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 CA10FC83F1B for ; Wed, 16 Jul 2025 10:31:58 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 673C78D0002; Wed, 16 Jul 2025 06:31:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 624B78D0001; Wed, 16 Jul 2025 06:31:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5137A8D0002; Wed, 16 Jul 2025 06:31:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 3FA9B8D0001 for ; Wed, 16 Jul 2025 06:31:58 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A71211D9D68 for ; Wed, 16 Jul 2025 10:31:57 +0000 (UTC) X-FDA: 83669762274.20.FE4ED8D Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf28.hostedemail.com (Postfix) with ESMTP id 74C70C0006 for ; Wed, 16 Jul 2025 10:31:55 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=TFGoDRvt; spf=pass (imf28.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1752661915; 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=QcznUuIcwG4nXt+4JQ0HOO8HtlWuNhZcwm0Vh8nXhEs=; b=TCIYu3ZKyxGNM6z0EXyjeE2tbMAFaqxH0cZDmkNwpXC2Tu6SaGJKLFogLUPCg+JTbjDWNF t7F61Cf0Yim3Dqm1mF6XbwOO2glx2o5Vr6pL36mRSUPAelQWxgkkg0h3nTgpvApaWz5511 0bKNLXbXwyGw+D43keSQcMnHnDVjulI= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752661915; a=rsa-sha256; cv=none; b=Oi8lZKW0ZxU1T6TuhOJfFRsOvkICUsv0fEUhgd+Bzpd+Cth81pNz16nADFGFudk3MFI5SQ WI49IUgGEBLU7fJ2T0ik3rvnYoBKky8B6lQWKQdHAELmVp7K3611hvWOhiGytbBh7X2R4r AMqO7yBsgiOIhDVCeeqc8i5kIAO/OvY= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=TFGoDRvt; spf=pass (imf28.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=quarantine) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752661914; 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=QcznUuIcwG4nXt+4JQ0HOO8HtlWuNhZcwm0Vh8nXhEs=; b=TFGoDRvtwiqPEk+T0mxYBNpbswSD3IO016+7Y+0SgMCiB+CH28j9qacr5de02yFVQCTxB0 yo4EB1+2uwELGyM5l4B1L1ZhO3oNferiPHXZzPudNPYP8No3qAqgFPBLF+8MEWDndJ2lT/ yjvRJ1zYSHj4Fs6oeg5SkToLWd4nP80= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-59-R-9FZXHDOiakLybY74ZfmA-1; Wed, 16 Jul 2025 06:31:53 -0400 X-MC-Unique: R-9FZXHDOiakLybY74ZfmA-1 X-Mimecast-MFC-AGG-ID: R-9FZXHDOiakLybY74ZfmA_1752661912 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-451d30992bcso51254655e9.2 for ; Wed, 16 Jul 2025 03:31:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752661912; x=1753266712; h=content-transfer-encoding:in-reply-to:organization:autocrypt :content-language:from:references:cc:to:subject:user-agent :mime-version:date:message-id:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=QcznUuIcwG4nXt+4JQ0HOO8HtlWuNhZcwm0Vh8nXhEs=; b=dTVzs84QZp3tx+Mq+OFSMCnsEoki4rD0BOAa5/0O0mFtreavb/KknEekUTjdVxQr0N uCuxMhCr27ROc0uaSEd9jy8VLUMqb8xkqw/MUjO6mQBAEgLwX1oK4QBZqhKNpCMH5nZR T/PZfAGFEpuXMKF7YN0O0/Qmdq2fjXwLsIo7be7LUtfZbHKUF8Kv00nguOy/UCB7BhA6 aeIUo9ZUfDrdD6h5kgwUV++hgsRmi2x+gJXNfrCw2V8+WqwT5eObLUDotU+lkSCRCnwA hQU0TwxDGgFmrqdoGJ5F2wlYK+/Nw1QeohpqqlYNPtRquXo+F7/111aYUyZXABPMs949 eJcw== X-Forwarded-Encrypted: i=1; AJvYcCXMGX89eyKnx+5xepEsqRSYrh8WKzYB0qa2QdB2S5QmRx4Xs78dAaxKBgrxQTpZFLFqffs32Sq7Dw==@kvack.org X-Gm-Message-State: AOJu0YyQFfiH4KkcQSRdwOV+kEqGSWp7FXftoJ1xBqFBVrlK0QqU8U58 IrefpWgbPFllb5WkLZjBj2t5kgdZu7NkImY41cTAg0bnUdFL1RdevNPf7Qyf0VazUzwME18xzFs OgZSwlMQF9AJfD7nThrFAYGc3rZ6LORN1egDioQRv7nzROTlUVjsp X-Gm-Gg: ASbGncvPeD3N5gST5l8HCdlEerCs7F678o1eOVH83X1ErrJSXUKpAAkn3L2aEnLHP63 HD45MfQNVcrfZoowsSDMwh4LzDbQhKsETtk/D29tq/qRX4UodXnoCT0fEB7QdYlJ0wGug66L5an eNS/8Y6/whtqbnlIPAV/TCw47Nx5SU855bViW5wJeAqG1oVCHWtVyVxIFxef29x9h7bFFu16Liu wiQUZUPgPFzMOH4KsyDB9eu/qGbHpWop4tubsc6SlsqCLcGejJ9/pN3r6WLSSMA38U8E8mZF9MN PEE9NhO6KIE4CgWjzVjooFPPNdJxgDSkTylMwhhWIN0SIIk7oThRcJXo+s20TDlEQFmjPQsaI/O yO31dmL+xlrOBKTuoX/HPO8tX1Gf6ikpDZgttdIjLenHU+WiWk5V0W0JC4QDgx0/PRvk= X-Received: by 2002:a05:6000:2912:b0:3a4:e6e6:a026 with SMTP id ffacd0b85a97d-3b60e51c9aemr1507095f8f.28.1752661911990; Wed, 16 Jul 2025 03:31:51 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGAxmPe8HjCZESgVq6F2BLQDo/y7yx6bnhMQEihIPWcHJ07P96sJQUTqU+xqhcxeC2KowpvcQ== X-Received: by 2002:a05:6000:2912:b0:3a4:e6e6:a026 with SMTP id ffacd0b85a97d-3b60e51c9aemr1507056f8f.28.1752661911437; Wed, 16 Jul 2025 03:31:51 -0700 (PDT) Received: from ?IPV6:2003:d8:2f1d:ed00:1769:dd7c:7208:eb33? (p200300d82f1ded001769dd7c7208eb33.dip0.t-ipconnect.de. [2003:d8:2f1d:ed00:1769:dd7c:7208:eb33]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8e14d07sm17694498f8f.66.2025.07.16.03.31.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Jul 2025 03:31:50 -0700 (PDT) Message-ID: Date: Wed, 16 Jul 2025 12:31:47 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 09/21] KVM: guest_memfd: Track guest_memfd mmap support in memslot To: Fuad Tabba , Xiaoyao Li Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com References: <20250715093350.2584932-1-tabba@google.com> <20250715093350.2584932-10-tabba@google.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAmgsLPQFCRvGjuMACgkQTd4Q 9wD/g1o0bxAAqYC7gTyGj5rZwvy1VesF6YoQncH0yI79lvXUYOX+Nngko4v4dTlOQvrd/vhb 02e9FtpA1CxgwdgIPFKIuXvdSyXAp0xXuIuRPQYbgNriQFkaBlHe9mSf8O09J3SCVa/5ezKM OLW/OONSV/Fr2VI1wxAYj3/Rb+U6rpzqIQ3Uh/5Rjmla6pTl7Z9/o1zKlVOX1SxVGSrlXhqt kwdbjdj/csSzoAbUF/duDuhyEl11/xStm/lBMzVuf3ZhV5SSgLAflLBo4l6mR5RolpPv5wad GpYS/hm7HsmEA0PBAPNb5DvZQ7vNaX23FlgylSXyv72UVsObHsu6pT4sfoxvJ5nJxvzGi69U s1uryvlAfS6E+D5ULrV35taTwSpcBAh0/RqRbV0mTc57vvAoXofBDcs3Z30IReFS34QSpjvl Hxbe7itHGuuhEVM1qmq2U72ezOQ7MzADbwCtn+yGeISQqeFn9QMAZVAkXsc9Wp0SW/WQKb76 FkSRalBZcc2vXM0VqhFVzTb6iNqYXqVKyuPKwhBunhTt6XnIfhpRgqveCPNIasSX05VQR6/a OBHZX3seTikp7A1z9iZIsdtJxB88dGkpeMj6qJ5RLzUsPUVPodEcz1B5aTEbYK6428H8MeLq NFPwmknOlDzQNC6RND8Ez7YEhzqvw7263MojcmmPcLelYbfOwU0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCaCwtJQUJG8aPFAAKCRBN3hD3AP+DWlDnD/4k2TW+HyOOOePVm23F5HOhNNd7nNv3 Vq2cLcW1DteHUdxMO0X+zqrKDHI5hgnE/E2QH9jyV8mB8l/ndElobciaJcbl1cM43vVzPIWn 01vW62oxUNtEvzLLxGLPTrnMxWdZgxr7ACCWKUnMGE2E8eca0cT2pnIJoQRz242xqe/nYxBB /BAK+dsxHIfcQzl88G83oaO7vb7s/cWMYRKOg+WIgp0MJ8DO2IU5JmUtyJB+V3YzzM4cMic3 bNn8nHjTWw/9+QQ5vg3TXHZ5XMu9mtfw2La3bHJ6AybL0DvEkdGxk6YHqJVEukciLMWDWqQQ RtbBhqcprgUxipNvdn9KwNpGciM+hNtM9kf9gt0fjv79l/FiSw6KbCPX9b636GzgNy0Ev2UV m00EtcpRXXMlEpbP4V947ufWVK2Mz7RFUfU4+ETDd1scMQDHzrXItryHLZWhopPI4Z+ps0rB CQHfSpl+wG4XbJJu1D8/Ww3FsO42TMFrNr2/cmqwuUZ0a0uxrpkNYrsGjkEu7a+9MheyTzcm vyU2knz5/stkTN2LKz5REqOe24oRnypjpAfaoxRYXs+F8wml519InWlwCra49IUSxD1hXPxO WBe5lqcozu9LpNDH/brVSzHCSb7vjNGvvSVESDuoiHK8gNlf0v+epy5WYd7CGAgODPvDShGN g3eXuA== Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: NaLA6NBlpS3nDv88HHjfSgnovrDwYXM3qAWXfWSuUbU_1752661912 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 74C70C0006 X-Stat-Signature: gi7i674w9zfmpf4sopcs58daf4bo7ms1 X-Rspam-User: X-HE-Tag: 1752661915-262766 X-HE-Meta: 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 Dx6n7RLQ grFRZZ8eMOFroQo2AvB6Hw7Mh2mwiS0NdMD5f8pu6mhAE1pr+MFDTyvbBgKZ2TLpQZqnZN7Hrn+j72oQWvrOpfvjbJjG9KsrBpiNuP+FouBuAUxtPngRGL0yEoCykuK5Tzz+vj/7blvLQ8hGUd67cYqWoDpWlv5xznFz/w2sVXl11HOORO3GJ1vjCsoBQEYT8R5iH 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: List-Subscribe: List-Unsubscribe: On 16.07.25 10:21, Fuad Tabba wrote: > Hi Xiaoyao, > > On Wed, 16 Jul 2025 at 07:11, Xiaoyao Li wrote: >> >> On 7/15/2025 5:33 PM, Fuad Tabba wrote: >>> Add a new internal flag, KVM_MEMSLOT_GMEM_ONLY, to the top half of >>> memslot->flags. This flag tracks when a guest_memfd-backed memory slot >>> supports host userspace mmap operations. It's strictly for KVM's >>> internal use. >> >> I would expect some clarification of why naming it with >> KVM_MEMSLOT_GMEM_ONLY, not something like KVM_MEMSLOT_GMEM_MMAP_ENABLED >> >> There was a patch to check the userspace_addr of the memslot refers to >> the same memory as guest memfd[1], but that patch was dropped. Without >> the background that when guest memfd is mmapable, userspace doesn't need >> to provide separate memory via userspace_addr, it's hard to understand >> and accept the name of GMEM_ONLY. > > The commit message could have clarified this a bit more. Regarding the > rationale for the naming, there have been various threads and live > discussions in the biweekly guest_memfd meeting . Instead of rehashing > the discussion here, I can refer you to a couple [1, 2]. Maybe clarify here: "Add a new internal flag, KVM_MEMSLOT_GMEM_ONLY, to the top half of memslot->flags. This flag tracks when a guest_memfd-backed memory slot supports host userspace mmap operations, which implies that all memory, not just private memory for CoCo VMs, is consumed through guest_memfd: "gmem only" And add a pointer to the list discussion. -- Cheers, David / dhildenb