KVM: selftests: Macrofy vm_get_stat() to auto-generate stat name string

Turn vm_get_stat() into a macro that generates a string for the stat name,
as opposed to taking a string.  This will allow hardening stat usage in
the future to generate errors on unknown stats at compile time.

No functional change intended.

Link: https://lore.kernel.org/r/20250111005049.1247555-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

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

@@ -534,13 +534,13 @@ void read_stat_data(int stats_fd, struct kvm_stats_header *header,
 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;
-}
+#define vm_get_stat(vm, stat)				\
+({							\
+	uint64_t data;					\
+							\
+	__vm_get_stat(vm, #stat, &data, 1);		\
+	data;						\
+})
 
 void vm_create_irqchip(struct kvm_vm *vm);
 

tools/testing/selftests/kvm/x86/dirty_log_page_splitting_test.c

@@ -41,9 +41,9 @@ struct kvm_page_stats {
 
 static void get_page_stats(struct kvm_vm *vm, struct kvm_page_stats *stats, const char *stage)
 {
-	stats->pages_4k = vm_get_stat(vm, "pages_4k");
-	stats->pages_2m = vm_get_stat(vm, "pages_2m");
-	stats->pages_1g = vm_get_stat(vm, "pages_1g");
+	stats->pages_4k = vm_get_stat(vm, pages_4k);
+	stats->pages_2m = vm_get_stat(vm, pages_2m);
+	stats->pages_1g = vm_get_stat(vm, pages_1g);
 	stats->hugepages = stats->pages_2m + stats->pages_1g;
 
 	pr_debug("\nPage stats after %s: 4K: %ld 2M: %ld 1G: %ld huge: %ld\n",

tools/testing/selftests/kvm/x86/nx_huge_pages_test.c

@@ -73,7 +73,7 @@ static void check_2m_page_count(struct kvm_vm *vm, int expected_pages_2m)
 {
 	int actual_pages_2m;
 
-	actual_pages_2m = vm_get_stat(vm, "pages_2m");
+	actual_pages_2m = vm_get_stat(vm, pages_2m);
 
 	TEST_ASSERT(actual_pages_2m == expected_pages_2m,
 		    "Unexpected 2m page count. Expected %d, got %d",
@@ -84,7 +84,7 @@ static void check_split_count(struct kvm_vm *vm, int expected_splits)
 {
 	int actual_splits;
 
-	actual_splits = vm_get_stat(vm, "nx_lpage_splits");
+	actual_splits = vm_get_stat(vm, nx_lpage_splits);
 
 	TEST_ASSERT(actual_splits == expected_splits,
 		    "Unexpected NX huge page split count. Expected %d, got %d",