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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 24 Jul 2019 10:17:45 +0100 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x6O9Hhxv61341868 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 24 Jul 2019 09:17:43 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7C747AE04D; Wed, 24 Jul 2019 09:17:43 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 36F2FAE057; Wed, 24 Jul 2019 09:17:43 +0000 (GMT) Received: from pomme.lab.toulouse-stg.fr.ibm.com (unknown [9.101.4.33]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 24 Jul 2019 09:17:43 +0000 (GMT) Subject: Re: [PATCH v5 4/4] powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails To: Vaibhav Jain , linuxppc-dev@lists.ozlabs.org References: <20190723161357.26718-1-vaibhav@linux.ibm.com> <20190723161357.26718-5-vaibhav@linux.ibm.com> From: Laurent Dufour Date: Wed, 24 Jul 2019 11:17:42 +0200 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190723161357.26718-5-vaibhav@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19072409-0008-0000-0000-000003004765 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19072409-0009-0000-0000-0000226DD738 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-07-24_03:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1907240103 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Oliver O'Halloran , "Aneesh Kumar K . V" , David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 23/07/2019 à 18:13, Vaibhav Jain a écrit : > In some cases initial bind of scm memory for an lpar can fail if > previously it wasn't released using a scm-unbind hcall. This situation > can arise due to panic of the previous kernel or forced lpar > fadump. In such cases the H_SCM_BIND_MEM return a H_OVERLAP error. > > To mitigate such cases the patch updates papr_scm_probe() to force a > call to drc_pmem_unbind() in case the initial bind of scm memory fails > with EBUSY error. In case scm-bind operation again fails after the > forced scm-unbind then we follow the existing error path. We also > update drc_pmem_bind() to handle the H_OVERLAP error returned by phyp > and indicate it as a EBUSY error back to the caller. > > Suggested-by: "Oliver O'Halloran" > Signed-off-by: Vaibhav Jain > Reviewed-by: Oliver O'Halloran > --- > Change-log: > > v5: > * None. Re-spinning the patchset. > > v4: > * None. Re-spinning the patchset. > > v3: > * Minor update to a code comment. [Oliver] > > v2: > * Moved the retry code from drc_pmem_bind() to papr_scm_probe() > [Oliver] > * Changed the type of variable 'rc' in drc_pmem_bind() to > int64_t. [Oliver] > --- > arch/powerpc/platforms/pseries/papr_scm.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c > index 82568a7e0a7c..2c07908359b2 100644 > --- a/arch/powerpc/platforms/pseries/papr_scm.c > +++ b/arch/powerpc/platforms/pseries/papr_scm.c > @@ -44,8 +44,9 @@ struct papr_scm_priv { > static int drc_pmem_bind(struct papr_scm_priv *p) > { > unsigned long ret[PLPAR_HCALL_BUFSIZE]; > - uint64_t rc, token; > uint64_t saved = 0; > + uint64_t token; > + int64_t rc; > > /* > * When the hypervisor cannot map all the requested memory in a single > @@ -65,6 +66,10 @@ static int drc_pmem_bind(struct papr_scm_priv *p) > } while (rc == H_BUSY); > > if (rc) { > + /* H_OVERLAP needs a separate error path */ > + if (rc == H_OVERLAP) > + return -EBUSY; > + > dev_err(&p->pdev->dev, "bind err: %lld\n", rc); > return -ENXIO; > } > @@ -404,6 +409,14 @@ static int papr_scm_probe(struct platform_device *pdev) > > /* request the hypervisor to bind this region to somewhere in memory */ > rc = drc_pmem_bind(p); > + > + /* If phyp says drc memory still bound then force unbound and retry */ > + if (rc == -EBUSY) { > + dev_warn(&pdev->dev, "Retrying bind after unbinding\n"); > + drc_pmem_unbind(p); > + rc = drc_pmem_bind(p); In the unlikely case where H_SCM_BIND_MEM is returning H_OVERLAP once the unbinding has been done, the error would be silently processed. That sounds really unlikely, but should an error message be displayed in this particular case ? > + } > + > if (rc) > goto err; >