powerpc/sstep: Let compute tests specify a required cpu feature

An a array of struct compute_test's are used to declare tests for
compute instructions. Add a cpu_feature field to struct compute_test as
an optional way to specify a cpu feature that must be present. If not
present then skip the test.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200525025923.19843-4-jniethe5@gmail.com

arch/powerpc/lib/test_emulate_step.c

@@ -625,6 +625,7 @@ static void __init run_tests_load_store(void)
 
 struct compute_test {
 	char *mnemonic;
+	unsigned long cpu_feature;
 	struct {
 		char *descr;
 		unsigned long flags;
@@ -1068,6 +1069,11 @@ static void __init run_tests_compute(void)
 	for (i = 0; i < ARRAY_SIZE(compute_tests); i++) {
 		test = &compute_tests[i];
 
+		if (test->cpu_feature && !early_cpu_has_feature(test->cpu_feature)) {
+			show_result(test->mnemonic, "SKIP (!CPU_FTR)");
+			continue;
+		}
+
 		for (j = 0; j < MAX_SUBTESTS && test->subtests[j].descr; j++) {
 			instr = test->subtests[j].instr;
 			flags = test->subtests[j].flags;