[PATCH kvm-unit-tests v1 4/8] s390x: Add tests for STCRW

[Nico Boehr <nrb@linux.ibm.com>]

The test consists of two parts: First a simple check to ensure we
enforce an aligned address. We test misalignment by 1 and 2 bytes.

The second part tests the handling of pending Channel Reports (CR). We
first assume no CR is initally pending and check STCRW returns
accordingly. Then, we generate a CR by resetting a Channel Path using
RCHP and make sure this results in exactly one CRW being generated which
has a Reporting-Source Code (RSC) corresponding to the Channel Path
facility.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
---
 lib/s390x/css.h     | 17 ++++++++++
 lib/s390x/css_lib.c | 60 +++++++++++++++++++++++++++++++++
 s390x/css.c         | 82 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 159 insertions(+)

diff --git a/lib/s390x/css.h b/lib/s390x/css.h
index 0db8a28166f6..a6a68577248b 100644
--- a/lib/s390x/css.h
+++ b/lib/s390x/css.h
@@ -266,6 +266,20 @@ static inline int rchp(unsigned long chpid)
 	return cc;
 }
 
+static inline int stcrw(uint32_t *crw)
+{
+	int cc;
+
+	asm volatile(
+		"	stcrw	%[crw]\n"
+		"	ipm	%[cc]\n"
+		"	srl	%[cc],28"
+		: [cc] "=d" (cc)
+		: [crw] "Q" (*crw)
+		: "cc", "memory");
+	return cc;
+}
+
 /* Debug functions */
 char *dump_pmcw_flags(uint16_t f);
 char *dump_scsw_flags(uint32_t f);
@@ -294,6 +308,9 @@ int css_residual_count(unsigned int schid);
 void enable_io_isc(uint8_t isc);
 int wait_and_check_io_completion(int schid);
 
+int css_find_installed_chpid(int sid, uint8_t *chpid_out);
+int css_generate_crw(int sid);
+
 /*
  * CHSC definitions
  */
diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
index 80e9e078b0f6..a9f5097f3486 100644
--- a/lib/s390x/css_lib.c
+++ b/lib/s390x/css_lib.c
@@ -504,3 +504,63 @@ void enable_io_isc(uint8_t isc)
 	value = (uint64_t)isc << 24;
 	lctlg(6, value);
 }
+
+static int is_path_installed(struct schib *schib, int chp_idx)
+{
+	return schib->pmcw.pim & BIT(7 - chp_idx);
+}
+
+/*
+ * css_find_installed_chpid: find any installed CHPID
+ * @sid: subsystem-identification word
+ * @chpid_out: store the found chpid here, left alone if none found
+ *
+ * returns 0 on success, -1 if no chpid found any other value
+ * indicates the condition code of a failing STSCH instruction
+ */
+int css_find_installed_chpid(int sid, uint8_t *chpid_out)
+{
+	int cc;
+
+	cc = stsch(sid, &schib);
+	if (cc) {
+		report_fail("%s: sch %08x failed with cc=%d", __func__, sid, cc);
+		return cc;
+	}
+
+	for (int i = 0; i < ARRAY_SIZE(schib.pmcw.chpid); i++) {
+		if (is_path_installed(&schib, i)) {
+			*chpid_out = schib.pmcw.chpid[i];
+			return 0;
+		}
+	}
+
+	return -1;
+}
+
+/*
+ * css_generate_crw: Generate a CRW by issuing RCHP on any channel path
+ * @sid: subsystem-identification word
+ *
+ * returns 0 when a CRW was generated, -1 if no chpid found.
+ */
+int css_generate_crw(int sid)
+{
+	int ret, cc;
+	uint8_t chpid;
+
+	report_prefix_push("Generate CRW");
+
+	ret = css_find_installed_chpid(sid, &chpid);
+	if (ret) {
+		report_fail("No CHPID found: ret=%d", ret);
+		return -1;
+	}
+
+	cc = rchp(chpid);
+	report(!cc, "rhcp cc != 0");
+
+	report_prefix_pop();
+
+	return 0;
+}
diff --git a/s390x/css.c b/s390x/css.c
index afe1f71bb576..3f9dbac173e3 100644
--- a/s390x/css.c
+++ b/s390x/css.c
@@ -381,6 +381,87 @@ static void test_msch(void)
 	report_prefix_pop();
 }
 
+static void check_stcrw_no_crw_available(void)
+{
+	uint32_t crw = 0xfeedc0fe;
+	int cc;
+
+	report_prefix_push("No CRW available");
+	cc = stcrw(&crw);
+	report(cc == 1, "cc == 1");
+	report(!crw, "stored zeroes in crw");
+	report_prefix_pop();
+}
+
+static int check_stcrw_crw_available(void)
+{
+	const uint32_t magic = 0xfeedc0fe;
+	uint32_t crw = magic;
+	int cc;
+
+	report_prefix_push("CRW available");
+	cc = stcrw(&crw);
+	report(!cc, "cc is zero");
+	report(crw != magic, "stored crw");
+	report_prefix_pop();
+
+	return crw;
+}
+
+static uint32_t crw_get_rsc(uint32_t crw)
+{
+	const int rsc_begin = 4;
+	const int rsc_end = 8;
+
+	return (crw & GENMASK(31 - rsc_begin, 31 - rsc_end)) >> 24;
+}
+
+#define CRW_RSC_CHP 4
+static void test_stcrw(void)
+{
+	const int align_to = 4;
+	int res;
+	uint32_t crw;
+
+	if (!test_device_sid) {
+		report_skip("No device");
+		return;
+	}
+
+	report_prefix_push("Unaligned");
+	for (int i = 1; i < align_to; i *= 2) {
+		report_prefix_pushf("%d", i);
+
+		expect_pgm_int();
+		stcrw((uint32_t *)(alignment_test_page + i));
+		check_pgm_int_code(PGM_INT_CODE_SPECIFICATION);
+
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+
+	report_prefix_push("No CRW available initally");
+	check_stcrw_no_crw_available();
+	report_prefix_pop();
+
+	res = css_generate_crw(test_device_sid);
+	if (res) {
+		report_skip("Couldn't generate CRW");
+		report_prefix_pop();
+		return;
+	}
+
+	crw = check_stcrw_crw_available();
+
+	report_prefix_push("CRW available");
+	report(crw_get_rsc(crw) == CRW_RSC_CHP, "CRW has Channel Path RSC");
+	report_prefix_pop();
+
+	report_prefix_push("No more CRWs pending");
+	check_stcrw_no_crw_available();
+	report_prefix_pop();
+}
+
 static struct {
 	const char *name;
 	void (*func)(void);
@@ -394,6 +475,7 @@ static struct {
 	{ "measurement block format0", test_schm_fmt0 },
 	{ "measurement block format1", test_schm_fmt1 },
 	{ "msch", test_msch },
+	{ "stcrw", test_stcrw },
 	{ NULL, NULL }
 };
 
-- 
2.31.1