From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:7284 "EHLO mx0b-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726410AbgGIOiq (ORCPT ); Thu, 9 Jul 2020 10:38:46 -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> <20200709162210.7fe6f9cb.cohuck@redhat.com> From: Pierre Morel Message-ID: Date: Thu, 9 Jul 2020 16:38:39 +0200 MIME-Version: 1.0 In-Reply-To: <20200709162210.7fe6f9cb.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 16:22, Cornelia Huck wrote: > On Thu, 9 Jul 2020 15:58:07 +0200 > Pierre Morel wrote: > >> 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: > >>>>>>> (...) >>>>>>> >>>>>>>> +/* >>>>>>>> + * 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. > > Ah, I missed the 'return 0'. > >> then I have another error: >> >> retry: >> /* Update the SCHIB to enable the channel and set the ISC */ >> + pmcw->flags &= ~(PMCW_ISC_MASK | PMCW_ENABLE); > > Maybe ~PMCW_ISC_MASK is enough? yes > >> 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) { > > I think you can keep that as-is. I don't thing so, I just stored the pmcw. if ISC is stored as 3 and I want 1 it is a false positive. Same error as you showed me before. ? > >> report_info("stsch: sch %08x successfully modified >> after %d retries", >> schid, retry_count); >> >> >> is better I think. >> What do you think? > > It's probably the right direction. > Thanks, Pierre -- Pierre Morel IBM Lab Boeblingen