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Tsirkin" , Jason Wang , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Andrew Morton , Jonathan Corbet Subject: Re: [PATCH v2 0/7] virtio-mem: s390 support Message-ID: <20241014185659.10447-H-hca@linux.ibm.com> References: <20241014144622.876731-1-david@redhat.com> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241014144622.876731-1-david@redhat.com> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 6uFDGy-zlz1QTPEIrQYEpX_XW_Pumpmi X-Proofpoint-ORIG-GUID: Or6XZdCkJUWtzOmMfibubfT24pmJTuiG 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=2024-10-14_12,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 bulkscore=0 suspectscore=0 adultscore=0 priorityscore=1501 impostorscore=0 mlxlogscore=999 phishscore=0 clxscore=1015 malwarescore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410140135 On Mon, Oct 14, 2024 at 04:46:12PM +0200, David Hildenbrand wrote: > Let's finally add s390 support for virtio-mem; my last RFC was sent > 4 years ago, and a lot changed in the meantime. > > The latest QEMU series is available at [1], which contains some more > details and a usage example on s390 (last patch). > > There is not too much in here: The biggest part is querying a new diag(500) > STORAGE_LIMIT hypercall to obtain the proper "max_physmem_end". > > The last two patches are not strictly required but certainly nice-to-have. > > Note that -- in contrast to standby memory -- virtio-mem memory must be > configured to be automatically onlined as soon as hotplugged. The easiest > approach is using the "memhp_default_state=" kernel parameter or by using > proper udev rules. More details can be found at [2]. > > I have reviving+upstreaming a systemd service to handle configuring > that on my todo list, but for some reason I keep getting distracted ... > > I tested various things, including: > * Various memory hotplug/hotunplug combinations > * Device hotplug/hotunplug > * /proc/iomem output > * reboot > * kexec > * kdump: make sure we don't hotplug memory > > One remaining work item is kdump support for virtio-mem memory. This will > be sent out separately once initial support landed. Besides the open kdump question, which I think is quite important, how is this supposed to go upstream? This could go via s390, however in any case this needs reviews and/or Acks from kvm folks.