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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 9A697C25B78 for ; Mon, 27 May 2024 18:32:31 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sBf8R-000604-JX; Mon, 27 May 2024 14:31:51 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBf8G-0005yJ-RM for qemu-devel@nongnu.org; Mon, 27 May 2024 14:31:50 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sBf8E-00011j-CA for qemu-devel@nongnu.org; Mon, 27 May 2024 14:31:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1716834696; 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: in-reply-to:in-reply-to:references:references; bh=44xd8ACQgWoUiy/RUP62Kmq/A/Uh8J5UBRlIjIaeLc4=; b=JOChDXo8/53bNI6DMQCQcIOhdgRav7e0zi4mGBpQ0fU7Oy+HYD3EEB+HFYk9vBMLbg8/AN lEBziOueO06lc8gmEn0XDpUN2BIGVRsctisQzXUSFgvYqGzLaethIpBvbHbsG6Y7r2FExB jSorMxm6SiBBHVAz32tlH5DcYIf9Ch8= Received: from mail-oi1-f198.google.com (mail-oi1-f198.google.com [209.85.167.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-561-jKhznWeiPWe0YR_0zf3syA-1; Mon, 27 May 2024 14:31:34 -0400 X-MC-Unique: jKhznWeiPWe0YR_0zf3syA-1 Received: by mail-oi1-f198.google.com with SMTP id 5614622812f47-3c9b3ae3a5dso29353b6e.2 for ; Mon, 27 May 2024 11:31:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1716834694; x=1717439494; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=44xd8ACQgWoUiy/RUP62Kmq/A/Uh8J5UBRlIjIaeLc4=; b=CxRQMib//146S2+zDprfklmd3YI8sXS4sb9QHry0h0OXPKg4EnhvHNDOsR4dEuyz7/ sp7SRnMRVfSbYrFPFubR0RPFZUdVTpOg0yAYtvPZ0wXzvAOKKhsT3AmzJu0l59mT91Y0 EvYsygvf5T3mrfia9WMNqzR6lcjInUZGc7drep8DjmAWWak1mHD8Z5Iu8gU56BVqZLER E8BBiP/Qq24p5D5et5Jm06kooBVB1TyJ8D/ZHc8snGeeSnmgG1WgzBd4A18wKRIhpNMK UTNCAJMe+eq8ORsS0mT7DuTwq5QFuPbqWUIJmiyxrs8IjuwJloezyKU3lP1oSFB1hNCI yJBA== X-Gm-Message-State: AOJu0YwZGiuW/RFhr+ul32LNHLtbssIP01o6aSSWEmY8x683Ukj63Q1+ WZJrucZxsG2s4D4rngAoBkrKMq2Z+Niakaxawb4931IihPyEO/JxDneK7VPGbg1x4BQ2XwA+v6o 2hsf9qwjgvdyblK2awespQJW64k6xd9KE1IhDLqEt8PZQGj7psNaa X-Received: by 2002:a05:6358:281a:b0:192:47fd:8bf0 with SMTP id e5c5f4694b2df-197e5669578mr984304455d.3.1716834693647; Mon, 27 May 2024 11:31:33 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFuwbkJF+DNwhwWJcMLJY8q+liD7hQEmUni+2xcGApXF1g2R7Z51I4BeNKfqez5ss4CmKyjJw== X-Received: by 2002:a05:6358:281a:b0:192:47fd:8bf0 with SMTP id e5c5f4694b2df-197e5669578mr984301655d.3.1716834692907; Mon, 27 May 2024 11:31:32 -0700 (PDT) Received: from x1n (pool-99-254-121-117.cpe.net.cable.rogers.com. [99.254.121.117]) by smtp.gmail.com with ESMTPSA id af79cd13be357-794abcc0e58sm316274785a.40.2024.05.27.11.31.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 May 2024 11:31:32 -0700 (PDT) Date: Mon, 27 May 2024 14:31:30 -0400 From: Peter Xu To: Steve Sistare Cc: qemu-devel@nongnu.org, Fabiano Rosas , David Hildenbrand , Igor Mammedov , Eduardo Habkost , Marcel Apfelbaum , Philippe Mathieu-Daude , Paolo Bonzini , "Daniel P. Berrange" , Markus Armbruster Subject: Re: [PATCH V1 08/26] migration: vmstate_info_void_ptr Message-ID: References: <1714406135-451286-1-git-send-email-steven.sistare@oracle.com> <1714406135-451286-9-git-send-email-steven.sistare@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1714406135-451286-9-git-send-email-steven.sistare@oracle.com> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.034, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Apr 29, 2024 at 08:55:17AM -0700, Steve Sistare wrote: > Define VMSTATE_VOID_PTR so the value of a pointer (but not its target) > can be saved in the migration stream. This will be needed for CPR. > > Signed-off-by: Steve Sistare This is really tricky. >From a first glance, I don't think migrating a VA is valid at all for migration even if with exec.. and looks insane to me for a cross-process migration, which seems to be allowed to use as a generic VMSD helper.. as VA is the address space barrier for different processes and I think it normally even apply to generic execve(), and we're trying to jailbreak for some reason.. It definitely won't work for any generic migration as sizeof(void*) can be different afaict between hosts, e.g. 32bit -> 64bit migrations. Some description would be really helpful in this commit message, e.g. explain the users and why. Do we need to poison that for generic VMSD use (perhaps with prefixed underscores)? I think I'll need to read on the rest to tell.. Thanks, -- Peter Xu