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KVM: selftests: Test disabling NX hugepages on a VM

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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>
Message-Id: <20220613212523.3436117-10-bgardon@google.com>
[Handle failure of sudo or setcap more gracefully. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ben Gardon 2022-06-13 21:25:22 +00:00 committed by Paolo Bonzini
parent 8448ec5993
commit b774da3f2e
3 changed files with 113 additions and 48 deletions
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6
tools/testing/selftests/kvm/include/kvm_util_base.h
View File

@ -809,4 +809,10 @@ static inline void virt_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
virt_arch_dump(stream, vm, indent);
}
static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
{
return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
}
#endif /* SELFTEST_KVM_UTIL_BASE_H */

134
tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.c
View File

@ -107,53 +107,34 @@ static void wait_for_reclaim(int reclaim_period_ms)
nanosleep(&ts, NULL);
}
static void help(char *name)
void run_test(int reclaim_period_ms, bool disable_nx_huge_pages,
bool reboot_permissions)
{
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)
{
int reclaim_period_ms = 0, token = 0, opt;
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
void *hva;
int r;
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;
vm = vm_create(1);
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(1);
vcpu = vm_vcpu_add(vm, 0, guest_code);
vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_HUGETLB,
@ -187,31 +168,38 @@ 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(vcpu);
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(vcpu);
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(vcpu);
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);
/*
@ -219,10 +207,62 @@ int main(int argc, char **argv)
* reading from it causes a huge page mapping to be installed.
*/
vcpu_run(vcpu);
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;
}

21
tools/testing/selftests/kvm/x86_64/nx_huge_pages_test.sh
View File

@ -20,6 +20,10 @@ function sudo_echo () {
echo "$1" | sudo tee -a "$2" > /dev/null
}
NXECUTABLE="$(dirname $0)/nx_huge_pages_test"
sudo_echo test /dev/null || exit 4 # KSFT_SKIP=4
(
set -e
@ -28,7 +32,22 @@ function sudo_echo () {
sudo_echo 100 /sys/module/kvm/parameters/nx_huge_pages_recovery_period_ms
sudo_echo "$(( $HUGE_PAGES + 3 ))" /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
"$(dirname $0)"/nx_huge_pages_test -t 887563923 -p 100
# Test with reboot permissions
if [ $(whoami) == "root" ] || sudo setcap cap_sys_boot+ep $NXECUTABLE 2> /dev/null; then
echo Running test with CAP_SYS_BOOT enabled
$NXECUTABLE -t 887563923 -p 100 -r
test $(whoami) == "root" || sudo setcap cap_sys_boot-ep $NXECUTABLE
else
echo setcap failed, skipping nx_huge_pages_test with CAP_SYS_BOOT enabled
fi
# Test without reboot permissions
if [ $(whoami) != "root" ] ; then
echo Running test with CAP_SYS_BOOT disabled
$NXECUTABLE -t 887563923 -p 100
else
echo Running as root, skipping nx_huge_pages_test with CAP_SYS_BOOT disabled
fi
)
RET=$?