KVM: selftests: Add NX huge pages test

There's currently no test coverage of NX hugepages in KVM selftests, so
add a basic test to ensure that the feature works as intended.

The test creates a VM with a data slot backed with huge pages. The
memory in the data slot is filled with op-codes for the return
instruction. The guest then executes a series of accesses on the memory,
some reads, some instruction fetches. After each operation, the guest
exits and the test performs some checks on the backing page counts to
ensure that NX page splitting an reclaim work as expected.

Reviewed-by: David Matlack <dmatlack@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220613212523.3436117-7-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index cec3af45e18d..c6c1d66136d6 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -345,6 +345,17 @@ void read_stat_data(int stats_fd, struct kvm_stats_header *header,
 		    struct kvm_stats_desc *desc, uint64_t *data,
 		    size_t max_elements);
 
+void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
+		   size_t max_elements);
+
+static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)
+{
+	uint64_t data;
+
+	__vm_get_stat(vm, stat_name, &data, 1);
+	return data;
+}
+
 void vm_create_irqchip(struct kvm_vm *vm);
 
 void vm_set_user_memory_region(struct kvm_vm *vm, uint32_t slot, uint32_t flags,