linux/tools/testing/selftests/kvm/memslot_modification_stress_test.c
David Matlack ef4c9f4f65 KVM: selftests: Fix 32-bit truncation of vm_get_max_gfn()
vm_get_max_gfn() casts vm->max_gfn from a uint64_t to an unsigned int,
which causes the upper 32-bits of the max_gfn to get truncated.

Nobody noticed until now likely because vm_get_max_gfn() is only used
as a mechanism to create a memslot in an unused region of the guest
physical address space (the top), and the top of the 32-bit physical
address space was always good enough.

This fix reveals a bug in memslot_modification_stress_test which was
trying to create a dummy memslot past the end of guest physical memory.
Fix that by moving the dummy memslot lower.

Fixes: 52200d0d94 ("KVM: selftests: Remove duplicate guest mode handling")
Reviewed-by: Venkatesh Srinivas <venkateshs@chromium.org>
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210521173828.1180619-1-dmatlack@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-05-27 07:45:54 -04:00

217 lines
5.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* KVM memslot modification stress test
* Adapted from demand_paging_test.c
*
* Copyright (C) 2018, Red Hat, Inc.
* Copyright (C) 2020, Google, Inc.
*/
#define _GNU_SOURCE /* for program_invocation_name */
#include <stdio.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <asm/unistd.h>
#include <time.h>
#include <poll.h>
#include <pthread.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include <linux/userfaultfd.h>
#include "perf_test_util.h"
#include "processor.h"
#include "test_util.h"
#include "guest_modes.h"
#define DUMMY_MEMSLOT_INDEX 7
#define DEFAULT_MEMSLOT_MODIFICATION_ITERATIONS 10
static int nr_vcpus = 1;
static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
static bool run_vcpus = true;
static void *vcpu_worker(void *data)
{
int ret;
struct perf_test_vcpu_args *vcpu_args =
(struct perf_test_vcpu_args *)data;
int vcpu_id = vcpu_args->vcpu_id;
struct kvm_vm *vm = perf_test_args.vm;
struct kvm_run *run;
vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
run = vcpu_state(vm, vcpu_id);
/* Let the guest access its memory until a stop signal is received */
while (READ_ONCE(run_vcpus)) {
ret = _vcpu_run(vm, vcpu_id);
TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
if (get_ucall(vm, vcpu_id, NULL) == UCALL_SYNC)
continue;
TEST_ASSERT(false,
"Invalid guest sync status: exit_reason=%s\n",
exit_reason_str(run->exit_reason));
}
return NULL;
}
struct memslot_antagonist_args {
struct kvm_vm *vm;
useconds_t delay;
uint64_t nr_modifications;
};
static void add_remove_memslot(struct kvm_vm *vm, useconds_t delay,
uint64_t nr_modifications)
{
const uint64_t pages = 1;
uint64_t gpa;
int i;
/*
* Add the dummy memslot just below the perf_test_util memslot, which is
* at the top of the guest physical address space.
*/
gpa = guest_test_phys_mem - pages * vm_get_page_size(vm);
for (i = 0; i < nr_modifications; i++) {
usleep(delay);
vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, gpa,
DUMMY_MEMSLOT_INDEX, pages, 0);
vm_mem_region_delete(vm, DUMMY_MEMSLOT_INDEX);
}
}
struct test_params {
useconds_t memslot_modification_delay;
uint64_t nr_memslot_modifications;
bool partition_vcpu_memory_access;
};
static void run_test(enum vm_guest_mode mode, void *arg)
{
struct test_params *p = arg;
pthread_t *vcpu_threads;
struct kvm_vm *vm;
int vcpu_id;
vm = perf_test_create_vm(mode, nr_vcpus, guest_percpu_mem_size,
VM_MEM_SRC_ANONYMOUS);
perf_test_args.wr_fract = 1;
vcpu_threads = malloc(nr_vcpus * sizeof(*vcpu_threads));
TEST_ASSERT(vcpu_threads, "Memory allocation failed");
perf_test_setup_vcpus(vm, nr_vcpus, guest_percpu_mem_size,
p->partition_vcpu_memory_access);
/* Export the shared variables to the guest */
sync_global_to_guest(vm, perf_test_args);
pr_info("Finished creating vCPUs\n");
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]);
pr_info("Started all vCPUs\n");
add_remove_memslot(vm, p->memslot_modification_delay,
p->nr_memslot_modifications);
run_vcpus = false;
/* Wait for the vcpu threads to quit */
for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++)
pthread_join(vcpu_threads[vcpu_id], NULL);
pr_info("All vCPU threads joined\n");
ucall_uninit(vm);
kvm_vm_free(vm);
free(vcpu_threads);
}
static void help(char *name)
{
puts("");
printf("usage: %s [-h] [-m mode] [-d delay_usec]\n"
" [-b memory] [-v vcpus] [-o] [-i iterations]\n", name);
guest_modes_help();
printf(" -d: add a delay between each iteration of adding and\n"
" deleting a memslot in usec.\n");
printf(" -b: specify the size of the memory region which should be\n"
" accessed by each vCPU. e.g. 10M or 3G.\n"
" Default: 1G\n");
printf(" -v: specify the number of vCPUs to run.\n");
printf(" -o: Overlap guest memory accesses instead of partitioning\n"
" them into a separate region of memory for each vCPU.\n");
printf(" -i: specify the number of iterations of adding and removing\n"
" a memslot.\n"
" Default: %d\n", DEFAULT_MEMSLOT_MODIFICATION_ITERATIONS);
puts("");
exit(0);
}
int main(int argc, char *argv[])
{
int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
int opt;
struct test_params p = {
.memslot_modification_delay = 0,
.nr_memslot_modifications =
DEFAULT_MEMSLOT_MODIFICATION_ITERATIONS,
.partition_vcpu_memory_access = true
};
guest_modes_append_default();
while ((opt = getopt(argc, argv, "hm:d:b:v:oi:")) != -1) {
switch (opt) {
case 'm':
guest_modes_cmdline(optarg);
break;
case 'd':
p.memslot_modification_delay = strtoul(optarg, NULL, 0);
TEST_ASSERT(p.memslot_modification_delay >= 0,
"A negative delay is not supported.");
break;
case 'b':
guest_percpu_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 'o':
p.partition_vcpu_memory_access = false;
break;
case 'i':
p.nr_memslot_modifications = atoi(optarg);
break;
case 'h':
default:
help(argv[0]);
break;
}
}
for_each_guest_mode(run_test, &p);
return 0;
}