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 F215ECFD376 for ; Sun, 30 Nov 2025 11:18:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 11DD56B000A; Sun, 30 Nov 2025 06:18:24 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 0A7B46B000C; Sun, 30 Nov 2025 06:18:24 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB15B6B000D; Sun, 30 Nov 2025 06:18:23 -0500 (EST) 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 D3E306B000A for ; Sun, 30 Nov 2025 06:18:23 -0500 (EST) Received: from smtpin22.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 778A1132541 for ; Sun, 30 Nov 2025 11:18:23 +0000 (UTC) X-FDA: 84167024886.22.AC06B30 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf26.hostedemail.com (Postfix) with ESMTP id 219B7140014 for ; Sun, 30 Nov 2025 11:18:21 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=XUtziVFw; spf=pass (imf26.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@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=1764501502; 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-transfer-encoding:content-transfer-encoding: in-reply-to:references:dkim-signature; bh=i7R8+9qMl8wh0X5wU6czbvLNsq7fHz+lMo4qPQRav9A=; b=PGEb4GVyh1oRB2qu9la4X4hp69ReFMsIGttl2NpSsLRldT2XtaeIEx3DxXOKX4vxGP+MaN vvSAQOKz3R0csTW2ZW/W01eF/DnyF0iiNTLxuBkJutt+r3yJtXJ2Ov7jL/m2kVbL2TJ8ns CsdYD6y4G9tcl0jcg/aa/0Ju+ncXZPo= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1764501502; a=rsa-sha256; cv=none; b=mB5o52sJweGofuaAA94tkHF+h/TyOlU5VK9vTINX58M1LowvDxBZiD3OfeLCEqxBXjUgCW 6u6YdzboYf5+O2vlmCi00hzkvhqKNVEMJafOMthwrmZ0kXV99Q8qswDANjSUKbquZaBFye 6eCrSttyyrP12SqJE0IRMBF225Er3q0= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=XUtziVFw; spf=pass (imf26.hostedemail.com: domain of rppt@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=rppt@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 362C260127; Sun, 30 Nov 2025 11:18:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA9E7C4CEF8; Sun, 30 Nov 2025 11:18:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764501500; bh=QWyCUWNr5EiAGbEinbC1SqyvrF+pTj5s8nlr0+kSaV4=; h=From:To:Cc:Subject:Date:From; b=XUtziVFwxT+NlKvaS6WSYT+hiz0mrSRU2i7WVNjkPJridMQi1gJVaxfwESV5hKMLG BN3/0ZxZ/2DXLu6KtyIAMR3OGP+BuHSB7mPzKRRbzKyPqJR8YmW7n/weFmExIqYmtd 7S3JsaPSzIUgMK9FlfeSl9MJQo32lLw65KrX4tiLtUyULE/RclDDkSu7WAu6Tv55J3 gf46siqJ5aWDVA7l8SrR6snvp0GwbHKUcRBMPamwN8p8iGNLcKkG/4XQ1p0ZejStcH jf9uLE+kQcOwTjd9m8m1xzWcw4fqekafIhmzyolIu/YVxYX02l2rPQaNJa9U1vNIoc pL0mfDDnUxd0A== From: Mike Rapoport To: linux-mm@kvack.org Cc: Andrea Arcangeli , Andrew Morton , Axel Rasmussen , Baolin Wang , David Hildenbrand , Hugh Dickins , James Houghton , "Liam R. Howlett" , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Nikita Kalyazin , Paolo Bonzini , Peter Xu , Sean Christopherson , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH v3 0/5] mm, kvm: add guest_memfd support for uffd minor faults Date: Sun, 30 Nov 2025 13:18:07 +0200 Message-ID: <20251130111812.699259-1-rppt@kernel.org> X-Mailer: git-send-email 2.51.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 219B7140014 X-Stat-Signature: 6o9pzk7qw9bp4cfiy9cr5xdi5stbxjeh X-Rspam-User: X-HE-Tag: 1764501501-781517 X-HE-Meta: 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 GhU9V7vX 1oXqh 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: From: "Mike Rapoport (Microsoft)" Hi, These patches allow guest_memfd to notify userspace about minor page faults using userfaultfd and let userspace to resolve these page faults using UFFDIO_CONTINUE. To allow UFFDIO_CONTINUE outside of the core mm I added a get_folio_noalloc() callback to vm_ops that allows an address space backing a VMA to return a folio that exists in it's page cache (patch 2) In order for guest_memfd to notify userspace about page faults, there is a new VM_FAULT_UFFD_MINOR that a ->fault() handler can return to inform the page fault handler that it needs to call handle_userfault() to complete the fault (patch 3). Patch 4 plumbs these new goodies into guest_memfd. This series is the minimal change I've been able to come up with to allow integration of guest_memfd with uffd and while refactoring uffd and making mfill_atomic() flow more linear would have been a nice improvement, it's way out of the scope of enabling uffd with guest_memfd. v3 changes: * rename ->get_folio() to ->get_folio_noalloc() * fix build errors reported by kbuild * pull handling of UFFD_MINOR out of hotpath in __do_fault() * update guest_memfs changes so its ->fault() and ->get_folio_noalloc() follow the same semantics as shmem and hugetlb. * s/MISSING/MINOR/g in changelogs * added review tags v2: https://lore.kernel.org/all/20251125183840.2368510-1-rppt@kernel.org * rename ->get_shared_folio() to ->get_folio() * hardwire VM_FAULF_UFFD_MINOR to 0 when CONFIG_USERFAULTFD=n v1: https://patch.msgid.link/20251123102707.559422-1-rppt@kernel.org * Introduce VM_FAULF_UFFD_MINOR to avoid exporting handle_userfault() * Simplify vma_can_mfill_atomic() * Rename get_pagecache_folio() to get_shared_folio() and use inode instead of vma as its argument rfc: https://patch.msgid.link/20251117114631.2029447-1-rppt@kernel.org Mike Rapoport (Microsoft) (4): userfaultfd: move vma_can_userfault out of line userfaultfd, shmem: use a VMA callback to handle UFFDIO_CONTINUE mm: introduce VM_FAULT_UFFD_MINOR fault reason guest_memfd: add support for userfaultfd minor mode Nikita Kalyazin (1): KVM: selftests: test userfaultfd minor for guest_memfd include/linux/mm.h | 9 ++ include/linux/mm_types.h | 10 +- include/linux/userfaultfd_k.h | 36 +------ mm/memory.c | 5 +- mm/shmem.c | 20 +++- mm/userfaultfd.c | 80 ++++++++++++--- .../testing/selftests/kvm/guest_memfd_test.c | 97 +++++++++++++++++++ virt/kvm/guest_memfd.c | 33 ++++++- 8 files changed, 236 insertions(+), 54 deletions(-) base-commit: ac3fd01e4c1efce8f2c054cdeb2ddd2fc0fb150d -- 2.51.0