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-rw-r--r--tools/testing/selftests/kvm/demand_paging_test.c94
1 files changed, 73 insertions, 21 deletions
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index bf3609f718..0202b78f86 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -6,14 +6,10 @@
* Copyright (C) 2018, Red Hat, Inc.
* Copyright (C) 2019, Google, Inc.
*/
-
-#define _GNU_SOURCE /* for pipe2 */
-
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
-#include <poll.h>
#include <pthread.h>
#include <linux/userfaultfd.h>
#include <sys/syscall.h>
@@ -22,6 +18,7 @@
#include "test_util.h"
#include "memstress.h"
#include "guest_modes.h"
+#include "ucall_common.h"
#include "userfaultfd_util.h"
#ifdef __NR_userfaultfd
@@ -77,8 +74,20 @@ static int handle_uffd_page_request(int uffd_mode, int uffd,
copy.mode = 0;
r = ioctl(uffd, UFFDIO_COPY, &copy);
- if (r == -1) {
- pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d with errno: %d\n",
+ /*
+ * With multiple vCPU threads fault on a single page and there are
+ * multiple readers for the UFFD, at least one of the UFFDIO_COPYs
+ * will fail with EEXIST: handle that case without signaling an
+ * error.
+ *
+ * Note that this also suppress any EEXISTs occurring from,
+ * e.g., the first UFFDIO_COPY/CONTINUEs on a page. That never
+ * happens here, but a realistic VMM might potentially maintain
+ * some external state to correctly surface EEXISTs to userspace
+ * (or prevent duplicate COPY/CONTINUEs in the first place).
+ */
+ if (r == -1 && errno != EEXIST) {
+ pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d, errno = %d\n",
addr, tid, errno);
return r;
}
@@ -89,8 +98,20 @@ static int handle_uffd_page_request(int uffd_mode, int uffd,
cont.range.len = demand_paging_size;
r = ioctl(uffd, UFFDIO_CONTINUE, &cont);
- if (r == -1) {
- pr_info("Failed UFFDIO_CONTINUE in 0x%lx from thread %d with errno: %d\n",
+ /*
+ * With multiple vCPU threads fault on a single page and there are
+ * multiple readers for the UFFD, at least one of the UFFDIO_COPYs
+ * will fail with EEXIST: handle that case without signaling an
+ * error.
+ *
+ * Note that this also suppress any EEXISTs occurring from,
+ * e.g., the first UFFDIO_COPY/CONTINUEs on a page. That never
+ * happens here, but a realistic VMM might potentially maintain
+ * some external state to correctly surface EEXISTs to userspace
+ * (or prevent duplicate COPY/CONTINUEs in the first place).
+ */
+ if (r == -1 && errno != EEXIST) {
+ pr_info("Failed UFFDIO_CONTINUE in 0x%lx, thread %d, errno = %d\n",
addr, tid, errno);
return r;
}
@@ -110,7 +131,9 @@ static int handle_uffd_page_request(int uffd_mode, int uffd,
struct test_params {
int uffd_mode;
+ bool single_uffd;
useconds_t uffd_delay;
+ int readers_per_uffd;
enum vm_mem_backing_src_type src_type;
bool partition_vcpu_memory_access;
};
@@ -131,10 +154,12 @@ static void run_test(enum vm_guest_mode mode, void *arg)
struct memstress_vcpu_args *vcpu_args;
struct test_params *p = arg;
struct uffd_desc **uffd_descs = NULL;
+ uint64_t uffd_region_size;
struct timespec start;
struct timespec ts_diff;
+ double vcpu_paging_rate;
struct kvm_vm *vm;
- int i;
+ int i, num_uffds = 0;
vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
p->src_type, p->partition_vcpu_memory_access);
@@ -147,7 +172,8 @@ static void run_test(enum vm_guest_mode mode, void *arg)
memset(guest_data_prototype, 0xAB, demand_paging_size);
if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
- for (i = 0; i < nr_vcpus; i++) {
+ num_uffds = p->single_uffd ? 1 : nr_vcpus;
+ for (i = 0; i < num_uffds; i++) {
vcpu_args = &memstress_args.vcpu_args[i];
prefault_mem(addr_gpa2alias(vm, vcpu_args->gpa),
vcpu_args->pages * memstress_args.guest_page_size);
@@ -155,9 +181,13 @@ static void run_test(enum vm_guest_mode mode, void *arg)
}
if (p->uffd_mode) {
- uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
+ num_uffds = p->single_uffd ? 1 : nr_vcpus;
+ uffd_region_size = nr_vcpus * guest_percpu_mem_size / num_uffds;
+
+ uffd_descs = malloc(num_uffds * sizeof(struct uffd_desc *));
TEST_ASSERT(uffd_descs, "Memory allocation failed");
- for (i = 0; i < nr_vcpus; i++) {
+ for (i = 0; i < num_uffds; i++) {
+ struct memstress_vcpu_args *vcpu_args;
void *vcpu_hva;
vcpu_args = &memstress_args.vcpu_args[i];
@@ -170,7 +200,8 @@ static void run_test(enum vm_guest_mode mode, void *arg)
*/
uffd_descs[i] = uffd_setup_demand_paging(
p->uffd_mode, p->uffd_delay, vcpu_hva,
- vcpu_args->pages * memstress_args.guest_page_size,
+ uffd_region_size,
+ p->readers_per_uffd,
&handle_uffd_page_request);
}
}
@@ -187,15 +218,19 @@ static void run_test(enum vm_guest_mode mode, void *arg)
if (p->uffd_mode) {
/* Tell the user fault fd handler threads to quit */
- for (i = 0; i < nr_vcpus; i++)
+ for (i = 0; i < num_uffds; i++)
uffd_stop_demand_paging(uffd_descs[i]);
}
- pr_info("Total guest execution time: %ld.%.9lds\n",
+ pr_info("Total guest execution time:\t%ld.%.9lds\n",
ts_diff.tv_sec, ts_diff.tv_nsec);
- pr_info("Overall demand paging rate: %f pgs/sec\n",
- memstress_args.vcpu_args[0].pages * nr_vcpus /
- ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC));
+
+ vcpu_paging_rate = memstress_args.vcpu_args[0].pages /
+ ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC);
+ pr_info("Per-vcpu demand paging rate:\t%f pgs/sec/vcpu\n",
+ vcpu_paging_rate);
+ pr_info("Overall demand paging rate:\t%f pgs/sec\n",
+ vcpu_paging_rate * nr_vcpus);
memstress_destroy_vm(vm);
@@ -207,15 +242,20 @@ static void run_test(enum vm_guest_mode mode, void *arg)
static void help(char *name)
{
puts("");
- printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
- " [-b memory] [-s type] [-v vcpus] [-c cpu_list] [-o]\n", name);
+ printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-a]\n"
+ " [-d uffd_delay_usec] [-r readers_per_uffd] [-b memory]\n"
+ " [-s type] [-v vcpus] [-c cpu_list] [-o]\n", name);
guest_modes_help();
printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
" UFFD registration mode: 'MISSING' or 'MINOR'.\n");
kvm_print_vcpu_pinning_help();
+ printf(" -a: Use a single userfaultfd for all of guest memory, instead of\n"
+ " creating one for each region paged by a unique vCPU\n"
+ " Set implicitly with -o, and no effect without -u.\n");
printf(" -d: add a delay in usec to the User Fault\n"
" FD handler to simulate demand paging\n"
" overheads. Ignored without -u.\n");
+ printf(" -r: Set the number of reader threads per uffd.\n");
printf(" -b: specify the size of the memory region which should be\n"
" demand paged by each vCPU. e.g. 10M or 3G.\n"
" Default: 1G\n");
@@ -234,12 +274,14 @@ int main(int argc, char *argv[])
struct test_params p = {
.src_type = DEFAULT_VM_MEM_SRC,
.partition_vcpu_memory_access = true,
+ .readers_per_uffd = 1,
+ .single_uffd = false,
};
int opt;
guest_modes_append_default();
- while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:c:o")) != -1) {
+ while ((opt = getopt(argc, argv, "ahom:u:d:b:s:v:c:r:")) != -1) {
switch (opt) {
case 'm':
guest_modes_cmdline(optarg);
@@ -251,6 +293,9 @@ int main(int argc, char *argv[])
p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR;
TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'.");
break;
+ case 'a':
+ p.single_uffd = true;
+ break;
case 'd':
p.uffd_delay = strtoul(optarg, NULL, 0);
TEST_ASSERT(p.uffd_delay >= 0, "A negative UFFD delay is not supported.");
@@ -271,6 +316,13 @@ int main(int argc, char *argv[])
break;
case 'o':
p.partition_vcpu_memory_access = false;
+ p.single_uffd = true;
+ break;
+ case 'r':
+ p.readers_per_uffd = atoi(optarg);
+ TEST_ASSERT(p.readers_per_uffd >= 1,
+ "Invalid number of readers per uffd %d: must be >=1",
+ p.readers_per_uffd);
break;
case 'h':
default:
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 03:46:31 +0000