[kvm-unit-tests PATCH v11 8/9] s390x: css: msch, enable test

Pierre Morel
2020-07-09T08:08:00Z

A second step when testing the channel subsystem is to prepare a channel
for use.
This includes:
- Get the current subchannel Information Block (SCHIB) using STSCH
- Update it in memory to set the ENABLE bit and the specified ISC
- Tell the CSS that the SCHIB has been modified using MSCH
- Get the SCHIB from the CSS again to verify that the subchannel is
enabled and uses the specified ISC.
- If the command succeeds but subchannel is not enabled or the ISC
field is not as expected, retry a predefined retries count.
- If the command fails, report the failure and do not retry, even
if cc indicates a busy/status pending as we do not expect this.

This tests the MSCH instruction to enable a channel successfully.
Retries are done and in case of error, and if the retries count
is exceeded, a report is made.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
lib/s390x/css.h | 8 +++--
lib/s390x/css_lib.c | 72 +++++++++++++++++++++++++++++++++++++++++++++
s390x/css.c | 15 ++++++++++
3 files changed, 92 insertions(+), 3 deletions(-)

diff --git a/lib/s390x/css.h b/lib/s390x/css.h
index 0ddceb1..106479d 100644
--- a/lib/s390x/css.h
+++ b/lib/s390x/css.h
@@ -71,8 +71,9 @@ struct scsw {

struct pmcw {
uint32_t intparm;
-#define PMCW_DNV 0x0001
-#define PMCW_ENABLE 0x0080
+#define PMCW_DNV 0x0001
+#define PMCW_ENABLE 0x0080
+#define PMCW_ISC_SHIFT 11
uint16_t flags;
uint16_t devnum;
uint8_t lpm;
@@ -251,6 +252,7 @@ void dump_orb(struct orb *op);

int css_enumerate(void);
#define MAX_ENABLE_RETRIES 5
-int css_enable(int schid);

+#define IO_SCH_ISC 3
+int css_enable(int schid, int isc);
#endif
diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
index fd087ce..eda68a4 100644
--- a/lib/s390x/css_lib.c
+++ b/lib/s390x/css_lib.c
@@ -15,6 +15,7 @@
#include <string.h>
#include <interrupt.h>
#include <asm/arch_def.h>
+#include <asm/time.h>

#include <css.h>

@@ -68,3 +69,74 @@ out:
scn, scn_found, dev_found);
return schid;
}
+
+/*
+ * css_msch: enable subchannel and set with specified ISC
+ * @schid: Subchannel Identifier
+ * @isc : number of the interruption subclass to use
+ * Return value:
+ * On success: 0
+ * On error the CC of the faulty instruction
+ * or -1 if the retry count is exceeded.
+ */
+int css_enable(int schid, int isc)
+{
+ struct pmcw *pmcw = &schib.pmcw;
+ int retry_count = 0;
+ uint16_t flags;
+ int cc;
+
+ /* Read the SCHIB for this subchannel */
+ cc = stsch(schid, &schib);
+ if (cc) {
+ report_info("stsch: sch %08x failed with cc=%d", schid, cc);
+ return cc;
+ }
+
+ flags = PMCW_ENABLE | (isc << PMCW_ISC_SHIFT);
+ if ((pmcw->flags & flags) == flags) {
+ report_info("stsch: sch %08x already enabled", schid);
+ return 0;
+ }
+
+retry:
+ /* Update the SCHIB to enable the channel and set the ISC */
+ pmcw->flags |= flags;
+
+ /* Tell the CSS we want to modify the subchannel */
+ cc = msch(schid, &schib);
+ if (cc) {
+ /*
+ * If the subchannel is status pending or
+ * if a function is in progress,
+ * we consider both cases as errors.
+ */
+ report_info("msch: sch %08x failed with cc=%d", schid, cc);
+ return cc;
+ }
+
+ /*
+ * Read the SCHIB again to verify the enablement
+ */
+ cc = stsch(schid, &schib);
+ if (cc) {
+ report_info("stsch: updating sch %08x failed with cc=%d",
+ schid, cc);
+ return cc;
+ }
+
+ if ((pmcw->flags & flags) == flags) {
+ report_info("stsch: sch %08x successfully modified after %d retries",
+ schid, retry_count);
+ return 0;
+ }
+
+ if (retry_count++ < MAX_ENABLE_RETRIES) {
+ mdelay(10); /* the hardware was not ready, give it some time */
+ goto retry;
+ }
+
+ report_info("msch: modifying sch %08x failed after %d retries. pmcw flags: %04x",
+ schid, retry_count, pmcw->flags);
+ return -1;
+}
diff --git a/s390x/css.c b/s390x/css.c
index e19ffc8..f314a0c 100644
--- a/s390x/css.c
+++ b/s390x/css.c
@@ -31,11 +31,26 @@ static void test_enumerate(void)
report(0, "No I/O device found");
}

+static void test_enable(void)
+{
+ int cc;
+
+ if (!test_device_sid) {
+ report_skip("No device");
+ return;
+ }
+
+ cc = css_enable(test_device_sid, IO_SCH_ISC);
+
+ report(cc == 0, "Enable subchannel %08x", test_device_sid);
+}
+
static struct {
const char *name;
void (*func)(void);
} tests[] = {
{ "enumerate (stsch)", test_enumerate },
+ { "enable (msch)", test_enable },
{ NULL, NULL }
};

--
2.25.1