1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KVM dirty logging page splitting test
4 *
5 * Based on dirty_log_perf.c
6 *
7 * Copyright (C) 2018, Red Hat, Inc.
8 * Copyright (C) 2023, Google, Inc.
9 */
10
11 #include <stdio.h>
12 #include <stdlib.h>
13 #include <pthread.h>
14 #include <linux/bitmap.h>
15
16 #include "kvm_util.h"
17 #include "test_util.h"
18 #include "memstress.h"
19 #include "guest_modes.h"
20
21 #define VCPUS 2
22 #define SLOTS 2
23 #define ITERATIONS 2
24
25 static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
26
27 static enum vm_mem_backing_src_type backing_src = VM_MEM_SRC_ANONYMOUS_HUGETLB;
28
29 static u64 dirty_log_manual_caps;
30 static bool host_quit;
31 static int iteration;
32 static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
33
34 struct kvm_page_stats {
35 uint64_t pages_4k;
36 uint64_t pages_2m;
37 uint64_t pages_1g;
38 uint64_t hugepages;
39 };
40
get_page_stats(struct kvm_vm * vm,struct kvm_page_stats * stats,const char * stage)41 static void get_page_stats(struct kvm_vm *vm, struct kvm_page_stats *stats, const char *stage)
42 {
43 stats->pages_4k = vm_get_stat(vm, "pages_4k");
44 stats->pages_2m = vm_get_stat(vm, "pages_2m");
45 stats->pages_1g = vm_get_stat(vm, "pages_1g");
46 stats->hugepages = stats->pages_2m + stats->pages_1g;
47
48 pr_debug("\nPage stats after %s: 4K: %ld 2M: %ld 1G: %ld huge: %ld\n",
49 stage, stats->pages_4k, stats->pages_2m, stats->pages_1g,
50 stats->hugepages);
51 }
52
run_vcpu_iteration(struct kvm_vm * vm)53 static void run_vcpu_iteration(struct kvm_vm *vm)
54 {
55 int i;
56
57 iteration++;
58 for (i = 0; i < VCPUS; i++) {
59 while (READ_ONCE(vcpu_last_completed_iteration[i]) !=
60 iteration)
61 ;
62 }
63 }
64
vcpu_worker(struct memstress_vcpu_args * vcpu_args)65 static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
66 {
67 struct kvm_vcpu *vcpu = vcpu_args->vcpu;
68 int vcpu_idx = vcpu_args->vcpu_idx;
69
70 while (!READ_ONCE(host_quit)) {
71 int current_iteration = READ_ONCE(iteration);
72
73 vcpu_run(vcpu);
74
75 TEST_ASSERT_EQ(get_ucall(vcpu, NULL), UCALL_SYNC);
76
77 vcpu_last_completed_iteration[vcpu_idx] = current_iteration;
78
79 /* Wait for the start of the next iteration to be signaled. */
80 while (current_iteration == READ_ONCE(iteration) &&
81 READ_ONCE(iteration) >= 0 &&
82 !READ_ONCE(host_quit))
83 ;
84 }
85 }
86
run_test(enum vm_guest_mode mode,void * unused)87 static void run_test(enum vm_guest_mode mode, void *unused)
88 {
89 struct kvm_vm *vm;
90 unsigned long **bitmaps;
91 uint64_t guest_num_pages;
92 uint64_t host_num_pages;
93 uint64_t pages_per_slot;
94 int i;
95 uint64_t total_4k_pages;
96 struct kvm_page_stats stats_populated;
97 struct kvm_page_stats stats_dirty_logging_enabled;
98 struct kvm_page_stats stats_dirty_pass[ITERATIONS];
99 struct kvm_page_stats stats_clear_pass[ITERATIONS];
100 struct kvm_page_stats stats_dirty_logging_disabled;
101 struct kvm_page_stats stats_repopulated;
102
103 vm = memstress_create_vm(mode, VCPUS, guest_percpu_mem_size,
104 SLOTS, backing_src, false);
105
106 guest_num_pages = (VCPUS * guest_percpu_mem_size) >> vm->page_shift;
107 guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
108 host_num_pages = vm_num_host_pages(mode, guest_num_pages);
109 pages_per_slot = host_num_pages / SLOTS;
110
111 bitmaps = memstress_alloc_bitmaps(SLOTS, pages_per_slot);
112
113 if (dirty_log_manual_caps)
114 vm_enable_cap(vm, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2,
115 dirty_log_manual_caps);
116
117 /* Start the iterations */
118 iteration = -1;
119 host_quit = false;
120
121 for (i = 0; i < VCPUS; i++)
122 vcpu_last_completed_iteration[i] = -1;
123
124 memstress_start_vcpu_threads(VCPUS, vcpu_worker);
125
126 run_vcpu_iteration(vm);
127 get_page_stats(vm, &stats_populated, "populating memory");
128
129 /* Enable dirty logging */
130 memstress_enable_dirty_logging(vm, SLOTS);
131
132 get_page_stats(vm, &stats_dirty_logging_enabled, "enabling dirty logging");
133
134 while (iteration < ITERATIONS) {
135 run_vcpu_iteration(vm);
136 get_page_stats(vm, &stats_dirty_pass[iteration - 1],
137 "dirtying memory");
138
139 memstress_get_dirty_log(vm, bitmaps, SLOTS);
140
141 if (dirty_log_manual_caps) {
142 memstress_clear_dirty_log(vm, bitmaps, SLOTS, pages_per_slot);
143
144 get_page_stats(vm, &stats_clear_pass[iteration - 1], "clearing dirty log");
145 }
146 }
147
148 /* Disable dirty logging */
149 memstress_disable_dirty_logging(vm, SLOTS);
150
151 get_page_stats(vm, &stats_dirty_logging_disabled, "disabling dirty logging");
152
153 /* Run vCPUs again to fault pages back in. */
154 run_vcpu_iteration(vm);
155 get_page_stats(vm, &stats_repopulated, "repopulating memory");
156
157 /*
158 * Tell the vCPU threads to quit. No need to manually check that vCPUs
159 * have stopped running after disabling dirty logging, the join will
160 * wait for them to exit.
161 */
162 host_quit = true;
163 memstress_join_vcpu_threads(VCPUS);
164
165 memstress_free_bitmaps(bitmaps, SLOTS);
166 memstress_destroy_vm(vm);
167
168 /* Make assertions about the page counts. */
169 total_4k_pages = stats_populated.pages_4k;
170 total_4k_pages += stats_populated.pages_2m * 512;
171 total_4k_pages += stats_populated.pages_1g * 512 * 512;
172
173 /*
174 * Check that all huge pages were split. Since large pages can only
175 * exist in the data slot, and the vCPUs should have dirtied all pages
176 * in the data slot, there should be no huge pages left after splitting.
177 * Splitting happens at dirty log enable time without
178 * KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 and after the first clear pass
179 * with that capability.
180 */
181 if (dirty_log_manual_caps) {
182 TEST_ASSERT_EQ(stats_clear_pass[0].hugepages, 0);
183 TEST_ASSERT_EQ(stats_clear_pass[0].pages_4k, total_4k_pages);
184 TEST_ASSERT_EQ(stats_dirty_logging_enabled.hugepages, stats_populated.hugepages);
185 } else {
186 TEST_ASSERT_EQ(stats_dirty_logging_enabled.hugepages, 0);
187 TEST_ASSERT_EQ(stats_dirty_logging_enabled.pages_4k, total_4k_pages);
188 }
189
190 /*
191 * Once dirty logging is disabled and the vCPUs have touched all their
192 * memory again, the page counts should be the same as they were
193 * right after initial population of memory.
194 */
195 TEST_ASSERT_EQ(stats_populated.pages_4k, stats_repopulated.pages_4k);
196 TEST_ASSERT_EQ(stats_populated.pages_2m, stats_repopulated.pages_2m);
197 TEST_ASSERT_EQ(stats_populated.pages_1g, stats_repopulated.pages_1g);
198 }
199
help(char * name)200 static void help(char *name)
201 {
202 puts("");
203 printf("usage: %s [-h] [-b vcpu bytes] [-s mem type]\n",
204 name);
205 puts("");
206 printf(" -b: specify the size of the memory region which should be\n"
207 " dirtied by each vCPU. e.g. 10M or 3G.\n"
208 " (default: 1G)\n");
209 backing_src_help("-s");
210 puts("");
211 }
212
main(int argc,char * argv[])213 int main(int argc, char *argv[])
214 {
215 int opt;
216
217 TEST_REQUIRE(get_kvm_param_bool("eager_page_split"));
218 TEST_REQUIRE(get_kvm_param_bool("tdp_mmu"));
219
220 while ((opt = getopt(argc, argv, "b:hs:")) != -1) {
221 switch (opt) {
222 case 'b':
223 guest_percpu_mem_size = parse_size(optarg);
224 break;
225 case 'h':
226 help(argv[0]);
227 exit(0);
228 case 's':
229 backing_src = parse_backing_src_type(optarg);
230 break;
231 default:
232 help(argv[0]);
233 exit(1);
234 }
235 }
236
237 if (!is_backing_src_hugetlb(backing_src)) {
238 pr_info("This test will only work reliably with HugeTLB memory. "
239 "It can work with THP, but that is best effort.\n");
240 }
241
242 guest_modes_append_default();
243
244 dirty_log_manual_caps = 0;
245 for_each_guest_mode(run_test, NULL);
246
247 dirty_log_manual_caps =
248 kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
249
250 if (dirty_log_manual_caps) {
251 dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
252 KVM_DIRTY_LOG_INITIALLY_SET);
253 for_each_guest_mode(run_test, NULL);
254 } else {
255 pr_info("Skipping testing with MANUAL_PROTECT as it is not supported");
256 }
257
258 return 0;
259 }
260