On Wed, Mar 23, 2022 at 3:54 PM Ricardo Koller <ricarkol@xxxxxxxxxx> wrote:
>
> 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).
>
> Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
Fantastic refactor, thank you for doing this.
Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/Makefile | 2 +-
> .../selftests/kvm/demand_paging_test.c | 227 +++---------------
> .../selftests/kvm/include/userfaultfd_util.h | 47 ++++
> .../selftests/kvm/lib/userfaultfd_util.c | 187 +++++++++++++++
> 4 files changed, 264 insertions(+), 199 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 0e4926bc9a58..bc5f89b3700e 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -37,7 +37,7 @@ ifeq ($(ARCH),riscv)
> UNAME_M := riscv
> endif
>
> -LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c
> +LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c lib/userfaultfd_util.c
> LIBKVM_x86_64 = lib/x86_64/apic.c lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
> LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S lib/aarch64/spinlock.c lib/aarch64/gic.c lib/aarch64/gic_v3.c lib/aarch64/vgic.c
> LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 6a719d065599..b3d457cecd68 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;
>
> @@ -69,9 +59,11 @@ 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;
> @@ -118,175 +110,32 @@ 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)
> +static void prefault_mem(void *alias, uint64_t len)
> {
> - 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;
> + size_t p;
>
> - 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++;
> + 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);
> }
> -
> - 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)
> -{
> - 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;
> -
> - 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);
> - }
> - }
> -
> - 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");
> -
> - 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 vcpu_id;
> - int r;
>
> vm = perf_test_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
> p->src_type, p->partition_vcpu_memory_access);
> @@ -299,15 +148,8 @@ 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 (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> struct perf_test_vcpu_args *vcpu_args;
> @@ -320,19 +162,17 @@ 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[vcpu_id * 2],
> - O_CLOEXEC | O_NONBLOCK);
> - TEST_ASSERT(!r, "Failed to set up pipefd");
> -
> - setup_demand_paging(vm, &uffd_handler_threads[vcpu_id],
> - pipefds[vcpu_id * 2], p->uffd_mode,
> - p->uffd_delay, &uffd_args[vcpu_id],
> - vcpu_hva, vcpu_alias,
> - vcpu_args->pages * perf_test_args.guest_page_size);
> + uffd_descs[vcpu_id] = 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);
> }
> }
>
> @@ -347,15 +187,9 @@ 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 (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
> - r = write(pipefds[vcpu_id * 2 + 1], &c, 1);
> - TEST_ASSERT(r == 1, "Unable to write to pipefd");
> -
> - pthread_join(uffd_handler_threads[vcpu_id], NULL);
> - }
> + for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++)
> + uffd_stop_demand_paging(uffd_descs[vcpu_id]);
> }
>
> pr_info("Total guest execution time: %ld.%.9lds\n",
> @@ -367,11 +201,8 @@ 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..dffb4e768d56
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/userfaultfd_util.h
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KVM userfaultfd util
> + * Adapted from demand_paging_test.c
> + *
> + * Copyright (C) 2018, Red Hat, Inc.
> + * Copyright (C) 2019, Google, Inc.
> + * Copyright (C) 2022, Google, Inc.
> + */
> +
> +#define _GNU_SOURCE /* for pipe2 */
> +
> +#include <inttypes.h>
> +#include <time.h>
> +#include <pthread.h>
> +#include <linux/userfaultfd.h>
> +
> +#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 uffd_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..4395032ccbe4
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/userfaultfd_util.c
> @@ -0,0 +1,187 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * KVM userfaultfd util
> + * Adapted from demand_paging_test.c
> + *
> + * Copyright (C) 2018, Red Hat, Inc.
> + * Copyright (C) 2019, Google, Inc.
> + * Copyright (C) 2022, 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>
> +
> +#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 uffd_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 = uffd_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 */
> --
> 2.35.1.894.gb6a874cedc-goog
>
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