From patchwork Mon Oct 17 19:58:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ricardo Koller X-Patchwork-Id: 13009398 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE4E0C433FE for ; Mon, 17 Oct 2022 19:58:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230260AbiJQT6n (ORCPT ); Mon, 17 Oct 2022 15:58:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230004AbiJQT6l (ORCPT ); Mon, 17 Oct 2022 15:58:41 -0400 Received: from mail-pg1-x549.google.com (mail-pg1-x549.google.com [IPv6:2607:f8b0:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8184733DA for ; Mon, 17 Oct 2022 12:58:39 -0700 (PDT) Received: by mail-pg1-x549.google.com with SMTP id h19-20020a63e153000000b00434dfee8dbaso6934761pgk.18 for ; Mon, 17 Oct 2022 12:58:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=P0k63Fd1xYq4jGAXfZxTZxY+rWkD14DilQ3pe5s+Qpo=; b=dQUTXsRzAVjtUvzYey6a2PMbBrV2ZYYO6nFkkImEv/raFfCHLfSuZaicy7+/MMfHFq qZpwPsNwucSz9jXUW0hDjHSeHsEVceIZO6G1cVmWaa/D2MHck3onIipgpXDjjUr3211n QMkFw89LMeF3QzBJ2Dpj3/lLlbv5MY8ZyleVt7HyCQGVYdrCa9pJ4z2yOCogjwrSh0DI 5JvYYxq/p96o6sucBty+ssIiX1f8N+IsEyLofh1dc4mxhnBsgz4+jcBYplFoinEERidA J2RozelPa7VGhJy2Lal8UMUvw8Rp71xmiMZg9djsM+lGLPD4ikgaN0biMxeMVwxEi3Cb JA6Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=P0k63Fd1xYq4jGAXfZxTZxY+rWkD14DilQ3pe5s+Qpo=; b=2QTzW9+9NtzHK3FJ4rci+oJe719s9gqqyLQiGlPAnrDygDgXDmP5P58UfIPnnLMbQ/ yzpF3BUEpIbv799I22RMZHCaaM/MgEt1qQJlkivCyHcd9Igcy4gsuY4OVxKBstQ1ou4g BXZ0gUUipRUGsvFzsEWy0brOCjnSABGK2xDayvm/XU9ufoROb6MUAWh+QChxpzLr8YHh eyfHLtdHuthKk3CNB9C3IrNHMQXAt+saKvG2+U83MR5/U0QI96GxHfG/Imqtee4VmCMi Hr+uRA/uhmZWjhhJwnrUZztRv7J+GrkKdzd0zGUE3mTT9NnlWrLQskz4okiRtGsQdVyd 2WeA== X-Gm-Message-State: ACrzQf0Wx4XiASRnjfKD21+qYtuPbZpmXFoHFtwleNC0qrFNSZ7TQaSJ i/hiEGpU3QqJmHSPcU8dXTotXu7Tvd0NczVYUe/F+9uFMtCxMFAWgRKqUSpkK460Bl6Rs6SuN72 eN3wZ9j9CXtLy1ts/BjMHl8mNclDxY9od+OUN6Bgg+153KgMgNP/aDi0ltY2kXkc= X-Google-Smtp-Source: AMsMyM6RR5MdRZJA19EidqeLSiBpxMXXxL89SG6/SxjHM8yzdoHUiRBO9HyvnAVztOKAbsiq1o67FyNP0XECIQ== X-Received: from ricarkol4.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1248]) (user=ricarkol job=sendgmr) by 2002:a17:90a:4811:b0:20a:fee1:8f69 with SMTP id a17-20020a17090a481100b0020afee18f69mr1479651pjh.0.1666036718716; Mon, 17 Oct 2022 12:58:38 -0700 (PDT) Date: Mon, 17 Oct 2022 19:58:21 +0000 In-Reply-To: <20221017195834.2295901-1-ricarkol@google.com> Mime-Version: 1.0 References: <20221017195834.2295901-1-ricarkol@google.com> X-Mailer: git-send-email 2.38.0.413.g74048e4d9e-goog Message-ID: <20221017195834.2295901-2-ricarkol@google.com> Subject: [PATCH v10 01/14] KVM: selftests: Add a userfaultfd library From: Ricardo Koller To: kvm@vger.kernel.org, kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu, andrew.jones@linux.dev Cc: pbonzini@redhat.com, maz@kernel.org, seanjc@google.com, alexandru.elisei@arm.com, eric.auger@redhat.com, oupton@google.com, reijiw@google.com, rananta@google.com, bgardon@google.com, dmatlack@google.com, axelrasmussen@google.com, Ricardo Koller , Oliver Upton Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Move the generic userfaultfd code out of demand_paging_test.c into a common library, userfaultfd_util. This library consists of a setup and a stop function. The setup function starts a thread for handling page faults using the handler callback function. This setup returns a uffd_desc object which is then used in the stop function (to wait and destroy the threads). Reviewed-by: Oliver Upton Reviewed-by: Ben Gardon Signed-off-by: Ricardo Koller --- tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/demand_paging_test.c | 228 +++--------------- .../selftests/kvm/include/userfaultfd_util.h | 45 ++++ .../selftests/kvm/lib/userfaultfd_util.c | 186 ++++++++++++++ 4 files changed, 262 insertions(+), 198 deletions(-) create mode 100644 tools/testing/selftests/kvm/include/userfaultfd_util.h create mode 100644 tools/testing/selftests/kvm/lib/userfaultfd_util.c diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 0172eb6cb6ee..08a2606aff33 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -47,6 +47,7 @@ LIBKVM += lib/perf_test_util.c LIBKVM += lib/rbtree.c LIBKVM += lib/sparsebit.c LIBKVM += lib/test_util.c +LIBKVM += lib/userfaultfd_util.c LIBKVM_STRING += lib/string_override.c diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c index 779ae54f89c4..8e1fe4ffcccd 100644 --- a/tools/testing/selftests/kvm/demand_paging_test.c +++ b/tools/testing/selftests/kvm/demand_paging_test.c @@ -22,23 +22,13 @@ #include "test_util.h" #include "perf_test_util.h" #include "guest_modes.h" +#include "userfaultfd_util.h" #ifdef __NR_userfaultfd -#ifdef PRINT_PER_PAGE_UPDATES -#define PER_PAGE_DEBUG(...) printf(__VA_ARGS__) -#else -#define PER_PAGE_DEBUG(...) _no_printf(__VA_ARGS__) -#endif - -#ifdef PRINT_PER_VCPU_UPDATES -#define PER_VCPU_DEBUG(...) printf(__VA_ARGS__) -#else -#define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__) -#endif - static int nr_vcpus = 1; static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE; + static size_t demand_paging_size; static char *guest_data_prototype; @@ -67,9 +57,11 @@ static void vcpu_worker(struct perf_test_vcpu_args *vcpu_args) ts_diff.tv_sec, ts_diff.tv_nsec); } -static int handle_uffd_page_request(int uffd_mode, int uffd, uint64_t addr) +static int handle_uffd_page_request(int uffd_mode, int uffd, + struct uffd_msg *msg) { pid_t tid = syscall(__NR_gettid); + uint64_t addr = msg->arg.pagefault.address; struct timespec start; struct timespec ts_diff; int r; @@ -116,174 +108,32 @@ static int handle_uffd_page_request(int uffd_mode, int uffd, uint64_t addr) return 0; } -bool quit_uffd_thread; - -struct uffd_handler_args { +struct test_params { int uffd_mode; - int uffd; - int pipefd; - useconds_t delay; + useconds_t uffd_delay; + enum vm_mem_backing_src_type src_type; + bool partition_vcpu_memory_access; }; -static void *uffd_handler_thread_fn(void *arg) -{ - struct uffd_handler_args *uffd_args = (struct uffd_handler_args *)arg; - int uffd = uffd_args->uffd; - int pipefd = uffd_args->pipefd; - useconds_t delay = uffd_args->delay; - int64_t pages = 0; - struct timespec start; - struct timespec ts_diff; - - clock_gettime(CLOCK_MONOTONIC, &start); - while (!quit_uffd_thread) { - struct uffd_msg msg; - struct pollfd pollfd[2]; - char tmp_chr; - int r; - uint64_t addr; - - 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\n"); - return NULL; - } - - 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); - addr = msg.arg.pagefault.address; - r = handle_uffd_page_request(uffd_args->uffd_mode, uffd, addr); - 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 / 100000000.0)); - - return NULL; -} - -static void setup_demand_paging(struct kvm_vm *vm, - pthread_t *uffd_handler_thread, int pipefd, - int uffd_mode, useconds_t uffd_delay, - struct uffd_handler_args *uffd_args, - void *hva, void *alias, uint64_t len) +static void prefault_mem(void *alias, uint64_t len) { - 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; + size_t p; - PER_PAGE_DEBUG("Userfaultfd %s mode, faults resolved with %s\n", - is_minor ? "MINOR" : "MISSING", - is_minor ? "UFFDIO_CONINUE" : "UFFDIO_COPY"); - - /* In order to get minor faults, prefault via the alias. */ - if (is_minor) { - size_t p; - - expected_ioctls = ((uint64_t) 1) << _UFFDIO_CONTINUE; - - TEST_ASSERT(alias != NULL, "Alias required for minor faults"); - for (p = 0; p < (len / demand_paging_size); ++p) { - memcpy(alias + (p * demand_paging_size), - guest_data_prototype, demand_paging_size); - } + TEST_ASSERT(alias != NULL, "Alias required for minor faults"); + for (p = 0; p < (len / demand_paging_size); ++p) { + memcpy(alias + (p * demand_paging_size), + guest_data_prototype, demand_paging_size); } - - uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); - TEST_ASSERT(uffd >= 0, __KVM_SYSCALL_ERROR("userfaultfd()", uffd)); - - uffdio_api.api = UFFD_API; - uffdio_api.features = 0; - ret = ioctl(uffd, UFFDIO_API, &uffdio_api); - TEST_ASSERT(ret != -1, __KVM_SYSCALL_ERROR("UFFDIO_API", ret)); - - uffdio_register.range.start = (uint64_t)hva; - uffdio_register.range.len = len; - uffdio_register.mode = uffd_mode; - ret = ioctl(uffd, UFFDIO_REGISTER, &uffdio_register); - TEST_ASSERT(ret != -1, __KVM_SYSCALL_ERROR("UFFDIO_REGISTER", ret)); - TEST_ASSERT((uffdio_register.ioctls & expected_ioctls) == - expected_ioctls, "missing userfaultfd ioctls"); - - uffd_args->uffd_mode = uffd_mode; - uffd_args->uffd = uffd; - uffd_args->pipefd = pipefd; - uffd_args->delay = uffd_delay; - pthread_create(uffd_handler_thread, NULL, uffd_handler_thread_fn, - uffd_args); - - PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n", - hva, hva + len); } -struct test_params { - int uffd_mode; - useconds_t uffd_delay; - enum vm_mem_backing_src_type src_type; - bool partition_vcpu_memory_access; -}; - static void run_test(enum vm_guest_mode mode, void *arg) { struct test_params *p = arg; - pthread_t *uffd_handler_threads = NULL; - struct uffd_handler_args *uffd_args = NULL; + struct uffd_desc **uffd_descs = NULL; struct timespec start; struct timespec ts_diff; - int *pipefds = NULL; struct kvm_vm *vm; - int r, i; + int i; vm = perf_test_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1, p->src_type, p->partition_vcpu_memory_access); @@ -296,15 +146,8 @@ static void run_test(enum vm_guest_mode mode, void *arg) memset(guest_data_prototype, 0xAB, demand_paging_size); if (p->uffd_mode) { - uffd_handler_threads = - malloc(nr_vcpus * sizeof(*uffd_handler_threads)); - TEST_ASSERT(uffd_handler_threads, "Memory allocation failed"); - - uffd_args = malloc(nr_vcpus * sizeof(*uffd_args)); - TEST_ASSERT(uffd_args, "Memory allocation failed"); - - pipefds = malloc(sizeof(int) * nr_vcpus * 2); - TEST_ASSERT(pipefds, "Unable to allocate memory for pipefd"); + uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *)); + TEST_ASSERT(uffd_descs, "Memory allocation failed"); for (i = 0; i < nr_vcpus; i++) { struct perf_test_vcpu_args *vcpu_args; @@ -317,19 +160,17 @@ static void run_test(enum vm_guest_mode mode, void *arg) vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa); vcpu_alias = addr_gpa2alias(vm, vcpu_args->gpa); + prefault_mem(vcpu_alias, + vcpu_args->pages * perf_test_args.guest_page_size); + /* * Set up user fault fd to handle demand paging * requests. */ - r = pipe2(&pipefds[i * 2], - O_CLOEXEC | O_NONBLOCK); - TEST_ASSERT(!r, "Failed to set up pipefd"); - - setup_demand_paging(vm, &uffd_handler_threads[i], - pipefds[i * 2], p->uffd_mode, - p->uffd_delay, &uffd_args[i], - vcpu_hva, vcpu_alias, - vcpu_args->pages * perf_test_args.guest_page_size); + uffd_descs[i] = uffd_setup_demand_paging( + p->uffd_mode, p->uffd_delay, vcpu_hva, + vcpu_args->pages * perf_test_args.guest_page_size, + &handle_uffd_page_request); } } @@ -344,15 +185,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) pr_info("All vCPU threads joined\n"); if (p->uffd_mode) { - char c; - /* Tell the user fault fd handler threads to quit */ - for (i = 0; i < nr_vcpus; i++) { - r = write(pipefds[i * 2 + 1], &c, 1); - TEST_ASSERT(r == 1, "Unable to write to pipefd"); - - pthread_join(uffd_handler_threads[i], NULL); - } + for (i = 0; i < nr_vcpus; i++) + uffd_stop_demand_paging(uffd_descs[i]); } pr_info("Total guest execution time: %ld.%.9lds\n", @@ -364,11 +199,8 @@ static void run_test(enum vm_guest_mode mode, void *arg) perf_test_destroy_vm(vm); free(guest_data_prototype); - if (p->uffd_mode) { - free(uffd_handler_threads); - free(uffd_args); - free(pipefds); - } + if (p->uffd_mode) + free(uffd_descs); } static void help(char *name) diff --git a/tools/testing/selftests/kvm/include/userfaultfd_util.h b/tools/testing/selftests/kvm/include/userfaultfd_util.h new file mode 100644 index 000000000000..877449c34592 --- /dev/null +++ b/tools/testing/selftests/kvm/include/userfaultfd_util.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * KVM userfaultfd util + * + * Copyright (C) 2018, Red Hat, Inc. + * Copyright (C) 2019-2022 Google LLC + */ + +#define _GNU_SOURCE /* for pipe2 */ + +#include +#include +#include +#include + +#include "test_util.h" + +typedef int (*uffd_handler_t)(int uffd_mode, int uffd, struct uffd_msg *msg); + +struct uffd_desc { + int uffd_mode; + int uffd; + int pipefds[2]; + useconds_t delay; + uffd_handler_t handler; + pthread_t thread; +}; + +struct uffd_desc *uffd_setup_demand_paging(int uffd_mode, useconds_t delay, + void *hva, uint64_t len, + uffd_handler_t handler); + +void uffd_stop_demand_paging(struct uffd_desc *uffd); + +#ifdef PRINT_PER_PAGE_UPDATES +#define PER_PAGE_DEBUG(...) printf(__VA_ARGS__) +#else +#define PER_PAGE_DEBUG(...) _no_printf(__VA_ARGS__) +#endif + +#ifdef PRINT_PER_VCPU_UPDATES +#define PER_VCPU_DEBUG(...) printf(__VA_ARGS__) +#else +#define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__) +#endif 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..3b44846fc277 --- /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 +#include +#include +#include +#include +#include +#include +#include + +#include "kvm_util.h" +#include "test_util.h" +#include "perf_test_util.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\n"); + return NULL; + } + + 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 / 100000000.0)); + + 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 */