[PATCH] KVM: selftests: Check API version when creating VM

Ivan Orlov
2024-05-09T15:38:14Z

As it is said in the docs, we should always check the KVM API version
before running the KVM-based applications. Add the function which
queries the current KVM API version through `ioctl` to the `kvm_util.c`
file.

Add a new TEST_REQUIRE statement to the `vm_open` function in order
to verify the version of the KVM API before creating a VM.

Signed-off-by: Ivan Orlov <ivan.orlov@codethink.co.uk>
---
.../testing/selftests/kvm/include/kvm_util_base.h | 2 ++
tools/testing/selftests/kvm/lib/kvm_util.c | 14 ++++++++++++++
2 files changed, 16 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 3e0db283a46a..d7a83387ae33 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -38,6 +38,7 @@
#define kvm_static_assert(expr, ...) __kvm_static_assert(expr, ##__VA_ARGS__, #expr)

#define KVM_DEV_PATH "/dev/kvm"
+#define KVM_DEFAULT_API_VERSION 12
#define KVM_MAX_VCPUS 512

#define NSEC_PER_SEC 1000000000L
@@ -275,6 +276,7 @@ int get_kvm_intel_param_integer(const char *param);
int get_kvm_amd_param_integer(const char *param);

unsigned int kvm_check_cap(long cap);
+int kvm_get_api_version(void);

static inline bool kvm_has_cap(long cap)
{
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index b2262b5fad9e..58a5deccb388 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -176,6 +176,19 @@ unsigned int kvm_check_cap(long cap)
return (unsigned int)ret;
}

+int kvm_get_api_version(void)
+{
+ int ret;
+ int kvm_fd;
+
+ kvm_fd = open_kvm_dev_path_or_exit();
+ ret = __kvm_ioctl(kvm_fd, KVM_GET_API_VERSION, NULL);
+
+ close(kvm_fd);
+
+ return ret;
+}
+
void vm_enable_dirty_ring(struct kvm_vm *vm, uint32_t ring_size)
{
if (vm_check_cap(vm, KVM_CAP_DIRTY_LOG_RING_ACQ_REL))
@@ -190,6 +203,7 @@ static void vm_open(struct kvm_vm *vm)
vm->kvm_fd = _open_kvm_dev_path_or_exit(O_RDWR);

TEST_REQUIRE(kvm_has_cap(KVM_CAP_IMMEDIATE_EXIT));
+ TEST_REQUIRE(kvm_get_api_version() == KVM_DEFAULT_API_VERSION);

vm->fd = __kvm_ioctl(vm->kvm_fd, KVM_CREATE_VM, (void *)vm->type);
TEST_ASSERT(vm->fd >= 0, KVM_IOCTL_ERROR(KVM_CREATE_VM, vm->fd));
--
2.34.1