From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qk1-f173.google.com (mail-qk1-f173.google.com [209.85.222.173]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 907644D8D8E for ; Mon, 20 Jul 2026 19:36:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.222.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784576176; cv=none; b=ZU/LzC/p3upqeAbHXEk75hqfm+GwxshwYMaqgAq2mSd1XbZycSr5DL7aU4Q4wYZ5EsgsmV/nZCV2XXRBOe7nNY8yrVNB0naYBcDoaButipb0fcMqylzSZZS6zs7f9MEwScapmiMoKQmkyBiidnBWX73yblia7u8lmEwE5tD0fyw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784576176; c=relaxed/simple; bh=d0vgqTeVUGBqlLAIGlg3lxl0DoS6vjZ3OvWpJ8TltpE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=VNYQjJa8LaAx2sizC6+LSnt2dZ8Rn3EomzI9Os0lvvcIGmRKUAbZl9BaAGILctXBAQ2TeJjWrnSy0E2qnf6jiJ1hL1r0LzyGpeyvpiY1LY/xVWXtyVAL2k7Biiob6lpneXIqwqPhYzNm8YgMF/5qPEUCAWYOJ8ILXjYDQ673bqA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net; spf=pass smtp.mailfrom=gourry.net; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b=BAB7AlDv; arc=none smtp.client-ip=209.85.222.173 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=gourry.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gourry.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gourry.net header.i=@gourry.net header.b="BAB7AlDv" Received: by mail-qk1-f173.google.com with SMTP id af79cd13be357-92e622cc874so782492185a.0 for ; Mon, 20 Jul 2026 12:36:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1784576171; x=1785180971; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=agF9dzqU876M91BxnILPGKGHMrmtsRIzpFbV5gzpkC4=; b=BAB7AlDvWJHSFPAvkomx/HPQLnjetc2eOumGasbyoiIdK7eAEQ8neaEEzMLwN9RfJI sGalEaKcKCfYycRERfXaRftbJoKXpjSbEvWDQKqpa9bV3KIep8Roae0eTcde9XoC6VCw z0g+gazO+csCoUmzqtME3Wz61SMtIyoU5zys2pAN+rZN85E+V4s1q6QtKpIIRf9QMg4L LimFgt7swKdS6GjcdZOH4ks/op8FvYadLCVyG/VXBQYNL2+9mb2AELxtJwtbyTSNRYCE RJnBP/Q2J2U+5bb6SrgwoL0Htg+z514Ij3bXMBvEuYyHAntLtQrElBX1niXS2N2K5zeD d8mQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784576171; x=1785180971; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=agF9dzqU876M91BxnILPGKGHMrmtsRIzpFbV5gzpkC4=; b=bRtvnpONuIGDN8mrs4D3N2kwzOpTVh4wAt1dMRpK5BwE9YX6B/JYIuYsjEt4EcAG7f 48acK/NGexV83mAGWkjFKgtW/o15cRPJPjUHKIp5V+c/pANQLqHjy8swQlPZ5N3ZXgmK KVPBg0/PVOWHjHDFjWPjCcoZpG/dZy/tVihVs82vgDTuvSFVxszERgBQRGMr6evhtSGm S3TgYZltsN/qVz4juo9pMFIdspGofjHfZtEdhzVD8WZrSjgVB68bQuNwarxheo11JBrY dWcp7Umz4esFyG+2oPnvRUuOvwUMply93+UJ5feakctgBl2t0eHF2Uo1iT9lmteX5Bep FwFQ== X-Forwarded-Encrypted: i=1; AHgh+RqnBsTAJJ8EmSPckoahbNCoyZabqC/OE+U+RkvEHQDSHlwg6JKcJN4EY+7f91Gd48bTVw33MbjOPrDBtU4=@vger.kernel.org X-Gm-Message-State: AOJu0YzivY0QWPyqI0yQWo6i+8tWI9008sEoeeWzfDTtul01/5mnUDn9 wLw+WVEQ+DKHQjfte0pDI5vON0Uq4u4Rz9ov3wtuhrOcxaL1YFkvmCmJsj1Ox1lLkPY= X-Gm-Gg: AfdE7cli6s7dsByWpRo9FUpMz8S+XTM6n3Oet0DN6IQZ03HHocktBx/nYpYm+t4Gz4n nOGuvHZwbWpTzCr4+LmotyYvReGwQR6UrgHnJoRFJa55oguwsy1S9vJkScdDQcvt8w167sztps1 CEOWm/VaLXirFfmRfWwb8PrMnGGII5GxVoYS9u1PEN5jTnmVyTI1PtN+tNxOauHvbspy8UystQI 8ilJZfUFp5tN3RoN5Hj7QpQi/Uscr7MnHhM8LyE4FGFOI6fVpO0NbwOAss1ilbfIRIBarPdzCES ZnAnfR2DjscJDGQ5kUBCznqN2GR1xhmiVK5xbmzkA9fu5JkvSzzJkW6qvqsQeXURiMGos9h3j7J rJo2kD4GdS0Y2dMH4JqFLwkk+tRfhOahvlg1D4PkpJYHIb4XcqsvctcFBEgLSNG07Yc2oIRDUVe bKoyQREVPj9tM535hcle3CcWlqQGJelScgf0lhJmT0ua/z2KdKoRy7ZoG8UTMQ1z62qssElTvAp A== X-Received: by 2002:a05:620a:4082:b0:92e:59b0:df08 with SMTP id af79cd13be357-930b3ec7086mr1655803085a.3.1784576170762; Mon, 20 Jul 2026 12:36:10 -0700 (PDT) Received: from gourry-fedora-PF4VCD3F.lan (pool-173-79-60-52.washdc.fios.verizon.net. [173.79.60.52]) by smtp.gmail.com with ESMTPSA id af79cd13be357-930b545e47bsm957792285a.35.2026.07.20.12.36.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jul 2026 12:36:10 -0700 (PDT) From: Gregory Price To: linux-mm@kvack.org Cc: Zhigang.Luo@amd.com, arun.george@samsung.com, balbirs@nvidia.com, brendan.jackman@linux.dev, yuzenghui@huawei.com, apopple@nvidia.com, alucerop@amd.com, matthew.brost@intel.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, corbet@lwn.net, skhan@linuxfoundation.org, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, alison.schofield@intel.com, osandov@osandov.com, jannh@google.com, pfalcato@suse.de, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, pbonzini@redhat.com, osalvador@suse.de, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, longman@redhat.com, ridong.chen@linux.dev, tj@kernel.org, mkoutny@suse.com, sj@kernel.org, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, baolin.wang@linux.alibaba.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, usama.arif@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, driver-core@lists.linux.dev, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-debuggers@vger.kernel.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, cgroups@vger.kernel.org, damon@lists.linux.dev, linux-kselftest@vger.kernel.org, kernel-team@meta.com Subject: [PATCH v5 35/36] KVM: guest_memfd: bind backing memory to a NUMA node at creation Date: Mon, 20 Jul 2026 15:34:29 -0400 Message-ID: <20260720193431.3841992-36-gourry@gourry.net> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260720193431.3841992-1-gourry@gourry.net> References: <20260720193431.3841992-1-gourry@gourry.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit guest_memfd presently allocates its page-cache folios through a per-inode shared mempolicy (kvm_gmem_get_folio()). Today that policy can only be set after the fact, via mbind() on a host mmap of the fd. This requires the fd to be mmap-able and cannot reach folios that are only ever guest-faulted (no host VMA). Neither holds for a non-mappable (confidential) guest_memfd. Add GUEST_MEMFD_FLAG_BIND_NODE. When set, KVM builds an MPOL_BIND policy for the requested node and installs it over the whole inode's shared policy, so every folio is allocated on the requested node with no userspace mbind(). The flag is advertised through KVM_CAP_GUEST_MEMFD_FLAGS only when CONFIG_NUMA is enabled. Suggested-by: Dave Jiang Co-developed-by: Dave Jiang Signed-off-by: Dave Jiang Signed-off-by: Gregory Price Assisted-by: Claude:claude-opus-4-8 --- include/linux/kvm_host.h | 3 +++ include/uapi/linux/kvm.h | 5 ++++- virt/kvm/guest_memfd.c | 39 +++++++++++++++++++++++++++++++++++++-- 3 files changed, 44 insertions(+), 3 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index ab8cfaec82d31..f6448a73d464c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -739,6 +739,9 @@ static inline u64 kvm_gmem_get_supported_flags(struct kvm *kvm) if (!kvm || kvm_arch_supports_gmem_init_shared(kvm)) flags |= GUEST_MEMFD_FLAG_INIT_SHARED; + if (IS_ENABLED(CONFIG_NUMA)) + flags |= GUEST_MEMFD_FLAG_BIND_NODE; + return flags; } #endif diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 419011097fa8e..a8ff150e2cbb7 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1654,11 +1654,14 @@ struct kvm_memory_attributes { #define KVM_CREATE_GUEST_MEMFD _IOWR(KVMIO, 0xd4, struct kvm_create_guest_memfd) #define GUEST_MEMFD_FLAG_MMAP (1ULL << 0) #define GUEST_MEMFD_FLAG_INIT_SHARED (1ULL << 1) +#define GUEST_MEMFD_FLAG_BIND_NODE (1ULL << 2) struct kvm_create_guest_memfd { __u64 size; __u64 flags; - __u64 reserved[6]; + __u32 node; + __u32 pad; + __u64 reserved[5]; }; #define KVM_PRE_FAULT_MEMORY _IOWR(KVMIO, 0xd5, struct kvm_pre_fault_memory) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index f0e5da4908660..de320df08e0ff 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -456,6 +456,26 @@ static struct mempolicy *kvm_gmem_get_policy(struct vm_area_struct *vma, */ return mpol_shared_policy_lookup(&GMEM_I(inode)->policy, pgoff); } + +static int kvm_gmem_bind_node(struct inode *inode, int node) +{ + struct mempolicy *pol; + int err; + + pol = mpol_bind_node(node); + if (IS_ERR(pol)) + return PTR_ERR(pol); + + err = mpol_set_shared_policy_range(&GMEM_I(inode)->policy, 0, + MAX_LFS_FILESIZE >> PAGE_SHIFT, pol); + mpol_put(pol); + return err; +} +#else +static int kvm_gmem_bind_node(struct inode *inode, int node) +{ + return -EINVAL; +} #endif /* CONFIG_NUMA */ static const struct vm_operations_struct kvm_gmem_vm_ops = { @@ -557,7 +577,7 @@ bool __weak kvm_arch_supports_gmem_init_shared(struct kvm *kvm) return true; } -static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) +static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags, int node) { static const char *name = "[kvm-gmem]"; struct gmem_file *f; @@ -598,6 +618,12 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) GMEM_I(inode)->flags = flags; + if (flags & GUEST_MEMFD_FLAG_BIND_NODE) { + err = kvm_gmem_bind_node(inode, node); + if (err) + goto err_inode; + } + file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR, &kvm_gmem_fops); if (IS_ERR(file)) { err = PTR_ERR(file); @@ -630,6 +656,7 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) { loff_t size = args->size; u64 flags = args->flags; + int node = NUMA_NO_NODE; if (flags & ~kvm_gmem_get_supported_flags(kvm)) return -EINVAL; @@ -637,7 +664,15 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) if (size <= 0 || !PAGE_ALIGNED(size)) return -EINVAL; - return __kvm_gmem_create(kvm, size, flags); + if (flags & GUEST_MEMFD_FLAG_BIND_NODE) { + if (args->pad || args->node >= MAX_NUMNODES) + return -EINVAL; + node = args->node; + } else if (args->node || args->pad) { + return -EINVAL; + } + + return __kvm_gmem_create(kvm, size, flags, node); } int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, -- 2.53.0-Meta