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    Subject[PATCH v8 10/11] KVM: selftests: Test disabling NX hugepages on a VM
    From
    Add an argument to the NX huge pages test to test disabling the feature
    on a VM using the new capability.

    Reviewed-by: David Matlack <dmatlack@google.com>
    Signed-off-by: Ben Gardon <bgardon@google.com>
    ---
    .../selftests/kvm/include/kvm_util_base.h | 2 +
    tools/testing/selftests/kvm/lib/kvm_util.c | 27 +++-
    .../selftests/kvm/x86_64/nx_huge_pages_test.c | 140 ++++++++++++------
    .../kvm/x86_64/nx_huge_pages_test.sh | 14 +-
    4 files changed, 133 insertions(+), 50 deletions(-)

    diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
    index 3c9898c59ea1..6aa06a312250 100644
    --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
    +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
    @@ -447,4 +447,6 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)

    uint32_t guest_get_vcpuid(void);

    +int __vm_disable_nx_huge_pages(struct kvm_vm *vm);
    +
    #endif /* SELFTEST_KVM_UTIL_BASE_H */
    diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
    index 385f249c2dc5..33d4d64c1391 100644
    --- a/tools/testing/selftests/kvm/lib/kvm_util.c
    +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
    @@ -112,6 +112,11 @@ int vm_check_cap(struct kvm_vm *vm, long cap)
    return ret;
    }

    +static int __vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap)
    +{
    + return ioctl(vm->fd, KVM_ENABLE_CAP, cap);
    +}
    +
    /* VM Enable Capability
    *
    * Input Args:
    @@ -128,7 +133,7 @@ int vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap)
    {
    int ret;

    - ret = ioctl(vm->fd, KVM_ENABLE_CAP, cap);
    + ret = __vm_enable_cap(vm, cap);
    TEST_ASSERT(ret == 0, "KVM_ENABLE_CAP IOCTL failed,\n"
    " rc: %i errno: %i", ret, errno);

    @@ -2718,3 +2723,23 @@ void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
    free(stats_desc);
    close(stats_fd);
    }
    +
    +/* VM disable NX huge pages
    + *
    + * Input Args:
    + * vm - Virtual Machine
    + *
    + * Output Args: None
    + *
    + * Return: On success, 0. -ERRNO on failure.
    + *
    + * Disables NX huge pages for the VM.
    + */
    +int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
    +{
    + struct kvm_enable_cap cap = { 0 };
    +
    + cap.cap = KVM_CAP_VM_DISABLE_NX_HUGE_PAGES;
    + cap.args[0] = 0;
    + return __vm_enable_cap(vm, &cap);
    +}
    diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
    index 09e05cda3dcd..9ff554a572c0 100644
    --- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
    +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
    @@ -107,52 +107,37 @@ static void wait_for_reclaim(int reclaim_period_ms)
    nanosleep(&ts, NULL);
    }

    -static void help(char *name)
    -{
    - puts("");
    - printf("usage: %s [-h] [-p period_ms] [-t token]\n", name);
    - puts("");
    - printf(" -p: The NX reclaim period in miliseconds.\n");
    - printf(" -t: The magic token to indicate environment setup is done.\n");
    - puts("");
    - exit(0);
    -}
    -
    -int main(int argc, char **argv)
    +void run_test(int reclaim_period_ms, bool disable_nx_huge_pages,
    + bool reboot_permissions)
    {
    - int reclaim_period_ms = 0, token = 0, opt;
    struct kvm_vm *vm;
    + uint64_t pages;
    void *hva;
    -
    - while ((opt = getopt(argc, argv, "hp:t:")) != -1) {
    - switch (opt) {
    - case 'p':
    - reclaim_period_ms = atoi(optarg);
    - break;
    - case 't':
    - token = atoi(optarg);
    - break;
    - case 'h':
    - default:
    - help(argv[0]);
    - break;
    + int r;
    +
    + pages = vm_pages_needed(VM_MODE_DEFAULT, 1, DEFAULT_GUEST_PHY_PAGES,
    + 0, 0);
    + vm = vm_create_without_vcpus(VM_MODE_DEFAULT, pages);
    +
    + if (disable_nx_huge_pages) {
    + /*
    + * Cannot run the test without NX huge pages if the kernel
    + * does not support it.
    + */
    + if (!kvm_check_cap(KVM_CAP_VM_DISABLE_NX_HUGE_PAGES))
    + return;
    +
    + r = __vm_disable_nx_huge_pages(vm);
    + if (reboot_permissions) {
    + TEST_ASSERT(!r, "Disabling NX huge pages should succeed if process has reboot permissions");
    + } else {
    + TEST_ASSERT(r == -1 && errno == EPERM,
    + "This process should not have permission to disable NX huge pages");
    + return;
    }
    }

    - if (token != MAGIC_TOKEN) {
    - print_skip("This test must be run with the magic token %d.\n"
    - "This is done by nx_huge_pages_test.sh, which\n"
    - "also handles environment setup for the test.",
    - MAGIC_TOKEN);
    - exit(KSFT_SKIP);
    - }
    -
    - if (!reclaim_period_ms) {
    - print_skip("The NX reclaim period must be specified and non-zero");
    - exit(KSFT_SKIP);
    - }
    -
    - vm = vm_create_default(0, 0, guest_code);
    + vm_vcpu_add_default(vm, 0, guest_code);

    vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_HUGETLB,
    HPAGE_GPA, HPAGE_SLOT,
    @@ -185,31 +170,38 @@ int main(int argc, char **argv)
    /*
    * Next, the guest will execute from the first huge page, causing it
    * to be remapped at 4k.
    + *
    + * If NX huge pages are disabled, this should have no effect.
    */
    vcpu_run(vm, 0);
    - check_2m_page_count(vm, 1);
    - check_split_count(vm, 1);
    + check_2m_page_count(vm, disable_nx_huge_pages ? 2 : 1);
    + check_split_count(vm, disable_nx_huge_pages ? 0 : 1);

    /*
    * Executing from the third huge page (previously unaccessed) will
    * cause part to be mapped at 4k.
    + *
    + * If NX huge pages are disabled, it should be mapped at 2M.
    */
    vcpu_run(vm, 0);
    - check_2m_page_count(vm, 1);
    - check_split_count(vm, 2);
    + check_2m_page_count(vm, disable_nx_huge_pages ? 3 : 1);
    + check_split_count(vm, disable_nx_huge_pages ? 0 : 2);

    /* Reading from the first huge page again should have no effect. */
    vcpu_run(vm, 0);
    - check_2m_page_count(vm, 1);
    - check_split_count(vm, 2);
    + check_2m_page_count(vm, disable_nx_huge_pages ? 3 : 1);
    + check_split_count(vm, disable_nx_huge_pages ? 0 : 2);

    /* Give recovery thread time to run. */
    wait_for_reclaim(reclaim_period_ms);

    /*
    * Now that the reclaimer has run, all the split pages should be gone.
    + *
    + * If NX huge pages are disabled, the relaimer will not run, so
    + * nothing should change from here on.
    */
    - check_2m_page_count(vm, 1);
    + check_2m_page_count(vm, disable_nx_huge_pages ? 3 : 1);
    check_split_count(vm, 0);

    /*
    @@ -217,10 +209,62 @@ int main(int argc, char **argv)
    * reading from it causes a huge page mapping to be installed.
    */
    vcpu_run(vm, 0);
    - check_2m_page_count(vm, 2);
    + check_2m_page_count(vm, disable_nx_huge_pages ? 3 : 2);
    check_split_count(vm, 0);

    kvm_vm_free(vm);
    +}
    +
    +static void help(char *name)
    +{
    + puts("");
    + printf("usage: %s [-h] [-p period_ms] [-t token]\n", name);
    + puts("");
    + printf(" -p: The NX reclaim period in miliseconds.\n");
    + printf(" -t: The magic token to indicate environment setup is done.\n");
    + printf(" -r: The test has reboot permissions and can disable NX huge pages.\n");
    + puts("");
    + exit(0);
    +}
    +
    +int main(int argc, char **argv)
    +{
    + int reclaim_period_ms = 0, token = 0, opt;
    + bool reboot_permissions = false;
    +
    + while ((opt = getopt(argc, argv, "hp:t:r")) != -1) {
    + switch (opt) {
    + case 'p':
    + reclaim_period_ms = atoi(optarg);
    + break;
    + case 't':
    + token = atoi(optarg);
    + break;
    + case 'r':
    + reboot_permissions = true;
    + break;
    + case 'h':
    + default:
    + help(argv[0]);
    + break;
    + }
    + }
    +
    + if (token != MAGIC_TOKEN) {
    + print_skip("This test must be run with the magic token %d.\n"
    + "This is done by nx_huge_pages_test.sh, which\n"
    + "also handles environment setup for the test.",
    + MAGIC_TOKEN);
    + exit(KSFT_SKIP);
    + }
    +
    + if (!reclaim_period_ms) {
    + print_skip("The NX reclaim period must be specified and non-zero");
    + exit(KSFT_SKIP);
    + }
    +
    + run_test(reclaim_period_ms, false, reboot_permissions);
    + run_test(reclaim_period_ms, true, reboot_permissions);

    return 0;
    }
    diff --git a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
    index 4e090a84f5f3..6bd8e026ee61 100755
    --- a/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
    +++ b/tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
    @@ -20,6 +20,8 @@ function sudo_echo () {
    echo "$1" | sudo tee -a "$2" > /dev/null
    }

    +NXECUTABLE="$(dirname $0)/nx_huge_pages_test"
    +
    (
    set -e

    @@ -28,7 +30,17 @@ function sudo_echo () {
    sudo_echo 100 /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms
    sudo_echo "$(( $HUGE_PAGES + 3 ))" /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

    - "$(dirname $0)"/nx_huge_pages_test -t 887563923 -p 100
    + # Test with reboot permissions
    + if [ $(whoami) != "root" ] ; then
    + sudo setcap cap_sys_boot+ep $NXECUTABLE
    + fi
    + $NXECUTABLE -t 887563923 -p 100 -r
    +
    + # Test without reboot permissions
    + if [ $(whoami) != "root" ] ; then
    + sudo setcap cap_sys_boot-ep $NXECUTABLE
    + $NXECUTABLE -t 887563923 -p 100
    + fi
    )
    RET=$?

    --
    2.36.1.124.g0e6072fb45-goog
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