Re: [kvm-unit-tests PATCH v3 7/9] s390x: css: msch, enable test

Cornelia Huck
2019-12-09T16:54:43Z

On Fri, 6 Dec 2019 17:26:26 +0100
Pierre Morel <pmorel@linux.ibm.com> wrote:

> 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
> - 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.
>
> This tests the success of the MSCH instruction by enabling a channel.
>
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
> s390x/css.c | 39 +++++++++++++++++++++++++++++++++++++++
> 1 file changed, 39 insertions(+)
>
> diff --git a/s390x/css.c b/s390x/css.c
> index 3d4a986..4c0031c 100644
> --- a/s390x/css.c
> +++ b/s390x/css.c
> @@ -58,11 +58,50 @@ static void test_enumerate(void)
> report("Tested %d devices, %d found", 1, scn, found);
> }
>
> +static void test_enable(void)
> +{
> + struct pmcw *pmcw = &schib.pmcw;
> + int cc;
> +
> + if (!test_device_sid) {
> + report_skip("No device");
> + return;
> + }
> + /* Read the SCIB for this subchannel */

s/SCIB/SCHIB/

> + cc = stsch(test_device_sid, &schib);
> + if (cc) {
> + report("stsch cc=%d", 0, cc);
> + return;
> + }
> + /* Update the SCHIB to enable the channel */
> + pmcw->flags |= PMCW_ENABLE;
> +
> + /* Tell the CSS we want to modify the subchannel */
> + cc = msch(test_device_sid, &schib);
> + if (cc) {
> + report("msch cc=%d", 0, cc);

So you expect the subchannel to be idle? Probably true, especially as
QEMU has no reason to post an unsolicited interrupt for a test device.

> + return;
> + }
> +
> + /* Read the SCHIB again to verify the enablement */
> + cc = stsch(test_device_sid, &schib);
> + if (cc) {
> + report("stsch cc=%d", 0, cc);
> + return;
> + }
> + if (!(pmcw->flags & PMCW_ENABLE)) {
> + report("Enable failed. pmcw: %x", 0, pmcw->flags);

This check is fine when running under KVM. If this test is modified to
run under z/VM in the future, you probably should retry here: I've seen
the enable bit 'stick' only after the second msch() there.

> + return;
> + }
> + report("Tested", 1);
> +}
> +
> static struct {
> const char *name;
> void (*func)(void);
> } tests[] = {
> { "enumerate (stsch)", test_enumerate },
> + { "enable (msch)", test_enable },
> { NULL, NULL }
> };
>