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@xxxxxxxxxx>
Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
---
.../selftests/kvm/include/kvm_util_base.h | 2 +
tools/testing/selftests/kvm/lib/kvm_util.c | 16 +++-
.../selftests/kvm/x86_64/nx_huge_pages_test.c | 75 +++++++++++++++----
.../kvm/x86_64/nx_huge_pages_test.sh | 39 ++++++----
4 files changed, 104 insertions(+), 28 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 1dac3c6607f1..8f6aad253392 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -414,4 +414,6 @@ 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 392abd3c323d..96faa14f4f32 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);
@@ -2756,3 +2761,12 @@ uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)
stat_name, ret);
return data;
}
+
+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 1c14368500b7..41b228b8cac3 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
@@ -13,6 +13,8 @@
#include <fcntl.h>
#include <stdint.h>
#include <time.h>
+#include <linux/reboot.h>
+#include <sys/syscall.h>
#include <test_util.h>
#include "kvm_util.h"
@@ -86,18 +88,45 @@ static void check_split_count(struct kvm_vm *vm, int expected_splits)
expected_splits, actual_splits);
}
-int main(int argc, char **argv)
+void run_test(bool disable_nx_huge_pages)
{
struct kvm_vm *vm;
struct timespec ts;
+ uint64_t pages;
void *hva;
-
- if (argc != 2 || strtol(argv[1], NULL, 0) != MAGIC_TOKEN) {
- printf("This test must be run through nx_huge_pages_test.sh");
- return KSFT_SKIP;
+ 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) {
+ kvm_check_cap(KVM_CAP_VM_DISABLE_NX_HUGE_PAGES);
+
+ /*
+ * Check if this process has the reboot permissions needed to
+ * disable NX huge pages on a VM.
+ *
+ * The reboot call below will never have any effect because
+ * the magic values are not set correctly, however the
+ * permission check is done before the magic value check.
+ */
+ r = syscall(SYS_reboot, 0, 0, 0, NULL);
+ if (r && errno == EPERM) {
+ r = vm_disable_nx_huge_pages(vm);
+ TEST_ASSERT(errno == EPERM,
+ "This process should not have permission to disable NX huge pages");
+ return;
+ }
+
+ TEST_ASSERT(r && errno == EINVAL,
+ "Reboot syscall should fail with -EINVAL");
+
+ r = vm_disable_nx_huge_pages(vm);
+ TEST_ASSERT(!r, "Disabling NX huge pages should succeed if process has reboot permissions");
}
- 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,
@@ -130,23 +159,27 @@ 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. The wrapper script sets
@@ -158,8 +191,11 @@ int main(int argc, char **argv)
/*
* 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);
/*
@@ -167,10 +203,21 @@ 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);
+}
+
+int main(int argc, char **argv)
+{
+ if (argc != 2 || strtol(argv[1], NULL, 0) != MAGIC_TOKEN) {
+ printf("This test must be run through nx_huge_pages_test.sh");
+ return KSFT_SKIP;
+ }
+
+ run_test(false);
+ run_test(true);
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 c2429ad8066a..b23993f3aab1 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
@@ -4,22 +4,35 @@
# tools/testing/selftests/kvm/nx_huge_page_test.sh
# Copyright (C) 2022, Google LLC.
-NX_HUGE_PAGES=$(cat /sys/module/kvm/parameters/nx_huge_pages)
-NX_HUGE_PAGES_RECOVERY_RATIO=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio)
-NX_HUGE_PAGES_RECOVERY_PERIOD=$(cat /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms)
-HUGE_PAGES=$(cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages)
+NX_HUGE_PAGES=$(sudo cat /sys/module/kvm/parameters/nx_huge_pages)
+NX_HUGE_PAGES_RECOVERY_RATIO=$(sudo cat /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio)
+NX_HUGE_PAGES_RECOVERY_PERIOD=$(sudo cat /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms)
+HUGE_PAGES=$(sudo cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages)
-echo 1 > /sys/module/kvm/parameters/nx_huge_pages
-echo 1 > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio
-echo 100 > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms
-echo 200 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
+sudo echo 1 > /sys/module/kvm/parameters/nx_huge_pages
+sudo echo 1 > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio
+sudo echo 100 > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms
+sudo echo 200 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
+
+NXECUTABLE="$(dirname $0)/nx_huge_pages_test"
+
+# Test with reboot permissions
+sudo setcap cap_sys_boot+ep $NXECUTABLE
+$NXECUTABLE 887563923
-"$(dirname $0)"/nx_huge_pages_test 887563923
RET=$?
-echo $NX_HUGE_PAGES > /sys/module/kvm/parameters/nx_huge_pages
-echo $NX_HUGE_PAGES_RECOVERY_RATIO > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio
-echo $NX_HUGE_PAGES_RECOVERY_PERIOD > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms
-echo $HUGE_PAGES > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
+if [ $RET -eq 0 ]; then
+ # Test without reboot permissions
+ sudo setcap cap_sys_boot-ep $NXECUTABLE
+ $NXECUTABLE 887563923
+
+ RET=$?
+fi
+
+sudo echo $NX_HUGE_PAGES > /sys/module/kvm/parameters/nx_huge_pages
+sudo echo $NX_HUGE_PAGES_RECOVERY_RATIO > /sys/module/kvm/parameters/nx_huge_pages_recovery_ratio
+sudo echo $NX_HUGE_PAGES_RECOVERY_PERIOD > /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms
+sudo echo $HUGE_PAGES > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
exit $RET
--
2.36.0.rc0.470.gd361397f0d-goog
