[PATCH v2 5/5] KVM: s390: selftests: Add regression tests for PLO subfunctions

[Hariharan Mari <hari55@linux.ibm.com>]

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>
---
 .../kvm/s390x/cpumodel_subfuncs_test.c        | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/tools/testing/selftests/kvm/s390x/cpumodel_subfuncs_test.c b/tools/testing/selftests/kvm/s390x/cpumodel_subfuncs_test.c
index c31f445c6f03..255984a52365 100644
--- a/tools/testing/selftests/kvm/s390x/cpumodel_subfuncs_test.c
+++ b/tools/testing/selftests/kvm/s390x/cpumodel_subfuncs_test.c
@@ -20,6 +20,8 @@
 
 #include "kvm_util.h"
 
+#define U8_MAX  ((u8)~0U)
+
 /**
  * Query available CPU subfunctions
  */
@@ -37,6 +39,33 @@ 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 = (unsigned long)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 <= U8_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
@@ -237,6 +266,11 @@ 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 },
-- 
2.45.2