Re: [kvm-unit-tests PATCH v4 6/9] s390x: css: stsch, enumeration test

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On 2019-12-12 11:18, Cornelia Huck wrote:
On Wed, 11 Dec 2019 16:46:07 +0100
Pierre Morel <pmorel@xxxxxxxxxxxxx> wrote:

First step for testing the channel subsystem is to enumerate the css and
retrieve the css devices.

This tests the success of STSCH I/O instruction, we do not test the
reaction of the VM for an instruction with wrong parameters.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
  lib/s390x/css.h     |  1 +
  s390x/Makefile      |  2 ++
  s390x/css.c         | 88 +++++++++++++++++++++++++++++++++++++++++++++
  s390x/unittests.cfg |  4 +++
  4 files changed, 95 insertions(+)
  create mode 100644 s390x/css.c

diff --git a/s390x/css.c b/s390x/css.c
new file mode 100644
index 0000000..dfab35f
--- /dev/null
+++ b/s390x/css.c
@@ -0,0 +1,88 @@
+/*
+ * Channel Subsystem tests
+ *
+ * Copyright (c) 2019 IBM Corp
+ *
+ * Authors:
+ *  Pierre Morel <pmorel@xxxxxxxxxxxxx>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#include <libcflat.h>
+#include <alloc_phys.h>
+#include <asm/page.h>
+#include <string.h>
+#include <interrupt.h>
+#include <asm/arch_def.h>
+#include <asm/time.h>
+
+#include <css.h>
+
+#define SID_ONE		0x00010000
+
+static struct schib schib;
+static int test_device_sid;
+
+static void test_enumerate(void)
+{
+	struct pmcw *pmcw = &schib.pmcw;
+	int cc;
+	int scn;
+	int scn_found = 0;
+
+	for (scn = 0; scn < 0xffff; scn++) {
+		cc = stsch(scn|SID_ONE, &schib);
+		switch (cc) {
+		case 0:		/* 0 means SCHIB stored */
+			break;
+		case 3:		/* 3 means no more channels */
+			goto out;
+		default:	/* 1 or 2 should never happened for STSCH */
+			report(0, "Unexpected cc=%d on scn 0x%x", cc, scn);

Spell out "subchannel number"?

Yes I can do this.


+			return;
+		}
+		if (cc)
+			break;

Isn't that redundant?
fully.


+		/* We silently only support type 0, a.k.a. I/O channels */

s/silently/currently/ ?

OK


+		if (PMCW_CHANNEL_TYPE(pmcw) != 0)
+			continue;
+		/* We ignore I/O channels without valid devices */
+		if (!(pmcw->flags & PMCW_DNV))
+			continue;
+		/* We keep track of the first device as our test device */
+		if (!test_device_sid)
+			test_device_sid = scn|SID_ONE;
+		scn_found++;
+	}
+out:
+	if (!scn_found) {
+		report(0, "Devices, Tested: %d, no I/O type found", scn);

It's no I/O _devices_ found, isn't it? There might have been I/O
subchannels, but none with a valid device...

yes, I will update the stats.


+		return;
+	}
+	report(1, "Devices, tested: %d, I/O type: %d", scn, scn_found);

As you're testing this anyway: what about tracking _all_ numbers here?
I.e., advance a counter for I/O subchannels as well, even if !dnv, and
have an output like >
"Tested subchannels: 20, I/O subchannels: 18, I/O devices: 10"

or so?

Yes, will do.



+}
+
+static struct {
+	const char *name;
+	void (*func)(void);
+} tests[] = {
+	{ "enumerate (stsch)", test_enumerate },
+	{ NULL, NULL }
+};
+
+int main(int argc, char *argv[])
+{
+	int i;
+
+	report_prefix_push("Channel Sub-System");

s/Channel Sub-System/Channel Subsystem/ ?

OK, (it was because of "CSS").


+	for (i = 0; tests[i].name; i++) {
+		report_prefix_push(tests[i].name);
+		tests[i].func();
+		report_prefix_pop();
+	}
+	report_prefix_pop();
+
+	return report_summary();
+}

This basically looks sane to me now.

Just some additional considerations (we can do that on top, no need to
do surgery here right now):

I currently have the (not sure how sensible) idea to add some optional
testing for vfio-ccw, and this would obviously need some I/O routines as
well. So, in the long run, it would be good if something like this
stsch-loop could be factored out to a kind of library function. Just
some thoughts for now :)


Yes, could be useful.

Thanks,
Regards,
Pierre


--
Pierre Morel
IBM Lab Boeblingen




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