KVM: selftests: Add tests - invalid inputs for KVM_CREATE_GUEST_MEMFD

Test that invalid inputs for KVM_CREATE_GUEST_MEMFD, such as
non-page-aligned page size and invalid flags, are rejected by the
KVM_CREATE_GUEST_MEMFD with EINVAL

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Link: https://lore.kernel.org/r/20230825001729.1952858-1-ackerleytng@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: Ackerley Tng

tools/testing/selftests/kvm/guest_memfd_test.c

@@ -8,6 +8,7 @@
 #define _GNU_SOURCE
 #include "test_util.h"
 #include "kvm_util_base.h"
+#include <linux/bitmap.h>
 #include <linux/falloc.h>
 #include <sys/mman.h>
 #include <sys/types.h>
@@ -90,6 +91,52 @@ static void test_fallocate(int fd, size_t page_size, size_t total_size)
 	TEST_ASSERT(!ret, "fallocate to restore punched hole should succeed");
 }
 
+static void test_create_guest_memfd_invalid(struct kvm_vm *vm)
+{
+	uint64_t valid_flags = 0;
+	size_t page_size = getpagesize();
+	uint64_t flag;
+	size_t size;
+	int fd;
+
+	for (size = 1; size < page_size; size++) {
+		fd = __vm_create_guest_memfd(vm, size, 0);
+		TEST_ASSERT(fd == -1 && errno == EINVAL,
+			    "guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL",
+			    size);
+	}
+
+	if (thp_configured()) {
+		for (size = page_size * 2; size < get_trans_hugepagesz(); size += page_size) {
+			fd = __vm_create_guest_memfd(vm, size, KVM_GUEST_MEMFD_ALLOW_HUGEPAGE);
+			TEST_ASSERT(fd == -1 && errno == EINVAL,
+				    "guest_memfd() with non-hugepage-aligned page size '0x%lx' should fail with EINVAL",
+				    size);
+		}
+
+		valid_flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE;
+	}
+
+	for (flag = 1; flag; flag <<= 1) {
+		uint64_t bit;
+
+		if (flag & valid_flags)
+			continue;
+
+		fd = __vm_create_guest_memfd(vm, page_size, flag);
+		TEST_ASSERT(fd == -1 && errno == EINVAL,
+			    "guest_memfd() with flag '0x%lx' should fail with EINVAL",
+			    flag);
+
+		for_each_set_bit(bit, &valid_flags, 64) {
+			fd = __vm_create_guest_memfd(vm, page_size, flag | BIT_ULL(bit));
+			TEST_ASSERT(fd == -1 && errno == EINVAL,
+				    "guest_memfd() with flags '0x%llx' should fail with EINVAL",
+				    flag | BIT_ULL(bit));
+		}
+	}
+}
+
 
 int main(int argc, char *argv[])
 {
@@ -103,6 +150,8 @@ int main(int argc, char *argv[])
 
 	vm = vm_create_barebones();
 
+	test_create_guest_memfd_invalid(vm);
+
 	fd = vm_create_guest_memfd(vm, total_size, 0);
 
 	test_file_read_write(fd);

tools/testing/selftests/kvm/include/kvm_util_base.h

@@ -474,15 +474,22 @@ static inline uint64_t vm_get_stat(struct kvm_vm *vm, const char *stat_name)
 }
 
 void vm_create_irqchip(struct kvm_vm *vm);
-static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
+
+static inline int __vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
 					uint64_t flags)
 {
 	struct kvm_create_guest_memfd gmem = {
 		.size = size,
 		.flags = flags,
 	};
 
-	int fd = __vm_ioctl(vm, KVM_CREATE_GUEST_MEMFD, &gmem);
+	return __vm_ioctl(vm, KVM_CREATE_GUEST_MEMFD, &gmem);
+}
+
+static inline int vm_create_guest_memfd(struct kvm_vm *vm, uint64_t size,
+					uint64_t flags)
+{
+	int fd = __vm_create_guest_memfd(vm, size, flags);
 
 	TEST_ASSERT(fd >= 0, KVM_IOCTL_ERROR(KVM_CREATE_GUEST_MEMFD, fd));
 	return fd;