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Diffstat (limited to '')
| -rw-r--r-- | tools/testing/selftests/kvm/lib/userfaultfd_util.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/userfaultfd_util.c b/tools/testing/selftests/kvm/lib/userfaultfd_util.c new file mode 100644 index 000000000000..f4eef6eb2dc2 --- /dev/null +++ b/tools/testing/selftests/kvm/lib/userfaultfd_util.c @@ -0,0 +1,186 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KVM userfaultfd util + * Adapted from demand_paging_test.c + * + * Copyright (C) 2018, Red Hat, Inc. + * Copyright (C) 2019-2022 Google LLC + */ + +#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> + +#include "kvm_util.h" +#include "test_util.h" +#include "memstress.h" +#include "userfaultfd_util.h" + +#ifdef __NR_userfaultfd + +static void *uffd_handler_thread_fn(void *arg) +{ + struct uffd_desc *uffd_desc = (struct uffd_desc *)arg; + int uffd = uffd_desc->uffd; + int pipefd = uffd_desc->pipefds[0]; + useconds_t delay = uffd_desc->delay; + int64_t pages = 0; + struct timespec start; + struct timespec ts_diff; + + clock_gettime(CLOCK_MONOTONIC, &start); + while (1) { + struct uffd_msg msg; + struct pollfd pollfd[2]; + char tmp_chr; + int r; + + pollfd[0].fd = uffd; + pollfd[0].events = POLLIN; + pollfd[1].fd = pipefd; + pollfd[1].events = POLLIN; + + r = poll(pollfd, 2, -1); + switch (r) { + case -1: + pr_info("poll err"); + continue; + case 0: + continue; + case 1: + break; + default: + pr_info("Polling uffd returned %d", r); + return NULL; + } + + if (pollfd[0].revents & POLLERR) { + pr_info("uffd revents has POLLERR"); + return NULL; + } + + if (pollfd[1].revents & POLLIN) { + r = read(pollfd[1].fd, &tmp_chr, 1); + TEST_ASSERT(r == 1, + "Error reading pipefd in UFFD thread"); + break; + } + + if (!(pollfd[0].revents & POLLIN)) + continue; + + r = read(uffd, &msg, sizeof(msg)); + if (r == -1) { + if (errno == EAGAIN) + continue; + pr_info("Read of uffd got errno %d\n", errno); + return NULL; + } + + if (r != sizeof(msg)) { + pr_info("Read on uffd returned unexpected size: %d bytes", r); + return NULL; + } + + if (!(msg.event & UFFD_EVENT_PAGEFAULT)) + continue; + + if (delay) + usleep(delay); + r = uffd_desc->handler(uffd_desc->uffd_mode, uffd, &msg); + if (r < 0) + return NULL; + pages++; + } + + ts_diff = timespec_elapsed(start); + PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n", + pages, ts_diff.tv_sec, ts_diff.tv_nsec, + pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / NSEC_PER_SEC)); + + return NULL; +} + +struct uffd_desc *uffd_setup_demand_paging(int uffd_mode, useconds_t delay, + void *hva, uint64_t len, + uffd_handler_t handler) +{ + struct uffd_desc *uffd_desc; + bool is_minor = (uffd_mode == UFFDIO_REGISTER_MODE_MINOR); + int uffd; + struct uffdio_api uffdio_api; + struct uffdio_register uffdio_register; + uint64_t expected_ioctls = ((uint64_t) 1) << _UFFDIO_COPY; + int ret; + + PER_PAGE_DEBUG("Userfaultfd %s mode, faults resolved with %s\n", + is_minor ? "MINOR" : "MISSING", + is_minor ? "UFFDIO_CONINUE" : "UFFDIO_COPY"); + + uffd_desc = malloc(sizeof(struct uffd_desc)); + TEST_ASSERT(uffd_desc, "malloc failed"); + + /* In order to get minor faults, prefault via the alias. */ + if (is_minor) + expected_ioctls = ((uint64_t) 1) << _UFFDIO_CONTINUE; + + uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); + TEST_ASSERT(uffd >= 0, "uffd creation failed, errno: %d", errno); + + uffdio_api.api = UFFD_API; + uffdio_api.features = 0; + TEST_ASSERT(ioctl(uffd, UFFDIO_API, &uffdio_api) != -1, + "ioctl UFFDIO_API failed: %" PRIu64, + (uint64_t)uffdio_api.api); + + uffdio_register.range.start = (uint64_t)hva; + uffdio_register.range.len = len; + uffdio_register.mode = uffd_mode; + TEST_ASSERT(ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) != -1, + "ioctl UFFDIO_REGISTER failed"); + TEST_ASSERT((uffdio_register.ioctls & expected_ioctls) == + expected_ioctls, "missing userfaultfd ioctls"); + + ret = pipe2(uffd_desc->pipefds, O_CLOEXEC | O_NONBLOCK); + TEST_ASSERT(!ret, "Failed to set up pipefd"); + + uffd_desc->uffd_mode = uffd_mode; + uffd_desc->uffd = uffd; + uffd_desc->delay = delay; + uffd_desc->handler = handler; + pthread_create(&uffd_desc->thread, NULL, uffd_handler_thread_fn, + uffd_desc); + + PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n", + hva, hva + len); + + return uffd_desc; +} + +void uffd_stop_demand_paging(struct uffd_desc *uffd) +{ + char c = 0; + int ret; + + ret = write(uffd->pipefds[1], &c, 1); + TEST_ASSERT(ret == 1, "Unable to write to pipefd"); + + ret = pthread_join(uffd->thread, NULL); + TEST_ASSERT(ret == 0, "Pthread_join failed."); + + close(uffd->uffd); + + close(uffd->pipefds[1]); + close(uffd->pipefds[0]); + + free(uffd); +} + +#endif /* __NR_userfaultfd */ |