From patchwork Wed Nov 13 22:34:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Elliot Berman X-Patchwork-Id: 843239 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA3EF13959D; Wed, 13 Nov 2024 22:34:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.180.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731537294; cv=none; b=crVfvvTn+YAuYSGv8Oy5KsWwM2PZDToKwVcyCudv6rU8vNLjtpBWtVTTwBW94MedmsTR9gHjvFVGwYkSoJNeLVR3orXA+XgOlUa1mPQi4RFtpdsYrAYH0IHTvW2qv0I1s7BJ7Ztmxrri0ZhwG+nysf2YyAy78GMPF0KONrd/Fqk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731537294; c=relaxed/simple; bh=AOVX+Q3LP2qMURxMX1tJm7ekf6MwcEHpxO8hdpqc/3s=; h=From:Subject:Date:Message-ID:MIME-Version:Content-Type:To:CC; b=r8YyPrOEGUhGzvNI4eiQid/afEJHmOwf4GmITcvGPTWlmIQpju0FT4acNNBOKAop0Xci1GxH6s5Yy56n2z287wF//Ng413kH/Yoyv1y7Me91e9Gics1+iHLOHD0UizGtDKOZ7XPTqCsYPpJS55eFOv2SDgMe1EmfcGqMFscLVpU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com; spf=pass smtp.mailfrom=quicinc.com; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b=OfM8qVxx; arc=none smtp.client-ip=205.220.180.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=quicinc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=quicinc.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=quicinc.com header.i=@quicinc.com header.b="OfM8qVxx" Received: from pps.filterd (m0279873.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 4ADHxknj027135; Wed, 13 Nov 2024 22:34:40 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h= cc:content-transfer-encoding:content-type:date:from:message-id :mime-version:subject:to; s=qcppdkim1; bh=BtXq4E+cGX3BSnPnoNAAsr KGpw88rLXe/Rc0cHF3mes=; b=OfM8qVxx9vlTJMtOL/p+eK5Y+FODNdCZt23nNE yQ2c4UragxbRFZpl4qqp4hNnfLtl1DvTI2su5t6rSN6Jc8IB0KUy7dD59rvRDRfO nT8FRtPrLYSnf0IpTBuo3ByIg9miORIpXKpr5g2ICMu3molFSXVO4bTKS37uRWVU 4WtpMOy5WHlYraxXWhVR2XSZTlkaEiA59jplSK7bu7otnHVetlr8OAhBn+iBgQYj ZRMcZ9LOy4b5RwO+9TET/Ko0D6ubk9bUY9oRMX7LvUE6DFZxjRxDK3rQMQPoqDed ofTM8K+8PxK77KG3uhFqBnKDaJIMUWqZv8DNBNkWSD8CP3EQ== Received: from nasanppmta04.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 42w10jrn10-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 13 Nov 2024 22:34:40 +0000 (GMT) Received: from nasanex01b.na.qualcomm.com (nasanex01b.na.qualcomm.com [10.46.141.250]) by NASANPPMTA04.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 4ADMYdxo006632 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 13 Nov 2024 22:34:39 GMT Received: from hu-eberman-lv.qualcomm.com (10.49.16.6) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Wed, 13 Nov 2024 14:34:38 -0800 From: Elliot Berman Subject: [PATCH RFC v3 0/2] mm: Refactor KVM guest_memfd to introduce guestmem library Date: Wed, 13 Nov 2024 14:34:35 -0800 Message-ID: <20241113-guestmem-library-v3-0-71fdee85676b@quicinc.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAHspNWcC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyjHUUlJIzE vPSU3UzU4B8JSMDIxNDQ0Mj3fTS1OKS3NRc3ZzMpKLEokpdMwtjM+PkJCNLQwszJaC2gqLUtMw KsJHRSkFuzkqxtbUAnc24EmcAAAA= X-Change-ID: 20241112-guestmem-library-68363cb29186 To: Paolo Bonzini , Andrew Morton , Sean Christopherson , "Fuad Tabba" , Ackerley Tng , "Mike Rapoport" , "H. Peter Anvin" CC: James Gowans , , , , , , , Elliot Berman X-Mailer: b4 0.14.2 X-ClientProxiedBy: nalasex01b.na.qualcomm.com (10.47.209.197) To nasanex01b.na.qualcomm.com (10.46.141.250) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: rGKUzBUjULE8r9lkutNxPo0AT6PlGYjw X-Proofpoint-GUID: rGKUzBUjULE8r9lkutNxPo0AT6PlGYjw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 suspectscore=0 spamscore=0 priorityscore=1501 bulkscore=0 mlxlogscore=849 impostorscore=0 lowpriorityscore=0 phishscore=0 clxscore=1011 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2411130185 In preparation for adding more features to KVM's guest_memfd, refactor and introduce a library which abtracts some of the core-mm decisions about managing folios associated with guest memory. The goal of the refactor serves two purposes: 1. Provide an easier way to reason about memory in guest_memfd. KVM needs to support multiple confidentiality models (TDX, SEV, pKVM, Arm CCA). These models support different semantics for when the host can(not) access guest memory. An abstraction for the allocator and managing the state of pages will make it eaiser to reason about the state of folios within the guest_memfd. 2. Provide a common implementation for other users such as Gunyah [1] and guestmemfs [2]. In this initial series, I'm seeking comments for the line I'm drawing between library and user (KVM). I've not introduced new functionality in this series; the first new feature will probably be Fuad's mappability patches [3]. I've decided to only bring out the address_space from guest_memfd as it seemed the simplest approach. In the current iteration, KVM "attaches" the guestmem to the inode. I expect we'll want to provide some helpers for inode, file, and vm operations when it's relevant to mappability/accessiblity/faultability. I'd appreciate any feedback, especially on how much we should pull into the guestmem library. [1]: https://lore.kernel.org/lkml/20240222-gunyah-v17-0-1e9da6763d38@quicinc.com/ [2]: https://lore.kernel.org/all/20240805093245.889357-1-jgowans@amazon.com/ [3]: https://lore.kernel.org/all/20241010085930.1546800-3-tabba@google.com/ Changes in v3: - Refactor/extract only the address_space - Link to v2: https://lore.kernel.org/all/20240829-guest-memfd-lib-v2-0-b9afc1ff3656@quicinc.com/ Changes in v2: - Significantly reworked to introduce "accessible" and "safe" reference counters - Link to v1: https://lore.kernel.org/r/20240805-guest-memfd-lib-v1-0-e5a29a4ff5d7@quicinc.com Signed-off-by: Elliot Berman --- Elliot Berman (2): KVM: guest_memfd: Convert .free_folio() to .release_folio() mm: guestmem: Convert address_space operations to guestmem library MAINTAINERS | 2 + include/linux/guestmem.h | 33 +++++++ mm/Kconfig | 3 + mm/Makefile | 1 + mm/guestmem.c | 232 +++++++++++++++++++++++++++++++++++++++++++++++ virt/kvm/Kconfig | 1 + virt/kvm/guest_memfd.c | 107 +++++++--------------- 7 files changed, 305 insertions(+), 74 deletions(-) --- base-commit: 5cb1659f412041e4780f2e8ee49b2e03728a2ba6 change-id: 20241112-guestmem-library-68363cb29186 Best regards,