// SPDX-License-Identifier: GPL-2.0
/*
 * Test soft offline behavior for HugeTLB pages:
 * - if enable_soft_offline = 0, hugepages should stay intact and soft
 *   offlining failed with EOPNOTSUPP.
 * - if enable_soft_offline = 1, a hugepage should be dissolved and
 *   nr_hugepages/free_hugepages should be reduced by 1.
 *
 * Before running, make sure more than 2 hugepages of default_hugepagesz
 * are allocated. For example, if /proc/meminfo/Hugepagesize is 2048kB:
 *   echo 8 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
 */

#define _GNU_SOURCE
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <linux/magic.h>
#include <linux/memfd.h>
#include <sys/mman.h>
#include <sys/statfs.h>
#include <sys/types.h>

#include "kselftest.h"

#ifndef MADV_SOFT_OFFLINE
#define MADV_SOFT_OFFLINE 101
#endif

#define EPREFIX " !!! "

static int do_soft_offline(int fd, size_t len, int expect_errno)
{
        char *filemap = NULL;
        char *hwp_addr = NULL;
        const unsigned long pagesize = getpagesize();
        int ret = 0;

        if (ftruncate(fd, len) < 0) {
                ksft_perror(EPREFIX "ftruncate to len failed");
                return -1;
        }

        filemap = mmap(NULL, len, PROT_READ | PROT_WRITE,
                       MAP_SHARED | MAP_POPULATE, fd, 0);
        if (filemap == MAP_FAILED) {
                ksft_perror(EPREFIX "mmap failed");
                ret = -1;
                goto untruncate;
        }

        memset(filemap, 0xab, len);
        ksft_print_msg("Allocated %#lx bytes of hugetlb pages\n", len);

        hwp_addr = filemap + len / 2;
        ret = madvise(hwp_addr, pagesize, MADV_SOFT_OFFLINE);
        ksft_print_msg("MADV_SOFT_OFFLINE %p ret=%d, errno=%d\n",
                       hwp_addr, ret, errno);
        if (ret != 0)
                ksft_perror(EPREFIX "madvise failed");

        if (errno == expect_errno)
                ret = 0;
        else {
                ksft_print_msg("MADV_SOFT_OFFLINE should ret %d\n",
                               expect_errno);
                ret = -1;
        }

        munmap(filemap, len);
untruncate:
        if (ftruncate(fd, 0) < 0)
                ksft_perror(EPREFIX "ftruncate back to 0 failed");

        return ret;
}

static int set_enable_soft_offline(int value)
{
        char cmd[256] = {0};
        FILE *cmdfile = NULL;

        if (value != 0 && value != 1)
                return -EINVAL;

        sprintf(cmd, "echo %d > /proc/sys/vm/enable_soft_offline", value);
        cmdfile = popen(cmd, "r");

        if (cmdfile)
                ksft_print_msg("enable_soft_offline => %d\n", value);
        else {
                ksft_perror(EPREFIX "failed to set enable_soft_offline");
                return errno;
        }

        pclose(cmdfile);
        return 0;
}

static int read_nr_hugepages(unsigned long hugepage_size,
                             unsigned long *nr_hugepages)
{
        char buffer[256] = {0};
        char cmd[256] = {0};

        sprintf(cmd, "cat /sys/kernel/mm/hugepages/hugepages-%ldkB/nr_hugepages",
                hugepage_size);
        FILE *cmdfile = popen(cmd, "r");

        if (cmdfile == NULL) {
                ksft_perror(EPREFIX "failed to popen nr_hugepages");
                return -1;
        }

        if (!fgets(buffer, sizeof(buffer), cmdfile)) {
                ksft_perror(EPREFIX "failed to read nr_hugepages");
                pclose(cmdfile);
                return -1;
        }

        *nr_hugepages = atoll(buffer);
        pclose(cmdfile);
        return 0;
}

static int create_hugetlbfs_file(struct statfs *file_stat)
{
        int fd;

        fd = memfd_create("hugetlb_tmp", MFD_HUGETLB);
        if (fd < 0) {
                ksft_perror(EPREFIX "could not open hugetlbfs file");
                return -1;
        }

        memset(file_stat, 0, sizeof(*file_stat));
        if (fstatfs(fd, file_stat)) {
                ksft_perror(EPREFIX "fstatfs failed");
                goto close;
        }
        if (file_stat->f_type != HUGETLBFS_MAGIC) {
                ksft_print_msg(EPREFIX "not hugetlbfs file\n");
                goto close;
        }

        return fd;
close:
        close(fd);
        return -1;
}

static void test_soft_offline_common(int enable_soft_offline)
{
        int fd;
        int expect_errno = enable_soft_offline ? 0 : EOPNOTSUPP;
        struct statfs file_stat;
        unsigned long hugepagesize_kb = 0;
        unsigned long nr_hugepages_before = 0;
        unsigned long nr_hugepages_after = 0;
        int ret;

        ksft_print_msg("Test soft-offline when enabled_soft_offline=%d\n",
                       enable_soft_offline);

        fd = create_hugetlbfs_file(&file_stat);
        if (fd < 0)
                ksft_exit_fail_msg("Failed to create hugetlbfs file\n");

        hugepagesize_kb = file_stat.f_bsize / 1024;
        ksft_print_msg("Hugepagesize is %ldkB\n", hugepagesize_kb);

        if (set_enable_soft_offline(enable_soft_offline) != 0) {
                close(fd);
                ksft_exit_fail_msg("Failed to set enable_soft_offline\n");
        }

        if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_before) != 0) {
                close(fd);
                ksft_exit_fail_msg("Failed to read nr_hugepages\n");
        }

        ksft_print_msg("Before MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
                       nr_hugepages_before);

        ret = do_soft_offline(fd, 2 * file_stat.f_bsize, expect_errno);

        if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_after) != 0) {
                close(fd);
                ksft_exit_fail_msg("Failed to read nr_hugepages\n");
        }

        ksft_print_msg("After MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
                nr_hugepages_after);

        // No need for the hugetlbfs file from now on.
        close(fd);

        if (enable_soft_offline) {
                if (nr_hugepages_before != nr_hugepages_after + 1) {
                        ksft_test_result_fail("MADV_SOFT_OFFLINE should reduced 1 hugepage\n");
                        return;
                }
        } else {
                if (nr_hugepages_before != nr_hugepages_after) {
                        ksft_test_result_fail("MADV_SOFT_OFFLINE reduced %lu hugepages\n",
                                nr_hugepages_before - nr_hugepages_after);
                        return;
                }
        }

        ksft_test_result(ret == 0,
                         "Test soft-offline when enabled_soft_offline=%d\n",
                         enable_soft_offline);
}

int main(int argc, char **argv)
{
        ksft_print_header();
        ksft_set_plan(2);

        test_soft_offline_common(1);
        test_soft_offline_common(0);

        ksft_finished();
}