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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6CCDEEE57DF for ; Mon, 11 Sep 2023 08:09:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CE78C6B0183; Mon, 11 Sep 2023 04:09:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C70956B0184; Mon, 11 Sep 2023 04:09:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AE9BC6B0185; Mon, 11 Sep 2023 04:09:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 9CED46B0183 for ; Mon, 11 Sep 2023 04:09:52 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 75189C092D for ; Mon, 11 Sep 2023 08:09:52 +0000 (UTC) X-FDA: 81223593024.01.3B34D40 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf18.hostedemail.com (Postfix) with ESMTP id 4075F1C001B for ; Mon, 11 Sep 2023 08:09:50 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=KWIIgAC1; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf18.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1694419790; h=from:from:sender: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:dkim-signature; bh=OE5jHWIoTi0oDDOVSbCQAUkm2GG93rVvkvjC/9s+zDo=; b=sg6Oxvuk1nO8zH3VR9Qd5QHwmFYgx5aFz9YUhHXNGoI/wmzKLO6AW0G/sy/+Jmdu9otClZ Nuu7QFS6LWWZcQ0tTgBO7EbRQK9tDPdmjo+yy9Ip24QNABCHjnNNHVZfnZSJcZS1CfXnNx Iwirfd1O1SFzq9ws9ggLxAk68L/S+KQ= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=KWIIgAC1; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf18.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1694419790; a=rsa-sha256; cv=none; b=4gIERxglX2n60rYl3Nwy2qtMuy2Xi0cpMNOC/0CkDgdyJWhM94WvFyePYW/+gjn1kMKTML E3FChsQ5rRG4SICSTM0FBIM0IPqZlXNLwvdVDiKte94iLdKiiJpChn7Y3Ehtl20/G33yf8 unojVEbNzRf6AgSIzJCFsmlNYMwRH/U= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1694419789; 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; bh=OE5jHWIoTi0oDDOVSbCQAUkm2GG93rVvkvjC/9s+zDo=; b=KWIIgAC1S2/3x63tiausX3L2lAowr/B/rsJgovCKBRAFS2tz59MwWN+p0IBM2cE0LKXu4l 0LDUjPJTgpJts/czq4frOiwBT6NnluTk/RFXskktkK+swd9jgI8UYlCnN/LvaDOVnfRbao fmZNKyGWxYGBbTHFZENOCU6roE+s1eM= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-663-HvGgn1JiOz2EM0Bp17sWlQ-1; Mon, 11 Sep 2023 04:09:48 -0400 X-MC-Unique: HvGgn1JiOz2EM0Bp17sWlQ-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-402ccac9b1eso30432605e9.0 for ; Mon, 11 Sep 2023 01:09:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694419787; x=1695024587; h=content-transfer-encoding:in-reply-to:organization:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=OE5jHWIoTi0oDDOVSbCQAUkm2GG93rVvkvjC/9s+zDo=; b=rhnztVLqQ5mbQ2sm5UZnSIxWWcgjpLom98aFBaiAj4wSoj1ley+ylM4ZaBRiCT7kgy NLuYA/j2V343dPHKbQ40XTVcU2Do9OVMzmTox/SSDhfbWgHcP9d767ZGyGivjL0EKBDX hrkiVRQKnQML1l5FD0cLPev05opkdS4L3Np4XrQx/7kxlrkBz4iFP8UKrP7CvXIvwooC 1OY4pWa1NJqHPcA5DVBphlLUUjRG5OK9S/uRbHLoIUySpSXgLp2Yo+Bn/DxXaw6TIFHT sGkS54Ii9qtd9y1+reNWuoW/4TINeWDDVR3oXlA+MBJjxeTrhN8WnQsZx/o9G8tkQP+U rkWg== X-Gm-Message-State: AOJu0Yz0wwu3n3nwHQF1QNk0UyJ/UBCUZYLN3OufBL45v/NU+rL7Vjko v+uEyK7vMqV3xd8U0mtK7xsPg1UDMK+YmKKxzcdj2cSmtzob/V0phFxskHAePrlYdbqmvyD0434 inTbRSB3p0zs= X-Received: by 2002:a7b:cd97:0:b0:3f6:9634:c8d6 with SMTP id y23-20020a7bcd97000000b003f69634c8d6mr7756888wmj.18.1694419786953; Mon, 11 Sep 2023 01:09:46 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEP/fXfkIDU6FsZ0+ujLPL6eiYP/U8dRfUXceL70QbvmQvHtk7DVWUJv4/1OPaMnnx/ifbxFQ== X-Received: by 2002:a7b:cd97:0:b0:3f6:9634:c8d6 with SMTP id y23-20020a7bcd97000000b003f69634c8d6mr7756871wmj.18.1694419786499; Mon, 11 Sep 2023 01:09:46 -0700 (PDT) Received: from ?IPV6:2003:cb:c743:5500:a9bd:94ab:74e9:782f? (p200300cbc7435500a9bd94ab74e9782f.dip0.t-ipconnect.de. [2003:cb:c743:5500:a9bd:94ab:74e9:782f]) by smtp.gmail.com with ESMTPSA id gw18-20020a05600c851200b004030c778396sm3452549wmb.4.2023.09.11.01.09.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Sep 2023 01:09:46 -0700 (PDT) Message-ID: Date: Mon, 11 Sep 2023 10:09:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH 3/3] /dev/mem: Do not map unaccepted memory To: Dave Hansen , "Kirill A. Shutemov" Cc: Adrian Hunter , Borislav Petkov , Andrew Morton , Vlastimil Babka , Mike Rapoport , Lorenzo Stoakes , Tom Lendacky , Baoquan He , Vivek Goyal , Dave Young , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, kexec@lists.infradead.org References: <20230906073902.4229-1-adrian.hunter@intel.com> <20230906073902.4229-4-adrian.hunter@intel.com> <9ffb7a3b-cf20-617a-e4f1-8a6a8a2c5972@intel.com> <20230907142510.vcj57cvnewqt4m37@box.shutemov.name> <7a50d04f-63ee-a901-6f39-7d341e423a77@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <7a50d04f-63ee-a901-6f39-7d341e423a77@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4075F1C001B X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: y6rybiip944gmoxsqg59w6i4fdeg59yg X-HE-Tag: 1694419790-521477 X-HE-Meta: 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 02Np3YSI eAttqK69XjYnijMEBN9mq14Gk1iaF1L58TvXCZzAXglooiIIbnLdlM1QeNDnugxFolS+KDbnxETDd1PdI7CbXw3Zq4TXvKcc+O9cynxy2Nmttw2M1VZNm1c1v2L4k5b7RN6J1K6LXjk3zCO2UVeUPO600/AhpYjxIC04r/c+poDTr/7fn/hS5g0KO3pU3zBY93n4S3bhxiYLI26AmRzxrDERExqTK/NDJyaAe4HHSUpGCg/IxcKvFHwyRoq4DbR2r9dvmEJV5JjwB4jIVyAob+xEoJTQRlOmRFkRzMFfJPFzCL0YxADsbg4Qv836yDOhhIdGZWrSXeQ4CxIJcXKQgquhM0ocf7/Mw4U1unP3QAqmkrV3d+1uCUM5cGubGi/Yen82l 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: On 07.09.23 16:46, Dave Hansen wrote: > On 9/7/23 07:25, Kirill A. Shutemov wrote: >> On Thu, Sep 07, 2023 at 07:15:21AM -0700, Dave Hansen wrote: >>> On 9/6/23 00:39, Adrian Hunter wrote: >>>> Support for unaccepted memory was added recently, refer commit >>>> dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby >>>> a virtual machine may need to accept memory before it can be used. >>>> >>>> Do not map unaccepted memory because it can cause the guest to fail. >>> Doesn't /dev/mem already provide a billion ways for someone to shoot >>> themselves in the foot? TDX seems to have added the 1,000,000,001st. >>> Is this really worth patching? >> Is it better to let TD die silently? I don't think so. > > First, let's take a look at all of the distro kernels that folks will > run under TDX. Do they have STRICT_DEVMEM set? For virtio-mem, we do config VIRTIO_MEM ... depends on EXCLUSIVE_SYSTEM_RAM Which in turn: config EXCLUSIVE_SYSTEM_RAM ... depends on !DEVMEM || STRICT_DEVMEM Not supported on all archs, but at least on RHEL9 on x86_64 and aarch64. So, making unaccepted memory similarly depend on "!DEVMEM || STRICT_DEVMEM" does not sound too far off ... -- Cheers, David / dhildenb