From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:29752 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbgGIN6O (ORCPT ); Thu, 9 Jul 2020 09:58:14 -0400 Subject: Re: [kvm-unit-tests PATCH v11 8/9] s390x: css: msch, enable test References: <1594282068-11054-1-git-send-email-pmorel@linux.ibm.com> <1594282068-11054-9-git-send-email-pmorel@linux.ibm.com> <20200709134056.0d267b6c.cohuck@redhat.com> <20200709153055.6f2b5e59.cohuck@redhat.com> <4f861a9c-179b-5376-5f0f-dce30f31da71@linux.ibm.com> <20200709155241.3014e3d6.cohuck@redhat.com> From: Pierre Morel Message-ID: Date: Thu, 9 Jul 2020 15:58:07 +0200 MIME-Version: 1.0 In-Reply-To: <20200709155241.3014e3d6.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Cornelia Huck Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, thuth@redhat.com, drjones@redhat.com On 2020-07-09 15:52, Cornelia Huck wrote: > On Thu, 9 Jul 2020 15:41:56 +0200 > Pierre Morel wrote: > >> On 2020-07-09 15:30, Cornelia Huck wrote: >>> On Thu, 9 Jul 2020 15:12:05 +0200 >>> Pierre Morel wrote: >>> >>>> On 2020-07-09 13:40, Cornelia Huck wrote: >>>>> On Thu, 9 Jul 2020 10:07:47 +0200 >>>>> 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 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 >>>>>> Acked-by: Thomas Huth >>>>>> Reviewed-by: Cornelia Huck >>>>>> --- >>>>>> lib/s390x/css.h | 8 +++-- >>>>>> lib/s390x/css_lib.c | 72 +++++++++++++++++++++++++++++++++++++++++++++ >>>>>> s390x/css.c | 15 ++++++++++ >>>>>> 3 files changed, 92 insertions(+), 3 deletions(-) >>>>> >>>>> (...) >>>>> >>>>>> +/* >>>>>> + * css_msch: enable subchannel and set with specified ISC >>>>> >>>>> "css_enable: enable the subchannel with the 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) { >>>>> >>>>> I think you want (pmcw->flags & PMCW_ENABLE) == PMCW_ENABLE -- this >>>>> catches the case of "subchannel has been enabled before, but with a >>>>> different isc". >>>> >>>> If with a different ISC, we need to modify the ISC. >>>> Don't we ? >>> >>> I think that's a policy decision (I would probably fail and require a >>> disable before setting another isc, but that's a matter of taste). >>> >>> Regardless, I think the current check doesn't even catch the 'different >>> isc' case? >> >> hum, right. >> If it is OK I remove this one. >> And I must rework the same test I do later >> in this patch. > > So, you mean checking for PMCW_ENABLE? Or not at all? > > (I'd check for PMCW_ENABLE.) > - if ((pmcw->flags & flags) == flags) { + if ((pmcw->flags & (PMCW_ISC_MASK | PMCW_ENABLE)) == flags) { report_info("stsch: sch %08x already enabled", schid); return 0; } I keep both, otherwise I return 0 without setting the ISC. then I have another error: retry: /* Update the SCHIB to enable the channel and set the ISC */ + pmcw->flags &= ~(PMCW_ISC_MASK | PMCW_ENABLE); pmcw->flags |= flags; and finaly the same as the first later... - if ((pmcw->flags & flags) == flags) { + if ((pmcw->flags & (PMCW_ISC_MASK | PMCW_ENABLE)) == flags) { report_info("stsch: sch %08x successfully modified after %d retries", schid, retry_count); is better I think. What do you think? -- Pierre Morel IBM Lab Boeblingen