From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCFBEC433DF for ; Fri, 3 Jul 2020 09:38:02 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 98EAA2084C for ; Fri, 3 Jul 2020 09:38:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ern1VgmU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 98EAA2084C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35688 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jrI8v-00037b-T9 for qemu-devel@archiver.kernel.org; Fri, 03 Jul 2020 05:38:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42524) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jrI4B-000271-Ea for qemu-devel@nongnu.org; Fri, 03 Jul 2020 05:33:07 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:33979 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jrI3y-0003fF-7T for qemu-devel@nongnu.org; Fri, 03 Jul 2020 05:33:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593768773; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=/h8hSh1DauZ6Ru4bBBqPc6jTYPCjb2A85Ri3QPbmLDs=; b=Ern1VgmUcoK7T2KWv6gVoubA7JZkAT9N0xxmamrQy5+VDIABxP0nyKNITMwSR9pD64Mm2D lpS0lf6c6USCeBZ0oZKmoFT9VCXqQCKj1ZJo2wat8PCyWcaqM1AbqAiPsk5ngxygGpdoeA hruVDqku5vgU1ZNTZykLzIrg/Q7Q3tU= 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-201-9Xfv5SIIPOGir0mhCtCbHg-1; Fri, 03 Jul 2020 05:32:51 -0400 X-MC-Unique: 9Xfv5SIIPOGir0mhCtCbHg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 55B0718A8249; Fri, 3 Jul 2020 09:32:50 +0000 (UTC) Received: from [10.36.114.0] (ovpn-114-0.ams2.redhat.com [10.36.114.0]) by smtp.corp.redhat.com (Postfix) with ESMTP id C5CF45C221; Fri, 3 Jul 2020 09:32:45 +0000 (UTC) Subject: Re: [PULL 13/41] virtio-mem: Paravirtualized memory hot(un)plug From: David Hildenbrand To: "Michael S. Tsirkin" , qemu-devel@nongnu.org References: <20200703090252.368694-1-mst@redhat.com> <20200703090252.368694-14-mst@redhat.com> <3691367f-9b31-dfa2-f180-823b1f080c09@redhat.com> Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <2d233963-effc-5238-8125-c56dc6d93700@redhat.com> Date: Fri, 3 Jul 2020 11:32:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <3691367f-9b31-dfa2-f180-823b1f080c09@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=david@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/03 01:34:15 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Igor Mammedov , Markus Armbruster , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 03.07.20 11:18, David Hildenbrand wrote: > On 03.07.20 11:04, Michael S. Tsirkin wrote: >> From: David Hildenbrand >> >> This is the very basic/initial version of virtio-mem. An introduction to >> virtio-mem can be found in the Linux kernel driver [1]. While it can be >> used in the current state for hotplug of a smaller amount of memory, it >> will heavily benefit from resizeable memory regions in the future. >> >> Each virtio-mem device manages a memory region (provided via a memory >> backend). After requested by the hypervisor ("requested-size"), the >> guest can try to plug/unplug blocks of memory within that region, in order >> to reach the requested size. Initially, and after a reboot, all memory is >> unplugged (except in special cases - reboot during postcopy). >> >> The guest may only try to plug/unplug blocks of memory within the usable >> region size. The usable region size is a little bigger than the >> requested size, to give the device driver some flexibility. The usable >> region size will only grow, except on reboots or when all memory is >> requested to get unplugged. The guest can never plug more memory than >> requested. Unplugged memory will get zapped/discarded, similar to in a >> balloon device. >> >> The block size is variable, however, it is always chosen in a way such that >> THP splits are avoided (e.g., 2MB). The state of each block >> (plugged/unplugged) is tracked in a bitmap. >> >> As virtio-mem devices (e.g., virtio-mem-pci) will be memory devices, we now >> expose "VirtioMEMDeviceInfo" via "query-memory-devices". >> >> -------------------------------------------------------------------------- >> >> There are two important follow-up items that are in the works: >> 1. Resizeable memory regions: Use resizeable allocations/RAM blocks to >> grow/shrink along with the usable region size. This avoids creating >> initially very big VMAs, RAM blocks, and KVM slots. >> 2. Protection of unplugged memory: Make sure the gust cannot actually >> make use of unplugged memory. >> >> Other follow-up items that are in the works: >> 1. Exclude unplugged memory during migration (via precopy notifier). >> 2. Handle remapping of memory. >> 3. Support for other architectures. >> >> -------------------------------------------------------------------------- >> >> Example usage (virtio-mem-pci is introduced in follow-up patches): >> >> Start QEMU with two virtio-mem devices (one per NUMA node): >> $ qemu-system-x86_64 -m 4G,maxmem=20G \ >> -smp sockets=2,cores=2 \ >> -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 \ >> [...] >> -object memory-backend-ram,id=mem0,size=8G \ >> -device virtio-mem-pci,id=vm0,memdev=mem0,node=0,requested-size=0M \ >> -object memory-backend-ram,id=mem1,size=8G \ >> -device virtio-mem-pci,id=vm1,memdev=mem1,node=1,requested-size=1G >> >> Query the configuration: >> (qemu) info memory-devices >> Memory device [virtio-mem]: "vm0" >> memaddr: 0x140000000 >> node: 0 >> requested-size: 0 >> size: 0 >> max-size: 8589934592 >> block-size: 2097152 >> memdev: /objects/mem0 >> Memory device [virtio-mem]: "vm1" >> memaddr: 0x340000000 >> node: 1 >> requested-size: 1073741824 >> size: 1073741824 >> max-size: 8589934592 >> block-size: 2097152 >> memdev: /objects/mem1 >> >> Add some memory to node 0: >> (qemu) qom-set vm0 requested-size 500M >> >> Remove some memory from node 1: >> (qemu) qom-set vm1 requested-size 200M >> >> Query the configuration again: >> (qemu) info memory-devices >> Memory device [virtio-mem]: "vm0" >> memaddr: 0x140000000 >> node: 0 >> requested-size: 524288000 >> size: 524288000 >> max-size: 8589934592 >> block-size: 2097152 >> memdev: /objects/mem0 >> Memory device [virtio-mem]: "vm1" >> memaddr: 0x340000000 >> node: 1 >> requested-size: 209715200 >> size: 209715200 >> max-size: 8589934592 >> block-size: 2097152 >> memdev: /objects/mem1 >> >> [1] https://lkml.kernel.org/r/20200311171422.10484-1-david@redhat.com >> >> Cc: "Michael S. Tsirkin" >> Cc: Eric Blake >> Cc: Markus Armbruster >> Cc: "Dr. David Alan Gilbert" >> Cc: Igor Mammedov >> Signed-off-by: David Hildenbrand >> Message-Id: <20200626072248.78761-11-david@redhat.com> >> Reviewed-by: Michael S. Tsirkin >> Signed-off-by: Michael S. Tsirkin >> --- >> qapi/misc.json | 39 +- >> include/hw/virtio/virtio-mem.h | 78 ++++ >> hw/virtio/virtio-mem.c | 724 +++++++++++++++++++++++++++++++++ >> hw/virtio/Kconfig | 11 + >> hw/virtio/Makefile.objs | 1 + >> 5 files changed, 852 insertions(+), 1 deletion(-) >> create mode 100644 include/hw/virtio/virtio-mem.h >> create mode 100644 hw/virtio/virtio-mem.c >> >> diff --git a/qapi/misc.json b/qapi/misc.json >> index a5a0beb902..65ca3edf32 100644 >> --- a/qapi/misc.json >> +++ b/qapi/misc.json >> @@ -1356,19 +1356,56 @@ >> } >> } >> >> +## >> +# @VirtioMEMDeviceInfo: >> +# >> +# VirtioMEMDevice state information >> +# >> +# @id: device's ID >> +# >> +# @memaddr: physical address in memory, where device is mapped >> +# >> +# @requested-size: the user requested size of the device >> +# >> +# @size: the (current) size of memory that the device provides >> +# >> +# @max-size: the maximum size of memory that the device can provide >> +# >> +# @block-size: the block size of memory that the device provides >> +# >> +# @node: NUMA node number where device is assigned to >> +# >> +# @memdev: memory backend linked with the region >> +# >> +# Since: 5.1 >> +## >> +{ 'struct': 'VirtioMEMDeviceInfo', >> + 'data': { '*id': 'str', >> + 'memaddr': 'size', >> + 'requested-size': 'size', >> + 'size': 'size', >> + 'max-size': 'size', >> + 'block-size': 'size', >> + 'node': 'int', >> + 'memdev': 'str' >> + } >> +} >> + >> ## >> # @MemoryDeviceInfo: >> # >> # Union containing information about a memory device >> # >> # nvdimm is included since 2.12. virtio-pmem is included since 4.1. >> +# virtio-mem is included since 5.1. >> # >> # Since: 2.1 >> ## >> { 'union': 'MemoryDeviceInfo', >> 'data': { 'dimm': 'PCDIMMDeviceInfo', >> 'nvdimm': 'PCDIMMDeviceInfo', >> - 'virtio-pmem': 'VirtioPMEMDeviceInfo' >> + 'virtio-pmem': 'VirtioPMEMDeviceInfo', >> + 'virtio-mem': 'VirtioMEMDeviceInfo' >> } >> } >> >> diff --git a/include/hw/virtio/virtio-mem.h b/include/hw/virtio/virtio-mem.h >> new file mode 100644 >> index 0000000000..6981096f7c >> --- /dev/null >> +++ b/include/hw/virtio/virtio-mem.h >> @@ -0,0 +1,78 @@ >> +/* >> + * Virtio MEM device >> + * >> + * Copyright (C) 2020 Red Hat, Inc. >> + * >> + * Authors: >> + * David Hildenbrand >> + * >> + * This work is licensed under the terms of the GNU GPL, version 2. >> + * See the COPYING file in the top-level directory. >> + */ >> + >> +#ifndef HW_VIRTIO_MEM_H >> +#define HW_VIRTIO_MEM_H >> + >> +#include "standard-headers/linux/virtio_mem.h" >> +#include "hw/virtio/virtio.h" >> +#include "qapi/qapi-types-misc.h" >> +#include "sysemu/hostmem.h" >> + >> +#define TYPE_VIRTIO_MEM "virtio-mem" >> + >> +#define VIRTIO_MEM(obj) \ >> + OBJECT_CHECK(VirtIOMEM, (obj), TYPE_VIRTIO_MEM) >> +#define VIRTIO_MEM_CLASS(oc) \ >> + OBJECT_CLASS_CHECK(VirtIOMEMClass, (oc), TYPE_VIRTIO_MEM) >> +#define VIRTIO_MEM_GET_CLASS(obj) \ >> + OBJECT_GET_CLASS(VirtIOMEMClass, (obj), TYPE_VIRTIO_MEM) >> + >> +#define VIRTIO_MEM_MEMDEV_PROP "memdev" >> +#define VIRTIO_MEM_NODE_PROP "node" >> +#define VIRTIO_MEM_SIZE_PROP "size" >> +#define VIRTIO_MEM_REQUESTED_SIZE_PROP "requested-size" >> +#define VIRTIO_MEM_BLOCK_SIZE_PROP "block-size" >> +#define VIRTIO_MEM_ADDR_PROP "memaddr" >> + >> +typedef struct VirtIOMEM { >> + VirtIODevice parent_obj; >> + >> + /* guest -> host request queue */ >> + VirtQueue *vq; >> + >> + /* bitmap used to track unplugged memory */ >> + int32_t bitmap_size; >> + unsigned long *bitmap; >> + >> + /* assigned memory backend and memory region */ >> + HostMemoryBackend *memdev; >> + >> + /* NUMA node */ >> + uint32_t node; >> + >> + /* assigned address of the region in guest physical memory */ >> + uint64_t addr; >> + >> + /* usable region size (<= region_size) */ >> + uint64_t usable_region_size; >> + >> + /* actual size (how much the guest plugged) */ >> + uint64_t size; >> + >> + /* requested size */ >> + uint64_t requested_size; >> + >> + /* block size and alignment */ >> + uint64_t block_size; >> +} VirtIOMEM; >> + >> +typedef struct VirtIOMEMClass { >> + /* private */ >> + VirtIODevice parent; >> + >> + /* public */ >> + void (*fill_device_info)(const VirtIOMEM *vmen, VirtioMEMDeviceInfo *vi); >> + MemoryRegion *(*get_memory_region)(VirtIOMEM *vmem, Error **errp); >> +} VirtIOMEMClass; >> + >> +#endif >> diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c >> new file mode 100644 >> index 0000000000..d8a0c974d3 >> --- /dev/null >> +++ b/hw/virtio/virtio-mem.c >> @@ -0,0 +1,724 @@ >> +/* >> + * Virtio MEM device >> + * >> + * Copyright (C) 2020 Red Hat, Inc. >> + * >> + * Authors: >> + * David Hildenbrand >> + * >> + * This work is licensed under the terms of the GNU GPL, version 2. >> + * See the COPYING file in the top-level directory. >> + */ >> + >> +#include "qemu/osdep.h" >> +#include "qemu-common.h" >> +#include "qemu/iov.h" >> +#include "qemu/cutils.h" >> +#include "qemu/error-report.h" >> +#include "qemu/units.h" >> +#include "sysemu/numa.h" >> +#include "sysemu/sysemu.h" >> +#include "sysemu/reset.h" >> +#include "hw/virtio/virtio.h" >> +#include "hw/virtio/virtio-bus.h" >> +#include "hw/virtio/virtio-access.h" >> +#include "hw/virtio/virtio-mem.h" >> +#include "qapi/error.h" >> +#include "qapi/visitor.h" >> +#include "exec/ram_addr.h" >> +#include "migration/misc.h" >> +#include "hw/boards.h" >> +#include "hw/qdev-properties.h" >> +#include "config-devices.h" >> + >> +/* >> + * Use QEMU_VMALLOC_ALIGN, so no THP will have to be split when unplugging >> + * memory (e.g., 2MB on x86_64). >> + */ >> +#define VIRTIO_MEM_MIN_BLOCK_SIZE QEMU_VMALLOC_ALIGN >> +/* >> + * Size the usable region bigger than the requested size if possible. Esp. >> + * Linux guests will only add (aligned) memory blocks in case they fully >> + * fit into the usable region, but plug+online only a subset of the pages. >> + * The memory block size corresponds mostly to the section size. >> + * >> + * This allows e.g., to add 20MB with a section size of 128MB on x86_64, and >> + * a section size of 1GB on arm64 (as long as the start address is properly >> + * aligned, similar to ordinary DIMMs). >> + * >> + * We can change this at any time and maybe even make it configurable if >> + * necessary (as the section size can change). But it's more likely that the >> + * section size will rather get smaller and not bigger over time. >> + */ >> +#if defined(__x86_64__) >> +#define VIRTIO_MEM_USABLE_EXTENT (2 * (128 * MiB)) > > I just did a cross-compile on s390x and noticed that this should be > guarded by defined(TARGET_X86_64) (it's target dependent). #if defined(TARGET_X86_64) || defined(TARGET_I386) to be precise. -- Thanks, David / dhildenb