Re: [kvm-unit-tests PATCH v8 11/12] s390x: css: msch, enable test

Thomas Huth
2020-06-09T07:47:34Z

On 08/06/2020 10.13, Pierre Morel 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.
> - If the command succeeds but subchannel is not enabled 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 succesfuly.
> This some 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>
> ---
> lib/s390x/css_lib.c | 60 +++++++++++++++++++++++++++++++++++++++++++++
> s390x/css.c | 18 ++++++++++++++
> 2 files changed, 78 insertions(+)
>
> diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
> index dc5a512..831a116 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 +69,62 @@ out:
> scn, scn_found, dev_found);
> return schid;
> }
> +
> +int css_enable(int schid)
> +{
> + struct pmcw *pmcw = &schib.pmcw;
> + int retry_count = 0;
> + int cc;
> +
> + /* Read the SCHIB for this subchannel */
> + cc = stsch(schid, &schib);
> + if (cc) {
> + report_info("stsch failed with cc=%d", cc);
> + return cc;
> + }
> +
> + if (pmcw->flags & PMCW_ENABLE) {
> + report_info("stsch: sch %08x already enabled", schid);
> + return 0;
> + }
> +
> +retry:
> + /* Update the SCHIB to enable the channel */
> + pmcw->flags |= PMCW_ENABLE;
> +
> + /* 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 failed with cc=%d", cc);
> + return cc;
> + }
> +
> + /*
> + * Read the SCHIB again to verify the enablement
> + */
> + cc = stsch(schid, &schib);
> + if (cc) {
> + report_info("stsch failed with cc=%d", cc);
> + return cc;
> + }
> +
> + if (pmcw->flags & PMCW_ENABLE) {
> + report_info("Subchannel %08x enabled 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: enabling sch %08x failed after %d retries. pmcw flags: %x",
> + schid, retry_count, pmcw->flags);
> + return -1;
> +}
> diff --git a/s390x/css.c b/s390x/css.c
> index f0e8f47..6f58d4a 100644
> --- a/s390x/css.c
> +++ b/s390x/css.c
> @@ -40,11 +40,29 @@ static void test_enumerate(void)
> }
> }
>
> +static void test_enable(void)
> +{
> + int cc;
> +
> + if (!test_device_sid) {
> + report_skip("No device");
> + return;
> + }
> +
> + cc = css_enable(test_device_sid);
> +
> + if (cc)
> + report(0, "Failed to enable subchannel %08x", test_device_sid);
> + else
> + report(1, "Subchannel %08x enabled", test_device_sid);

Could you please write this as:

report(cc == 1, "Enable subchannel %08x", test_device_sid);

... checking for a right value is the whole point of the first parameter
of report() :-)

Thanks,
Thomas