From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- tools/testing/selftests/ring-buffer/.gitignore | 1 + tools/testing/selftests/ring-buffer/Makefile | 7 + tools/testing/selftests/ring-buffer/config | 2 + tools/testing/selftests/ring-buffer/map_test.c | 324 +++++++++++++++++++++++++ 4 files changed, 334 insertions(+) create mode 100644 tools/testing/selftests/ring-buffer/.gitignore create mode 100644 tools/testing/selftests/ring-buffer/Makefile create mode 100644 tools/testing/selftests/ring-buffer/config create mode 100644 tools/testing/selftests/ring-buffer/map_test.c (limited to 'tools/testing/selftests/ring-buffer') diff --git a/tools/testing/selftests/ring-buffer/.gitignore b/tools/testing/selftests/ring-buffer/.gitignore new file mode 100644 index 000000000..3aed1a2a6 --- /dev/null +++ b/tools/testing/selftests/ring-buffer/.gitignore @@ -0,0 +1 @@ +map_test diff --git a/tools/testing/selftests/ring-buffer/Makefile b/tools/testing/selftests/ring-buffer/Makefile new file mode 100644 index 000000000..236057826 --- /dev/null +++ b/tools/testing/selftests/ring-buffer/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0 +CFLAGS += -Wl,-no-as-needed -Wall +CFLAGS += $(KHDR_INCLUDES) + +TEST_GEN_PROGS = map_test + +include ../lib.mk diff --git a/tools/testing/selftests/ring-buffer/config b/tools/testing/selftests/ring-buffer/config new file mode 100644 index 000000000..d936f8f00 --- /dev/null +++ b/tools/testing/selftests/ring-buffer/config @@ -0,0 +1,2 @@ +CONFIG_FTRACE=y +CONFIG_TRACER_SNAPSHOT=y diff --git a/tools/testing/selftests/ring-buffer/map_test.c b/tools/testing/selftests/ring-buffer/map_test.c new file mode 100644 index 000000000..f24677737 --- /dev/null +++ b/tools/testing/selftests/ring-buffer/map_test.c @@ -0,0 +1,324 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Ring-buffer memory mapping tests + * + * Copyright (c) 2024 Vincent Donnefort + */ +#include +#include +#include +#include +#include +#include + +#include + +#include +#include + +#include "../user_events/user_events_selftests.h" /* share tracefs setup */ +#include "kselftest_harness.h" + +#define TRACEFS_ROOT "/sys/kernel/tracing" + +static int __tracefs_write(const char *path, const char *value) +{ + int fd, ret; + + fd = open(path, O_WRONLY | O_TRUNC); + if (fd < 0) + return fd; + + ret = write(fd, value, strlen(value)); + + close(fd); + + return ret == -1 ? -errno : 0; +} + +static int __tracefs_write_int(const char *path, int value) +{ + char *str; + int ret; + + if (asprintf(&str, "%d", value) < 0) + return -1; + + ret = __tracefs_write(path, str); + + free(str); + + return ret; +} + +#define tracefs_write_int(path, value) \ + ASSERT_EQ(__tracefs_write_int((path), (value)), 0) + +#define tracefs_write(path, value) \ + ASSERT_EQ(__tracefs_write((path), (value)), 0) + +static int tracefs_reset(void) +{ + if (__tracefs_write_int(TRACEFS_ROOT"/tracing_on", 0)) + return -1; + if (__tracefs_write(TRACEFS_ROOT"/trace", "")) + return -1; + if (__tracefs_write(TRACEFS_ROOT"/set_event", "")) + return -1; + if (__tracefs_write(TRACEFS_ROOT"/current_tracer", "nop")) + return -1; + + return 0; +} + +struct tracefs_cpu_map_desc { + struct trace_buffer_meta *meta; + int cpu_fd; +}; + +int tracefs_cpu_map(struct tracefs_cpu_map_desc *desc, int cpu) +{ + int page_size = getpagesize(); + char *cpu_path; + void *map; + + if (asprintf(&cpu_path, + TRACEFS_ROOT"/per_cpu/cpu%d/trace_pipe_raw", + cpu) < 0) + return -ENOMEM; + + desc->cpu_fd = open(cpu_path, O_RDONLY | O_NONBLOCK); + free(cpu_path); + if (desc->cpu_fd < 0) + return -ENODEV; + +again: + map = mmap(NULL, page_size, PROT_READ, MAP_SHARED, desc->cpu_fd, 0); + if (map == MAP_FAILED) + return -errno; + + desc->meta = (struct trace_buffer_meta *)map; + + /* the meta-page is bigger than the original mapping */ + if (page_size < desc->meta->meta_struct_len) { + int meta_page_size = desc->meta->meta_page_size; + + munmap(desc->meta, page_size); + page_size = meta_page_size; + goto again; + } + + return 0; +} + +void tracefs_cpu_unmap(struct tracefs_cpu_map_desc *desc) +{ + munmap(desc->meta, desc->meta->meta_page_size); + close(desc->cpu_fd); +} + +FIXTURE(map) { + struct tracefs_cpu_map_desc map_desc; + bool umount; +}; + +FIXTURE_VARIANT(map) { + int subbuf_size; +}; + +FIXTURE_VARIANT_ADD(map, subbuf_size_4k) { + .subbuf_size = 4, +}; + +FIXTURE_VARIANT_ADD(map, subbuf_size_8k) { + .subbuf_size = 8, +}; + +FIXTURE_SETUP(map) +{ + int cpu = sched_getcpu(); + cpu_set_t cpu_mask; + bool fail, umount; + char *message; + + if (getuid() != 0) + SKIP(return, "Skipping: %s", "Please run the test as root"); + + if (!tracefs_enabled(&message, &fail, &umount)) { + if (fail) { + TH_LOG("Tracefs setup failed: %s", message); + ASSERT_FALSE(fail); + } + SKIP(return, "Skipping: %s", message); + } + + self->umount = umount; + + ASSERT_GE(cpu, 0); + + ASSERT_EQ(tracefs_reset(), 0); + + tracefs_write_int(TRACEFS_ROOT"/buffer_subbuf_size_kb", variant->subbuf_size); + + ASSERT_EQ(tracefs_cpu_map(&self->map_desc, cpu), 0); + + /* + * Ensure generated events will be found on this very same ring-buffer. + */ + CPU_ZERO(&cpu_mask); + CPU_SET(cpu, &cpu_mask); + ASSERT_EQ(sched_setaffinity(0, sizeof(cpu_mask), &cpu_mask), 0); +} + +FIXTURE_TEARDOWN(map) +{ + tracefs_reset(); + + if (self->umount) + tracefs_unmount(); + + tracefs_cpu_unmap(&self->map_desc); +} + +TEST_F(map, meta_page_check) +{ + struct tracefs_cpu_map_desc *desc = &self->map_desc; + int cnt = 0; + + ASSERT_EQ(desc->meta->entries, 0); + ASSERT_EQ(desc->meta->overrun, 0); + ASSERT_EQ(desc->meta->read, 0); + + ASSERT_EQ(desc->meta->reader.id, 0); + ASSERT_EQ(desc->meta->reader.read, 0); + + ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0); + ASSERT_EQ(desc->meta->reader.id, 0); + + tracefs_write_int(TRACEFS_ROOT"/tracing_on", 1); + for (int i = 0; i < 16; i++) + tracefs_write_int(TRACEFS_ROOT"/trace_marker", i); +again: + ASSERT_EQ(ioctl(desc->cpu_fd, TRACE_MMAP_IOCTL_GET_READER), 0); + + ASSERT_EQ(desc->meta->entries, 16); + ASSERT_EQ(desc->meta->overrun, 0); + ASSERT_EQ(desc->meta->read, 16); + + ASSERT_EQ(desc->meta->reader.id, 1); + + if (!(cnt++)) + goto again; +} + +TEST_F(map, data_mmap) +{ + struct tracefs_cpu_map_desc *desc = &self->map_desc; + unsigned long meta_len, data_len; + void *data; + + meta_len = desc->meta->meta_page_size; + data_len = desc->meta->subbuf_size * desc->meta->nr_subbufs; + + /* Map all the available subbufs */ + data = mmap(NULL, data_len, PROT_READ, MAP_SHARED, + desc->cpu_fd, meta_len); + ASSERT_NE(data, MAP_FAILED); + munmap(data, data_len); + + /* Map all the available subbufs - 1 */ + data_len -= desc->meta->subbuf_size; + data = mmap(NULL, data_len, PROT_READ, MAP_SHARED, + desc->cpu_fd, meta_len); + ASSERT_NE(data, MAP_FAILED); + munmap(data, data_len); + + /* Offset within ring-buffer bounds, mapping size overflow */ + meta_len += desc->meta->subbuf_size * 2; + data = mmap(NULL, data_len, PROT_READ, MAP_SHARED, + desc->cpu_fd, meta_len); + ASSERT_EQ(data, MAP_FAILED); + + /* Offset outside ring-buffer bounds */ + data_len = desc->meta->subbuf_size * desc->meta->nr_subbufs; + data = mmap(NULL, data_len, PROT_READ, MAP_SHARED, + desc->cpu_fd, data_len + (desc->meta->subbuf_size * 2)); + ASSERT_EQ(data, MAP_FAILED); + + /* Verify meta-page padding */ + if (desc->meta->meta_page_size > getpagesize()) { + data_len = desc->meta->meta_page_size; + data = mmap(NULL, data_len, + PROT_READ, MAP_SHARED, desc->cpu_fd, 0); + ASSERT_NE(data, MAP_FAILED); + + for (int i = desc->meta->meta_struct_len; + i < desc->meta->meta_page_size; i += sizeof(int)) + ASSERT_EQ(*(int *)(data + i), 0); + + munmap(data, data_len); + } +} + +FIXTURE(snapshot) { + bool umount; +}; + +FIXTURE_SETUP(snapshot) +{ + bool fail, umount; + struct stat sb; + char *message; + + if (getuid() != 0) + SKIP(return, "Skipping: %s", "Please run the test as root"); + + if (stat(TRACEFS_ROOT"/snapshot", &sb)) + SKIP(return, "Skipping: %s", "snapshot not available"); + + if (!tracefs_enabled(&message, &fail, &umount)) { + if (fail) { + TH_LOG("Tracefs setup failed: %s", message); + ASSERT_FALSE(fail); + } + SKIP(return, "Skipping: %s", message); + } + + self->umount = umount; +} + +FIXTURE_TEARDOWN(snapshot) +{ + __tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger", + "!snapshot"); + tracefs_reset(); + + if (self->umount) + tracefs_unmount(); +} + +TEST_F(snapshot, excludes_map) +{ + struct tracefs_cpu_map_desc map_desc; + int cpu = sched_getcpu(); + + ASSERT_GE(cpu, 0); + tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger", + "snapshot"); + ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), -EBUSY); +} + +TEST_F(snapshot, excluded_by_map) +{ + struct tracefs_cpu_map_desc map_desc; + int cpu = sched_getcpu(); + + ASSERT_EQ(tracefs_cpu_map(&map_desc, cpu), 0); + + ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/events/sched/sched_switch/trigger", + "snapshot"), -EBUSY); + ASSERT_EQ(__tracefs_write(TRACEFS_ROOT"/snapshot", + "1"), -EBUSY); +} + +TEST_HARNESS_MAIN -- cgit v1.3.1