[RFC PATCH v4 4/9] KVM: selftests: Make a generic helper to get vm guest mode strings

[Yanan Wang <wangyanan55@huawei.com>]

For generality and conciseness, make an API which can be used in all
kvm libs and selftests to get vm guest mode strings. And the index i
is checked in the API in case of possiable faults.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  |  4 +--
 tools/testing/selftests/kvm/lib/kvm_util.c    | 29 ++++++++++++-------
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 2d7eb6989e83..f52a7492f47f 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -68,9 +68,6 @@ enum vm_guest_mode {
 #define MIN_PAGE_SIZE		(1U << MIN_PAGE_SHIFT)
 #define PTES_PER_MIN_PAGE	ptes_per_page(MIN_PAGE_SIZE)
 
-#define vm_guest_mode_string(m) vm_guest_mode_string[m]
-extern const char * const vm_guest_mode_string[];
-
 struct vm_guest_mode_params {
 	unsigned int pa_bits;
 	unsigned int va_bits;
@@ -84,6 +81,7 @@ int vm_enable_cap(struct kvm_vm *vm, struct kvm_enable_cap *cap);
 int vcpu_enable_cap(struct kvm_vm *vm, uint32_t vcpu_id,
 		    struct kvm_enable_cap *cap);
 void vm_enable_dirty_ring(struct kvm_vm *vm, uint32_t ring_size);
+const char *vm_guest_mode_string(uint32_t i);
 
 struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm);
 void kvm_vm_free(struct kvm_vm *vmp);
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index d787cb802b4a..cc22c4ab7d67 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -141,17 +141,24 @@ static void vm_open(struct kvm_vm *vm, int perm)
 		"rc: %i errno: %i", vm->fd, errno);
 }
 
-const char * const vm_guest_mode_string[] = {
-	"PA-bits:52,  VA-bits:48,  4K pages",
-	"PA-bits:52,  VA-bits:48, 64K pages",
-	"PA-bits:48,  VA-bits:48,  4K pages",
-	"PA-bits:48,  VA-bits:48, 64K pages",
-	"PA-bits:40,  VA-bits:48,  4K pages",
-	"PA-bits:40,  VA-bits:48, 64K pages",
-	"PA-bits:ANY, VA-bits:48,  4K pages",
-};
-_Static_assert(sizeof(vm_guest_mode_string)/sizeof(char *) == NUM_VM_MODES,
-	       "Missing new mode strings?");
+const char *vm_guest_mode_string(uint32_t i)
+{
+	static const char * const strings[] = {
+		[VM_MODE_P52V48_4K]	= "PA-bits:52,  VA-bits:48,  4K pages",
+		[VM_MODE_P52V48_64K]	= "PA-bits:52,  VA-bits:48, 64K pages",
+		[VM_MODE_P48V48_4K]	= "PA-bits:48,  VA-bits:48,  4K pages",
+		[VM_MODE_P48V48_64K]	= "PA-bits:48,  VA-bits:48, 64K pages",
+		[VM_MODE_P40V48_4K]	= "PA-bits:40,  VA-bits:48,  4K pages",
+		[VM_MODE_P40V48_64K]	= "PA-bits:40,  VA-bits:48, 64K pages",
+		[VM_MODE_PXXV48_4K]	= "PA-bits:ANY, VA-bits:48,  4K pages",
+	};
+	_Static_assert(sizeof(strings)/sizeof(char *) == NUM_VM_MODES,
+		       "Missing new mode strings?");
+
+	TEST_ASSERT(i < NUM_VM_MODES, "Guest mode ID %d too big", i);
+
+	return strings[i];
+}
 
 const struct vm_guest_mode_params vm_guest_mode_params[] = {
 	{ 52, 48,  0x1000, 12 },
-- 
2.23.0