From patchwork Wed Apr 29 16:08:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11517819 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0E4EE112C for ; Wed, 29 Apr 2020 16:08:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5CCA21BE5 for ; Wed, 29 Apr 2020 16:08:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QZPrrd8z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726519AbgD2QIg (ORCPT ); Wed, 29 Apr 2020 12:08:36 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:29774 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726476AbgD2QIf (ORCPT ); Wed, 29 Apr 2020 12:08:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588176513; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=RqcnavPFirGVOTXHhjY5q5DM9FLFgis6bxz7RvWdVJE=; b=QZPrrd8zNNebgZXnzhIAYA2aP84wbXzXTC4SfYYO6rv5ju2/aeWwsXYRoUwkzVKNDRurdJ YxExOEc0hr+rJQkkFgPUr+ph31cSB3GXU2c+/TgswYJtJaAdE4hLZ9KBhaCdgY7s0ei/vk ZW/gaMqEpwiuaxXcYVMdRLbEU5DvYnE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-480-F36vCcGRMVu93iH7TXheIg-1; Wed, 29 Apr 2020 12:08:26 -0400 X-MC-Unique: F36vCcGRMVu93iH7TXheIg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E4E0C1895A28; Wed, 29 Apr 2020 16:08:21 +0000 (UTC) Received: from t480s.redhat.com (ovpn-114-55.ams2.redhat.com [10.36.114.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id BAF7C605FB; Wed, 29 Apr 2020 16:08:07 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, xen-devel@lists.xenproject.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , David Hildenbrand , Baoquan He , Benjamin Herrenschmidt , Boris Ostrovsky , Christian Borntraeger , Dan Williams , Dave Jiang , Eric Biederman , Greg Kroah-Hartman , Haiyang Zhang , Heiko Carstens , Jason Wang , Juergen Gross , "K. Y. Srinivasan" , Len Brown , Leonardo Bras , Michael Ellerman , Michal Hocko , Nathan Lynch , Oscar Salvador , Pankaj Gupta , Paul Mackerras , Pingfan Liu , "Rafael J. Wysocki" , Stefano Stabellini , Stephen Hemminger , Thomas Gleixner , Vasily Gorbik , Vishal Verma , Wei Liu , Wei Yang Subject: [PATCH v1 0/3] mm/memory_hotplug: Make virtio-mem play nicely with kexec-tools Date: Wed, 29 Apr 2020 18:08:00 +0200 Message-Id: <20200429160803.109056-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org This series is based on [1]: [PATCH v2 00/10] virtio-mem: paravirtualized memory That will hopefull get picked up soon, rebased to -next. The following patches were reverted from -next [2]: [PATCH 0/3] kexec/memory_hotplug: Prevent removal and accidental use As discussed in that thread, they should be reverted from -next already. In theory, if people agree, we could take the first two patches via the -mm tree now and the last (virtio-mem) patch via MST's tree once picking up virtio-mem. No strong feelings. Memory added by virtio-mem is special and might contain logical holes, especially after memory unplug, but also when adding memory in sub-section size. While memory in these holes can usually be read, that memory should not be touched. virtio-mem managed device memory is never exposed via any firmware memmap (esp., e820). The device driver will request to plug memory from the hypervisor and add it to Linux. On a cold start, all memory is unplugged, and the guest driver will first request to plug memory from the hypervisor, to then add it to Linux. After a reboot, all memory will get unplugged (except in rare, special cases). In case the device driver comes up and detects that some memory is still plugged after a reboot, it will manually request to unplug all memory from the hypervisor first - to then request to plug memory from the hypervisor and add to Linux. This is essentially a defragmentation step, where all logical holes are removed. As the device driver is responsible for detecting, adding and managing that memory, also kexec should treat it like that. It is special. We need a way to teach kexec-tools to not add that memory to the fixed-up firmware memmap, to not place kexec images onto this memory, but still allow kdump to dump it. Add a flag to tell memory hotplug code to not create /sys/firmware/memmap entries and to indicate it via "System RAM (driver managed)" in /proc/iomem. Before this series, kexec_file_load() already did the right thing (for virtio-mem) by not adding that memory to the fixed-up firmware memmap and letting the device driver handle it. With this series, also kexec_load() - which relies on user space to provide a fixed up firmware memmap - does the right thing with virtio-mem memory. When the virtio-mem device driver(s) come up, they will request to unplug all memory from the hypervisor first (esp. defragment), to then request to plug consecutive memory ranges from the hypervisor, and add them to Linux - just like on a reboot where we still have memory plugged. [1] https://lore.kernel.org/r/20200311171422.10484-1-david@redhat.com/ [2] https://lore.kernel.org/r/20200326180730.4754-1-james.morse@arm.com David Hildenbrand (3): mm/memory_hotplug: Prepare passing flags to add_memory() and friends mm/memory_hotplug: Introduce MHP_DRIVER_MANAGED virtio-mem: Add memory with MHP_DRIVER_MANAGED arch/powerpc/platforms/powernv/memtrace.c | 2 +- .../platforms/pseries/hotplug-memory.c | 2 +- drivers/acpi/acpi_memhotplug.c | 2 +- drivers/base/memory.c | 2 +- drivers/dax/kmem.c | 2 +- drivers/hv/hv_balloon.c | 2 +- drivers/s390/char/sclp_cmd.c | 2 +- drivers/virtio/virtio_mem.c | 3 +- drivers/xen/balloon.c | 2 +- include/linux/memory_hotplug.h | 15 +++++++-- mm/memory_hotplug.c | 31 +++++++++++++------ 11 files changed, 44 insertions(+), 21 deletions(-)