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1// SPDX-License-Identifier: GPL-2.02/*3 * KVM demand paging test4 * Adapted from dirty_log_test.c5 *6 * Copyright (C) 2018, Red Hat, Inc.7 * Copyright (C) 2019, Google, Inc.8 */9#include <inttypes.h>10#include <stdio.h>11#include <stdlib.h>12#include <time.h>13#include <pthread.h>14#include <linux/userfaultfd.h>15#include <sys/syscall.h>16 17#include "kvm_util.h"18#include "test_util.h"19#include "memstress.h"20#include "guest_modes.h"21#include "ucall_common.h"22#include "userfaultfd_util.h"23 24#ifdef __NR_userfaultfd25 26static int nr_vcpus = 1;27static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;28 29static size_t demand_paging_size;30static char *guest_data_prototype;31 32static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)33{34 struct kvm_vcpu *vcpu = vcpu_args->vcpu;35 int vcpu_idx = vcpu_args->vcpu_idx;36 struct kvm_run *run = vcpu->run;37 struct timespec start;38 struct timespec ts_diff;39 int ret;40 41 clock_gettime(CLOCK_MONOTONIC, &start);42 43 /* Let the guest access its memory */44 ret = _vcpu_run(vcpu);45 TEST_ASSERT(ret == 0, "vcpu_run failed: %d", ret);46 if (get_ucall(vcpu, NULL) != UCALL_SYNC) {47 TEST_ASSERT(false,48 "Invalid guest sync status: exit_reason=%s",49 exit_reason_str(run->exit_reason));50 }51 52 ts_diff = timespec_elapsed(start);53 PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_idx,54 ts_diff.tv_sec, ts_diff.tv_nsec);55}56 57static int handle_uffd_page_request(int uffd_mode, int uffd,58 struct uffd_msg *msg)59{60 pid_t tid = syscall(__NR_gettid);61 uint64_t addr = msg->arg.pagefault.address;62 struct timespec start;63 struct timespec ts_diff;64 int r;65 66 clock_gettime(CLOCK_MONOTONIC, &start);67 68 if (uffd_mode == UFFDIO_REGISTER_MODE_MISSING) {69 struct uffdio_copy copy;70 71 copy.src = (uint64_t)guest_data_prototype;72 copy.dst = addr;73 copy.len = demand_paging_size;74 copy.mode = 0;75 76 r = ioctl(uffd, UFFDIO_COPY, ©);77 /*78 * With multiple vCPU threads fault on a single page and there are79 * multiple readers for the UFFD, at least one of the UFFDIO_COPYs80 * will fail with EEXIST: handle that case without signaling an81 * error.82 *83 * Note that this also suppress any EEXISTs occurring from,84 * e.g., the first UFFDIO_COPY/CONTINUEs on a page. That never85 * happens here, but a realistic VMM might potentially maintain86 * some external state to correctly surface EEXISTs to userspace87 * (or prevent duplicate COPY/CONTINUEs in the first place).88 */89 if (r == -1 && errno != EEXIST) {90 pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d, errno = %d\n",91 addr, tid, errno);92 return r;93 }94 } else if (uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {95 struct uffdio_continue cont = {0};96 97 cont.range.start = addr;98 cont.range.len = demand_paging_size;99 100 r = ioctl(uffd, UFFDIO_CONTINUE, &cont);101 /*102 * With multiple vCPU threads fault on a single page and there are103 * multiple readers for the UFFD, at least one of the UFFDIO_COPYs104 * will fail with EEXIST: handle that case without signaling an105 * error.106 *107 * Note that this also suppress any EEXISTs occurring from,108 * e.g., the first UFFDIO_COPY/CONTINUEs on a page. That never109 * happens here, but a realistic VMM might potentially maintain110 * some external state to correctly surface EEXISTs to userspace111 * (or prevent duplicate COPY/CONTINUEs in the first place).112 */113 if (r == -1 && errno != EEXIST) {114 pr_info("Failed UFFDIO_CONTINUE in 0x%lx, thread %d, errno = %d\n",115 addr, tid, errno);116 return r;117 }118 } else {119 TEST_FAIL("Invalid uffd mode %d", uffd_mode);120 }121 122 ts_diff = timespec_elapsed(start);123 124 PER_PAGE_DEBUG("UFFD page-in %d \t%ld ns\n", tid,125 timespec_to_ns(ts_diff));126 PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",127 demand_paging_size, addr, tid);128 129 return 0;130}131 132struct test_params {133 int uffd_mode;134 bool single_uffd;135 useconds_t uffd_delay;136 int readers_per_uffd;137 enum vm_mem_backing_src_type src_type;138 bool partition_vcpu_memory_access;139};140 141static void prefault_mem(void *alias, uint64_t len)142{143 size_t p;144 145 TEST_ASSERT(alias != NULL, "Alias required for minor faults");146 for (p = 0; p < (len / demand_paging_size); ++p) {147 memcpy(alias + (p * demand_paging_size),148 guest_data_prototype, demand_paging_size);149 }150}151 152static void run_test(enum vm_guest_mode mode, void *arg)153{154 struct memstress_vcpu_args *vcpu_args;155 struct test_params *p = arg;156 struct uffd_desc **uffd_descs = NULL;157 uint64_t uffd_region_size;158 struct timespec start;159 struct timespec ts_diff;160 double vcpu_paging_rate;161 struct kvm_vm *vm;162 int i, num_uffds = 0;163 164 vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,165 p->src_type, p->partition_vcpu_memory_access);166 167 demand_paging_size = get_backing_src_pagesz(p->src_type);168 169 guest_data_prototype = malloc(demand_paging_size);170 TEST_ASSERT(guest_data_prototype,171 "Failed to allocate buffer for guest data pattern");172 memset(guest_data_prototype, 0xAB, demand_paging_size);173 174 if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {175 num_uffds = p->single_uffd ? 1 : nr_vcpus;176 for (i = 0; i < num_uffds; i++) {177 vcpu_args = &memstress_args.vcpu_args[i];178 prefault_mem(addr_gpa2alias(vm, vcpu_args->gpa),179 vcpu_args->pages * memstress_args.guest_page_size);180 }181 }182 183 if (p->uffd_mode) {184 num_uffds = p->single_uffd ? 1 : nr_vcpus;185 uffd_region_size = nr_vcpus * guest_percpu_mem_size / num_uffds;186 187 uffd_descs = malloc(num_uffds * sizeof(struct uffd_desc *));188 TEST_ASSERT(uffd_descs, "Memory allocation failed");189 for (i = 0; i < num_uffds; i++) {190 struct memstress_vcpu_args *vcpu_args;191 void *vcpu_hva;192 193 vcpu_args = &memstress_args.vcpu_args[i];194 195 /* Cache the host addresses of the region */196 vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);197 /*198 * Set up user fault fd to handle demand paging199 * requests.200 */201 uffd_descs[i] = uffd_setup_demand_paging(202 p->uffd_mode, p->uffd_delay, vcpu_hva,203 uffd_region_size,204 p->readers_per_uffd,205 &handle_uffd_page_request);206 }207 }208 209 pr_info("Finished creating vCPUs and starting uffd threads\n");210 211 clock_gettime(CLOCK_MONOTONIC, &start);212 memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);213 pr_info("Started all vCPUs\n");214 215 memstress_join_vcpu_threads(nr_vcpus);216 ts_diff = timespec_elapsed(start);217 pr_info("All vCPU threads joined\n");218 219 if (p->uffd_mode) {220 /* Tell the user fault fd handler threads to quit */221 for (i = 0; i < num_uffds; i++)222 uffd_stop_demand_paging(uffd_descs[i]);223 }224 225 pr_info("Total guest execution time:\t%ld.%.9lds\n",226 ts_diff.tv_sec, ts_diff.tv_nsec);227 228 vcpu_paging_rate = memstress_args.vcpu_args[0].pages /229 ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC);230 pr_info("Per-vcpu demand paging rate:\t%f pgs/sec/vcpu\n",231 vcpu_paging_rate);232 pr_info("Overall demand paging rate:\t%f pgs/sec\n",233 vcpu_paging_rate * nr_vcpus);234 235 memstress_destroy_vm(vm);236 237 free(guest_data_prototype);238 if (p->uffd_mode)239 free(uffd_descs);240}241 242static void help(char *name)243{244 puts("");245 printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-a]\n"246 " [-d uffd_delay_usec] [-r readers_per_uffd] [-b memory]\n"247 " [-s type] [-v vcpus] [-c cpu_list] [-o]\n", name);248 guest_modes_help();249 printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"250 " UFFD registration mode: 'MISSING' or 'MINOR'.\n");251 kvm_print_vcpu_pinning_help();252 printf(" -a: Use a single userfaultfd for all of guest memory, instead of\n"253 " creating one for each region paged by a unique vCPU\n"254 " Set implicitly with -o, and no effect without -u.\n");255 printf(" -d: add a delay in usec to the User Fault\n"256 " FD handler to simulate demand paging\n"257 " overheads. Ignored without -u.\n");258 printf(" -r: Set the number of reader threads per uffd.\n");259 printf(" -b: specify the size of the memory region which should be\n"260 " demand paged by each vCPU. e.g. 10M or 3G.\n"261 " Default: 1G\n");262 backing_src_help("-s");263 printf(" -v: specify the number of vCPUs to run.\n");264 printf(" -o: Overlap guest memory accesses instead of partitioning\n"265 " them into a separate region of memory for each vCPU.\n");266 puts("");267 exit(0);268}269 270int main(int argc, char *argv[])271{272 int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);273 const char *cpulist = NULL;274 struct test_params p = {275 .src_type = DEFAULT_VM_MEM_SRC,276 .partition_vcpu_memory_access = true,277 .readers_per_uffd = 1,278 .single_uffd = false,279 };280 int opt;281 282 guest_modes_append_default();283 284 while ((opt = getopt(argc, argv, "ahom:u:d:b:s:v:c:r:")) != -1) {285 switch (opt) {286 case 'm':287 guest_modes_cmdline(optarg);288 break;289 case 'u':290 if (!strcmp("MISSING", optarg))291 p.uffd_mode = UFFDIO_REGISTER_MODE_MISSING;292 else if (!strcmp("MINOR", optarg))293 p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR;294 TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'.");295 break;296 case 'a':297 p.single_uffd = true;298 break;299 case 'd':300 p.uffd_delay = strtoul(optarg, NULL, 0);301 TEST_ASSERT(p.uffd_delay >= 0, "A negative UFFD delay is not supported.");302 break;303 case 'b':304 guest_percpu_mem_size = parse_size(optarg);305 break;306 case 's':307 p.src_type = parse_backing_src_type(optarg);308 break;309 case 'v':310 nr_vcpus = atoi_positive("Number of vCPUs", optarg);311 TEST_ASSERT(nr_vcpus <= max_vcpus,312 "Invalid number of vcpus, must be between 1 and %d", max_vcpus);313 break;314 case 'c':315 cpulist = optarg;316 break;317 case 'o':318 p.partition_vcpu_memory_access = false;319 p.single_uffd = true;320 break;321 case 'r':322 p.readers_per_uffd = atoi(optarg);323 TEST_ASSERT(p.readers_per_uffd >= 1,324 "Invalid number of readers per uffd %d: must be >=1",325 p.readers_per_uffd);326 break;327 case 'h':328 default:329 help(argv[0]);330 break;331 }332 }333 334 if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&335 !backing_src_is_shared(p.src_type)) {336 TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");337 }338 339 if (cpulist) {340 kvm_parse_vcpu_pinning(cpulist, memstress_args.vcpu_to_pcpu,341 nr_vcpus);342 memstress_args.pin_vcpus = true;343 }344 345 for_each_guest_mode(run_test, &p);346 347 return 0;348}349 350#else /* __NR_userfaultfd */351 352#warning "missing __NR_userfaultfd definition"353 354int main(void)355{356 print_skip("__NR_userfaultfd must be present for userfaultfd test");357 return KSFT_SKIP;358}359 360#endif /* __NR_userfaultfd */361