +
> + for_each_guest_mode(run_test, &p);
> +
> + return 0;
> +}

--
Vitaly