KVM: s390: selftests: Add regression tests for PLO subfunctions

Extend the existing regression test framework for s390x CPU subfunctions
to include tests for the Perform Locked Operation (PLO) subfunction
functions.

PLO was introduced in the very first 64-bit machine generation.
Hence it is assumed PLO is always installed in the Z Arch.
The test procedure follows the established pattern.

Suggested-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Hariharan Mari <hari55@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Link: https://lore.kernel.org/r/20240823130947.38323-6-hari55@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20240823130947.38323-6-hari55@linux.ibm.com>

Author: Hariharan Mari

tools/testing/selftests/kvm/s390x/cpumodel_subfuncs_test.c

@@ -19,6 +19,8 @@
 
 #include "kvm_util.h"
 
+#define PLO_FUNCTION_MAX 256
+
 /* Query available CPU subfunctions */
 struct kvm_s390_vm_cpu_subfunc cpu_subfunc;
 
@@ -33,6 +35,31 @@ static void get_cpu_machine_subfuntions(struct kvm_vm *vm,
 	TEST_ASSERT(!r, "Get cpu subfunctions failed r=%d errno=%d", r, errno);
 }
 
+static inline int plo_test_bit(unsigned char nr)
+{
+	unsigned long function = nr | 0x100;
+	int cc;
+
+	asm volatile("	lgr	0,%[function]\n"
+			/* Parameter registers are ignored for "test bit" */
+			"	plo	0,0,0,0(0)\n"
+			"	ipm	%0\n"
+			"	srl	%0,28\n"
+			: "=d" (cc)
+			: [function] "d" (function)
+			: "cc", "0");
+	return cc == 0;
+}
+
+/* Testing Perform Locked Operation (PLO) CPU subfunction's ASM block */
+static void test_plo_asm_block(u8 (*query)[32])
+{
+	for (int i = 0; i < PLO_FUNCTION_MAX; ++i) {
+		if (plo_test_bit(i))
+			(*query)[i >> 3] |= 0x80 >> (i & 7);
+	}
+}
+
 /* Testing Crypto Compute Message Authentication Code (KMAC) CPU subfunction's ASM block */
 static void test_kmac_asm_block(u8 (*query)[16])
 {
@@ -196,6 +223,11 @@ struct testdef {
 	testfunc_t test;
 	int facility_bit;
 } testlist[] = {
+	/*
+	 * PLO was introduced in the very first 64-bit machine generation.
+	 * Hence it is assumed PLO is always installed in Z Arch.
+	 */
+	{ "PLO", cpu_subfunc.plo, sizeof(cpu_subfunc.plo), test_plo_asm_block, 1 },
 	/* MSA - Facility bit 17 */
 	{ "KMAC", cpu_subfunc.kmac, sizeof(cpu_subfunc.kmac), test_kmac_asm_block, 17 },
 	{ "KMC", cpu_subfunc.kmc, sizeof(cpu_subfunc.kmc), test_kmc_asm_block, 17 },