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Wed, 30 Oct 2024 14:32:28 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E080820040; Wed, 30 Oct 2024 14:32:27 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6CF5E20043; Wed, 30 Oct 2024 14:32:27 +0000 (GMT) Received: from li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com (unknown [9.155.204.135]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 30 Oct 2024 14:32:27 +0000 (GMT) Date: Wed, 30 Oct 2024 15:32:26 +0100 From: Alexander Gordeev To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, virtualization@lists.linux.dev, linux-doc@vger.kernel.org, kvm@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , Thomas Huth , Cornelia Huck , Janosch Frank , Claudio Imbrenda , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Eric Farman , Andrew Morton , Jonathan Corbet , Mario Casquero Subject: Re: [PATCH v3 3/7] s390/physmem_info: query diag500(STORAGE LIMIT) to support QEMU/KVM memory devices Message-ID: References: <20241025141453.1210600-1-david@redhat.com> <20241025141453.1210600-4-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241025141453.1210600-4-david@redhat.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: o0oMqycScrBsgJn-Wm-yIyXZO4bLMyZD X-Proofpoint-ORIG-GUID: tkzhKRRM0rBtbKmnHezVCceiN8aV8C4d X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-15_01,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 mlxscore=0 malwarescore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 phishscore=0 impostorscore=0 mlxlogscore=779 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410300111 X-Stat-Signature: xcumpsu6x9j3rtm4nwd4kurb6uqbcn5s X-Rspamd-Queue-Id: 5F98F1C0022 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1730298705-551343 X-HE-Meta: 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 11jFPR6C fNrY0QV9lCL2sYHNuVij3gzfLBC5JOAq1f7mEoqcEc4aRKSJqnS026UiheugIQvaUTuvN8928yx0m360pUtyQ9h/PaDtsh5Kw9RIGXAeOHwiVYePC9oEV1HeVBoTIV/+Fnk+LPqd3RSuP+idW1b6fnDFAP/l06utWGmL1bJ+EQ0QZ5VgC6BvtyCKPYREp+KRM7QnD/jPwGnvTfQiMH1G0tP+l6UFoT5qtsl0ZSLPpcqwkapnUEbDQO9xu8oyzaz8vZ7j/GVosP9iosVRrzK/IHJn1FdOgMG+Lz/IoabEXa4WTr7UKPxDx0tb+HbihhouJLRybV69+pRIvBmQ= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 25, 2024 at 04:14:48PM +0200, David Hildenbrand wrote: > To support memory devices under QEMU/KVM, such as virtio-mem, > we have to prepare our kernel virtual address space accordingly and > have to know the highest possible physical memory address we might see > later: the storage limit. The good old SCLP interface is not suitable for > this use case. > > In particular, memory owned by memory devices has no relationship to > storage increments, it is always detected using the device driver, and > unaware OSes (no driver) must never try making use of that memory. > Consequently this memory is located outside of the "maximum storage > increment"-indicated memory range. > > Let's use our new diag500 STORAGE_LIMIT subcode to query this storage > limit that can exceed the "maximum storage increment", and use the > existing interfaces (i.e., SCLP) to obtain information about the initial > memory that is not owned+managed by memory devices. > > If a hypervisor does not support such memory devices, the address exposed > through diag500 STORAGE_LIMIT will correspond to the maximum storage > increment exposed through SCLP. > > To teach kdump on s390 to include memory owned by memory devices, there > will be ways to query the relevant memory ranges from the device via a > driver running in special kdump mode (like virtio-mem already implements > to filter /proc/vmcore access so we don't end up reading from unplugged > device blocks). > > Update setup_ident_map_size(), to clarify that there can be more than > just online and standby memory. > > Tested-by: Mario Casquero > Signed-off-by: David Hildenbrand > --- > arch/s390/boot/physmem_info.c | 47 +++++++++++++++++++++++++++- > arch/s390/boot/startup.c | 7 +++-- > arch/s390/include/asm/physmem_info.h | 3 ++ > 3 files changed, 54 insertions(+), 3 deletions(-) Reviewed-by: Alexander Gordeev