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 34716D2F7D8 for ; Wed, 16 Oct 2024 23:49:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8978F6B007B; Wed, 16 Oct 2024 19:49:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 847E66B0082; Wed, 16 Oct 2024 19:49:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6E8016B0083; Wed, 16 Oct 2024 19:49:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 4A47D6B007B for ; Wed, 16 Oct 2024 19:49:42 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 65BE9ABBFD for ; Wed, 16 Oct 2024 23:49:21 +0000 (UTC) X-FDA: 82681109910.24.5A103A6 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf24.hostedemail.com (Postfix) with ESMTP id CD4D318000E for ; Wed, 16 Oct 2024 23:49:37 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="Aoet//z6"; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf24.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1729122462; a=rsa-sha256; cv=none; b=uALPTBzc/QscgOXY7+XnB0UwHj4R3uBYSIx6aYqABybVxsCKwxakAxLwRKIzpg1hDfgrq/ LEZXv83B225HdMZAK8SfvVm/hpJfJG5MF8KrCDCNe7AlcO41+SSRo+eRjjJv8JIT2eeiSA Hp10/f1qoDUx6Xva0s5em64C3Tt3Ukk= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="Aoet//z6"; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf24.hostedemail.com: domain of peterx@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=peterx@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1729122462; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tdCmZ9Hln4F3TV8mrnoM2AWNUvAQWn+CFerwHQC2qPI=; b=Fuaqtz54hrPKLkmbo1RdpQGf6PHS2i/iQXGNmYNRgCUnU9mAISj/b5CMc1hJGnCsjVAdVe ZjsHlC6asTjjvAKdo4GDPmIxtF1Hsihbj6Bn6l8kuHtu5v2uTJP28/AleaFSJICRB+4D4N mnQ2PRa3hpBvtomunpPRTIWRm3f8NZo= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1729122579; 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=tdCmZ9Hln4F3TV8mrnoM2AWNUvAQWn+CFerwHQC2qPI=; b=Aoet//z6df3EZ5/K3ncRLDmGfx+TgCVSlE44xFn3VVI1CVsBXVmT7NedB5bIfiVkQX63rF Zw7PuCNP0nzOIvq/Zae153/eduCF+aOn+aMEcYmMNU2ZCkd0gfnSjspCqOkTwr9wHXT/f9 0Sc9iv8IF6orCiE0W5vYuu81Zr3hjVw= Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-625--rr-KWsHNhCCjMPo0PMn-w-1; Wed, 16 Oct 2024 19:49:37 -0400 X-MC-Unique: -rr-KWsHNhCCjMPo0PMn-w-1 Received: by mail-qt1-f197.google.com with SMTP id d75a77b69052e-45efe547818so5811631cf.1 for ; Wed, 16 Oct 2024 16:49:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729122577; x=1729727377; 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=tdCmZ9Hln4F3TV8mrnoM2AWNUvAQWn+CFerwHQC2qPI=; b=FeI0hUCXNA3tcSaZAbduQsjHLF3K3Z4gRbaFN/eb3eTV6FmtzMabo1vql6dej88YxV rhLL48xyZlBoqpCly5muQy6vyYfjgRwDwk36f4rhcaESxbioPSor+HAPid7Tutme6DAg WIEAJ7MFa37v3uIO/rgr+aKVA+LfxbBpF5SLjiFLVo5GuLANGFp2wadxmgS45cXmb3ek 20+pUjZ31JVyfWFpgwwGhdg+ZH5kssvKmr091EfMxIwORHppmX/aAfont9XN3yp9nVJ3 bfe7+/th8YMUVWbN1ViO4XNDNZQGuHR/eBMS3O3QDkfLw0pQ60jVHf+6r/b1yhAAtHkh qEwg== X-Forwarded-Encrypted: i=1; AJvYcCWZO9NwT3WUzYkb5z/IOfSZLhiCx+tk1aHx7tRal6QwzuLuuCFe4XCwlcdeXHo65Bgq4HYHXY6wtA==@kvack.org X-Gm-Message-State: AOJu0Yw5mtKFUxGTMpPN00EYT/gaFjIrW1JsixVnYii0wxPQ0Tm1RypJ r2oZyp0E+LMq1o/UVUzkQXuAy2YPZVCMdoMfxK6P1pfWODE3myrdN478A1jnSN9A5lVGO5+zpE7 r830m1I5dGsDLgwdYqePr8KbMdVfsQjpo6oPNj6MmTdFTVdTr X-Received: by 2002:a05:6214:5541:b0:6cb:c994:160b with SMTP id 6a1803df08f44-6cbf0044c8amr256327836d6.18.1729122577444; Wed, 16 Oct 2024 16:49:37 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHmipPb+bjkN1rVUXoFZ8wnXohSPm9OSuWjAO54jD6Ayz0Tg/8Zo1OktuIrYNhuOlrop+rkMQ== X-Received: by 2002:a05:6214:5541:b0:6cb:c994:160b with SMTP id 6a1803df08f44-6cbf0044c8amr256327556d6.18.1729122577114; Wed, 16 Oct 2024 16:49:37 -0700 (PDT) Received: from x1n (pool-99-254-114-190.cpe.net.cable.rogers.com. [99.254.114.190]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6cc2290fa71sm22636456d6.27.2024.10.16.16.49.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Oct 2024 16:49:35 -0700 (PDT) Date: Wed, 16 Oct 2024 19:49:31 -0400 From: Peter Xu To: Jason Gunthorpe Cc: David Hildenbrand , Ackerley Tng , tabba@google.com, quic_eberman@quicinc.com, roypat@amazon.co.uk, rientjes@google.com, fvdl@google.com, jthoughton@google.com, seanjc@google.com, pbonzini@redhat.com, zhiquan1.li@intel.com, fan.du@intel.com, jun.miao@intel.com, isaku.yamahata@intel.com, muchun.song@linux.dev, erdemaktas@google.com, vannapurve@google.com, qperret@google.com, jhubbard@nvidia.com, willy@infradead.org, shuah@kernel.org, brauner@kernel.org, bfoster@redhat.com, kent.overstreet@linux.dev, pvorel@suse.cz, rppt@kernel.org, richard.weiyang@gmail.com, anup@brainfault.org, haibo1.xu@intel.com, ajones@ventanamicro.com, vkuznets@redhat.com, maciej.wieczor-retman@intel.com, pgonda@google.com, oliver.upton@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 26/39] KVM: guest_memfd: Track faultability within a struct kvm_gmem_private Message-ID: References: <1d243dde-2ddf-4875-890d-e6bb47931e40@redhat.com> <20241016225157.GQ3559746@nvidia.com> MIME-Version: 1.0 In-Reply-To: <20241016225157.GQ3559746@nvidia.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: CD4D318000E X-Stat-Signature: y1nq3rep6jyq636k7jw83eyfnpym4o6i X-Rspam-User: X-HE-Tag: 1729122577-376126 X-HE-Meta: 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 pRk8LDvS TIejd0dUQAsV9rDa2rJ/ONWrXoI5EShnbJxqF/wWhSHYf0jDBS9IX1E2tdbk0t1l2ohyPd3taqVAXxw4e8hIuwfmiWYADXThCO6oQNDRqxG2L3HYa9z4TX8zcc9PWfXSBAcsPXOXwEX+ai7SidTbQODFo3EnRs+UtQfcqI4ItmJxx9wyswnji2v9FLfAuNkfFRKzeuRoPQ3071WBwqlRHJpYACpolfMP0va+qijwGaMY6tJTqB6s4FXAFlL4y/bd7SmeP4pGM5YyHzj0fd2g4UkjkdtBuljkmWYBiRxptDcv8zrxCCvMB5p3/bqLBFrW5iTkv/TWreVmNNYpRBsSWXXAGOhzfFr1hkRTkPlbgO1f6XpjoOcfmcB328UH7j0VI2YF83b0GOrix6qVyHikSrUIf7ZzAVIKp0KyB0CwD1FgLXDjflM3sBwNMviWrJs5H8YFylWrSC2zjkoW+72gONcneiWdKGGf2n8QD1QEvc1i8VIA= 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 Wed, Oct 16, 2024 at 07:51:57PM -0300, Jason Gunthorpe wrote: > On Wed, Oct 16, 2024 at 04:16:17PM -0400, Peter Xu wrote: > > > > Is there chance that when !CoCo will be supported, then external modules > > (e.g. VFIO) can reuse the old user mappings, just like before gmemfd? > > > > To support CoCo, I understand gmem+offset is required all over the places. > > However in a non-CoCo context, I wonder whether the other modules are > > required to stick with gmem+offset, or they can reuse the old VA ways, > > because how it works can fundamentally be the same as before, except that > > the folios now will be managed by gmemfd. > > My intention with iommufd was to see fd + offest as the "new" way > to refer to all guest memory and discourage people from using VMA > handles. Does it mean anonymous memory guests will not be supported at all for iommufd? Indeed it's very rare now, lose quite some flexibility (v.s. fd based), and I can't think of a lot besides some default configs or KSM users (which I would expect rare), but still I wonder there're other use cases that people would still need to stick with anon, hence fd isn't around. Thanks, -- Peter Xu