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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C1A63C5DF66 for ; Mon, 17 Aug 2026 09:15:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 37D246B0929; Mon, 17 Aug 2026 05:15:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 354346B092B; Mon, 17 Aug 2026 05:15:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 26A076B092C; Mon, 17 Aug 2026 05:15:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id E17556B0929 for ; Mon, 17 Aug 2026 05:15:44 -0400 (EDT) Received: from smtpin10.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 7AB8A160676 for ; Mon, 17 Aug 2026 09:15:44 +0000 (UTC) X-FDA: 85110203808.10.715A44F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf18.hostedemail.com (Postfix) with ESMTP id 943041C0005 for ; Mon, 17 Aug 2026 09:15:42 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=X2wo0EqG; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786958142; b=BUSmwGsOEcPZstckV+C5aBD/F2Z2VmqDJ+Vu/G4alzQEsyth0wITKNnPI3trkBQ7Lqf6bS I0mGsr0jrckWOwFt2oP/FC7IgGdPO9dW8A6d9ZRnvTIC6uqmDt7qrF2jFeQFSnDSdfvU/c wVWi8lbtYF/OarzWutaxU3r+I3QK8Q0= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=X2wo0EqG; spf=pass (imf18.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786958142; 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=n9jm7nE+72OxJlRILZ3KDGXzGVb6MqFq8JwjpfeAmYE=; b=dwAyl8QveibI2AHpPNA+AoNjbTrzsfEAurgQXsrns/fiiokDByP7s4cZST7O5/50kbeZc5 qehbKcHzTxJJXiY/qDt84KPWqATait3prOA8mzY4Li/iXRqGR4WDZFNcWdW0apx5AzGnRb M/DOGADABvww94zdvWHeO7gzdQtwzgU= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id AC40F41AB0; Mon, 17 Aug 2026 09:15:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6BA61F000E9; Mon, 17 Aug 2026 09:15:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786958141; bh=n9jm7nE+72OxJlRILZ3KDGXzGVb6MqFq8JwjpfeAmYE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=X2wo0EqGs5RjqnGB89rtFjzKK8w0JntqVFiM2OgPKQ2PRuF5REQNaZuYkKDJkhrhY I70NB75bFxsNlA+4hqOyNxYB9XKiHs3fi3hVBt7YIkVdjqu0+wYxWFySzi2gTETqGX 2qwjV8ylR/zdA0b/kyqwBVDEhcJZzSUsSEGH6sbmNepbEzv6q5/0sqrYcXzy62pJaz LGOVRJJmZx6aWyUbZupzgRfsr4pmEc8oy2D9nafip5whrbjOXhNNtTxgL1/yI9mQCB 0fOS/CNfCgB1n2fn/gOmN5OkrI7sfW5VtwPY8SFbUS4AoZqKl5OK8Ae4mduQLFG3y9 FAE9l3uICQSWA== Message-ID: <18529aed-9bb9-4771-9799-ba35fa0c657a@kernel.org> Date: Mon, 17 Aug 2026 11:15:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 20/41] KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes To: Ackerley Tng , aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, tabba@google.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , tarunsahu@google.com, Vlastimil Babka Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, Xiaoyao Li References: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@google.com> <20260807-gmem-inplace-conversion-v10-20-2fc18ee6d3ba@google.com> <82ded1ea-e0f6-48d9-8bcb-38a6bc5e9176@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 943041C0005 X-Stat-Signature: htt5mebo9f74bxa5qu1i848jthecpwnb X-HE-Tag: 1786958142-204803 X-HE-Meta: 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 znz5BQc8 VeD6JOVqHqiRxOO7vX9tSXXoZ2ce689yw+G1OXuVYAOR/Hb8jRrABGOUfwNYRaEwB/aUbKBZ5GD0X+2Rxw2LHVkBXfC0QM0Kjb59iqV6I5SbKon4gsVWP/s6GKtc3BmiVChOF7+1tUrHDnBVOgfDhsWmpYYoa6wic1BI/s82/sKFl0hssLkQ3AlRi7SvKMHNw3YdODcD5Vgfo+/2bUiNaOsy1cp826Nbppy4TToSPWoS+SU6eyKUPbdIPMBuALBYmQpxFWCz5cJ23tjUMbfzk5uuauNdEaHw7WKJ1PSgh3Pg9JQZcxKVhFxUGYg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/13/26 23:23, Ackerley Tng wrote: > "David Hildenbrand (Arm)" writes: > >> On 8/7/26 23:52, Ackerley Tng via B4 Relay wrote: >>> From: Ackerley Tng >>> >>> >>> [...snip...] >>> >>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig >>> index abb108886733a..2c3c22aeafa54 100644 >>> --- a/arch/x86/kvm/Kconfig >>> +++ b/arch/x86/kvm/Kconfig >>> @@ -81,13 +81,21 @@ config KVM_WERROR >>> If in doubt, say "N". >>> >>> config KVM_VM_MEMORY_ATTRIBUTES >>> - bool >>> + bool "Enable per-VM PRIVATE vs. SHARED attributes (for CoCo VMs)" >>> + depends on KVM_SW_PROTECTED_VM || KVM_INTEL_TDX || KVM_AMD_SEV >>> + help >>> + Enable support for tracking PRIVATE vs. SHARED memory using per-VM >>> + memory attributes. Using per-VM attributes is deprecated in favor of >>> + tracking PRIVATE state in guest_memfd. Select this if you need to run >>> + CoCo VMs using a VMM that doesn't support guest_memfd memory >>> + attributes. >>> + >>> + If unsure, say N. >> >> Hm, does that imply that a distribution that must support both, cannot ship a >> single kernel? >> > > Did you mean this as a documentation comment? Should the above read: No, I was trying to understand the impact :) IIUC, a distribution that would have to support both would simply enable CONFIG_KVM_VM_MEMORY_ATTRIBUTES, and the module parameter would have to be used to select the mode of operation. I guess that's good enough! > > help > Enable support for tracking PRIVATE vs. SHARED memory using per-VM > memory attributes. Using per-VM attributes is deprecated in favor of > tracking PRIVATE state in guest_memfd. Select this if you need to run > CoCo VMs using a VMM that doesn't support guest_memfd memory > - attributes. > + attributes. Select this to defer selection of where PRIVATE vs. SHARED > + attributes are tracked to KVM module load time, where > + gmem_in_place_conversion can be specified as a module parameter. > > If unsure, say N. > > I think we should do _without_ the above clarification since using VM > memory attributes for shared/private status is intended to be > deprecated. > > Is it fair to say distributions should not support both, and if they > _must_ support both, they need to read code to figure this out? Yeah, I don't think we need a doc update. -- Cheers, David