diff options
Diffstat (limited to 'tools/testing/selftests/kvm/demand_paging_test.c')
| -rw-r--r-- | tools/testing/selftests/kvm/demand_paging_test.c | 76 |
1 files changed, 63 insertions, 13 deletions
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c index ddacbc6fd1ed..ca258968f6e1 100644 --- a/tools/testing/selftests/kvm/demand_paging_test.c +++ b/tools/testing/selftests/kvm/demand_paging_test.c @@ -77,8 +77,20 @@ static int handle_uffd_page_request(int uffd_mode, int uffd, copy.mode = 0; r = ioctl(uffd, UFFDIO_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 +101,20 @@ 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 +134,9 @@ 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; }; @@ -131,11 +157,12 @@ 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); @@ -148,7 +175,8 @@ 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); @@ -156,9 +184,13 @@ 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]; @@ -171,7 +203,8 @@ 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); } } @@ -188,7 +221,7 @@ 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]); } @@ -212,15 +245,20 @@ 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"); @@ -239,12 +277,14 @@ 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); @@ -256,6 +296,9 @@ 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."); @@ -276,6 +319,13 @@ 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: |