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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Wed, 26 Jun 2019 15:04:20 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5QE4JiQ58327158 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Jun 2019 14:04:19 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EAB8652050; Wed, 26 Jun 2019 14:04:18 +0000 (GMT) Received: from vajain21.in.ibm.com (unknown [9.109.195.183]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 4695552059; Wed, 26 Jun 2019 14:04:16 +0000 (GMT) From: Vaibhav Jain To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3 0/3] powerpc/papr_scm: Workaround for failure of drc bind after kexec Date: Wed, 26 Jun 2019 19:34:01 +0530 X-Mailer: git-send-email 2.21.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19062614-0012-0000-0000-0000032C975F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19062614-0013-0000-0000-00002165D1B5 Message-Id: <20190626140404.27448-1-vaibhav@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-26_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=792 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906260168 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: "Aneesh Kumar K . V" , Oliver O'Halloran , Vaibhav Jain , Laurent Dufour , David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Presently an error is returned in response to hcall H_SCM_BIND_MEM when a new kernel boots on lpar via kexec. This prevents papr_scm from registering drc memory regions with nvdimm. The error reported is of the form below: "papr_scm ibm,persistent-memory:ibm,pmemory@44100002: bind err: -68" On investigation it was revealed that phyp returns this error as previous kernel did not completely release bindings for drc scm-memory blocks and hence phyp rejected request for re-binding these block to lpar with error H_OVERLAP. Also support for a new H_SCM_UNBIND_ALL is recently added which is better suited for releasing all the bound scm-memory block from an lpar. So leveraging new hcall H_SCM_UNBIND_ALL, we can workaround H_OVERLAP issue during kexec by forcing an unbind of all drm scm-memory blocks and issuing H_SCM_BIND_MEM to re-bind the drc scm-memory blocks to lpar. This sequence will also be needed when a new kernel boot on lpar after previous kernel panicked and it never got an opportunity to call H_SCM_UNBIND_MEM/ALL. Hence this patch-set implements following changes to papr_scm module: * Update hvcall.h to include opcodes for new hcall H_SCM_UNBIND_ALL. * Update it to use H_SCM_UNBIND_ALL instead of H_SCM_UNBIND_MEM * In case hcall H_SCM_BIND_MEM fails with error H_OVERLAP, force H_SCM_UNBIND_ALL and retry the bind operation again. With the patch-set applied re-bind of drc scm-memory to lpar succeeds after a kexec to new kernel as illustrated below: # Old kernel $ sudo ndctl list -R [ { "dev":"region0", .... } ] # kexec to new kernel $ sudo kexec --initrd=... vmlinux ... ... I'm in purgatory ... papr_scm ibm,persistent-memory:ibm,pmemory@44100002: Un-binding and retrying ... # New kernel $ sudo ndctl list -R [ { "dev":"region0", .... } ] --- Change-log: v3: * Fixed a build warning reported by kbuild test robot. * Updated the hcall opcode from latest papr-scm specification. * Fixed a minor code comment & patch description as pointed out by Oliver. v2: * Addressed review comments from Oliver on v1 patchset. Vaibhav Jain (3): powerpc/pseries: Update SCM hcall op-codes in hvcall.h powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails arch/powerpc/include/asm/hvcall.h | 11 ++++-- arch/powerpc/platforms/pseries/papr_scm.c | 44 ++++++++++++++++++----- 2 files changed, 44 insertions(+), 11 deletions(-) -- 2.21.0