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// 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_reader_args *reader_args = (struct uffd_reader_args *)arg;
int uffd = reader_args->uffd;
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 = reader_args->pipe;
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 (reader_args->delay)
usleep(reader_args->delay);
r = reader_args->handler(reader_args->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,
uint64_t num_readers,
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, i;
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, "Failed to malloc uffd descriptor");
uffd_desc->pipefds = calloc(sizeof(int), num_readers);
TEST_ASSERT(uffd_desc->pipefds, "Failed to alloc pipes");
uffd_desc->readers = calloc(sizeof(pthread_t), num_readers);
TEST_ASSERT(uffd_desc->readers, "Failed to alloc reader threads");
uffd_desc->reader_args = calloc(sizeof(struct uffd_reader_args), num_readers);
TEST_ASSERT(uffd_desc->reader_args, "Failed to alloc reader_args");
uffd_desc->num_readers = num_readers;
/* 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");
uffd_desc->uffd = uffd;
for (i = 0; i < uffd_desc->num_readers; ++i) {
int pipes[2];
ret = pipe2((int *) &pipes, O_CLOEXEC | O_NONBLOCK);
TEST_ASSERT(!ret, "Failed to set up pipefd %i for uffd_desc %p",
i, uffd_desc);
uffd_desc->pipefds[i] = pipes[1];
uffd_desc->reader_args[i].uffd_mode = uffd_mode;
uffd_desc->reader_args[i].uffd = uffd;
uffd_desc->reader_args[i].delay = delay;
uffd_desc->reader_args[i].handler = handler;
uffd_desc->reader_args[i].pipe = pipes[0];
pthread_create(&uffd_desc->readers[i], NULL, uffd_handler_thread_fn,
&uffd_desc->reader_args[i]);
PER_VCPU_DEBUG("Created uffd thread %i for HVA range [%p, %p)\n",
i, hva, hva + len);
}
return uffd_desc;
}
void uffd_stop_demand_paging(struct uffd_desc *uffd)
{
char c = 0;
int i;
for (i = 0; i < uffd->num_readers; ++i)
TEST_ASSERT(write(uffd->pipefds[i], &c, 1) == 1,
"Unable to write to pipefd %i for uffd_desc %p", i, uffd);
for (i = 0; i < uffd->num_readers; ++i)
TEST_ASSERT(!pthread_join(uffd->readers[i], NULL),
"Pthread_join failed on reader %i for uffd_desc %p", i, uffd);
close(uffd->uffd);
for (i = 0; i < uffd->num_readers; ++i) {
close(uffd->pipefds[i]);
close(uffd->reader_args[i].pipe);
}
free(uffd->pipefds);
free(uffd->readers);
free(uffd->reader_args);
free(uffd);
}
#endif /* __NR_userfaultfd */
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