From patchwork Tue Mar 18 16:20:40 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fuad Tabba X-Patchwork-Id: 14021245 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 1A981C28B28 for ; Tue, 18 Mar 2025 16:20:55 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E4E3C280011; Tue, 18 Mar 2025 12:20:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CEB4028000B; Tue, 18 Mar 2025 12:20:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7CC3280011; Tue, 18 Mar 2025 12:20:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 8488728000B for ; Tue, 18 Mar 2025 12:20:52 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 0953DC13A7 for ; Tue, 18 Mar 2025 16:20:54 +0000 (UTC) X-FDA: 83235185628.13.2D9361A Received: from mail-wr1-f73.google.com (mail-wr1-f73.google.com [209.85.221.73]) by imf29.hostedemail.com (Postfix) with ESMTP id CF5D1120006 for ; Tue, 18 Mar 2025 16:20:51 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=OvZbXHgF; spf=pass (imf29.hostedemail.com: domain of 3Yp3ZZwUKCEk4lmmlrzzrwp.nzxwty58-xxv6lnv.z2r@flex--tabba.bounces.google.com designates 209.85.221.73 as permitted sender) smtp.mailfrom=3Yp3ZZwUKCEk4lmmlrzzrwp.nzxwty58-xxv6lnv.z2r@flex--tabba.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742314852; 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=v5BCJQxA8skMwKLEJl+6kBnMuf3AEUFL1v827aCOrto=; b=SwMut1aFh63IJzH3S3t00qO9q3T8xm3GHk8LoWDhrkeXT7pwnKUqY5yPx96yu//lU2crYm cuHD+gzFMRqWJNYAs+QrpmE/M2pfLLHnAa8lDqgTssPYXyGrf7FlSUKC6WSTOyDkwe+z2R UGGdxuxvH2IEbjx1zMlZWIrAvgdIg7A= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742314852; a=rsa-sha256; cv=none; b=wh0fnW4hk8c0Oef+l8QJSZUNAAO531w9ECKIGyvVCXC0PPPTdyFz2LlpCSF+nCE25Vb9IB Se1eTOIrTL4iRBfDMwwBRUKgqr2f1Jp/+i6Isvk13YDGsVStvwHHpDKnGDSYjleM4BpXfV Owu1JcHdgxtroENzQUFVmHmLRzeTCPw= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=google.com header.s=20230601 header.b=OvZbXHgF; spf=pass (imf29.hostedemail.com: domain of 3Yp3ZZwUKCEk4lmmlrzzrwp.nzxwty58-xxv6lnv.z2r@flex--tabba.bounces.google.com designates 209.85.221.73 as permitted sender) smtp.mailfrom=3Yp3ZZwUKCEk4lmmlrzzrwp.nzxwty58-xxv6lnv.z2r@flex--tabba.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com Received: by mail-wr1-f73.google.com with SMTP id ffacd0b85a97d-39141ffa913so3500855f8f.2 for ; Tue, 18 Mar 2025 09:20:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1742314850; x=1742919650; darn=kvack.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=v5BCJQxA8skMwKLEJl+6kBnMuf3AEUFL1v827aCOrto=; b=OvZbXHgFAL9NnKt+Iy/lq/KKxo0wWrbJ7i4lIlqzvdEeiLaJqLZhIS94ivEOMzyZwL D5b9qYcVnnyhVFn85OpEEO05J7lbR9e0jgTAQkag62eVptK6+HOBOZhGRUPTYGf1ymkU TOeuGdFvP6GNluf3/GyEC8KjvwcKP6il6ErmdSyUsqdDpyh7Z+IhmqoiLKjneTQAoxZV I3avlitJcOYE3lZOujl+kmTzc7KuRQknxB+o4ppiHRovO4V5S+lTFX3p3BvFwQytur2x pizqHDhF+x4++48L5yvbNFrMOaGi8KZth1gDMnFFXZbQ2UMn3dDND2FJMrjfuXfCNPa9 /DZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1742314850; x=1742919650; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=v5BCJQxA8skMwKLEJl+6kBnMuf3AEUFL1v827aCOrto=; b=YjvPnQVLKPh4/Vg2+1HEk8jD7DU1RkVeWEaKJtKU8kOtWLvkUxZs1Y1aXPwGxBaNVC 4dVt4l80pUnm4SEsiij0rJqMvUwYJIkaIIWJ7uLLoCQTKn34hbLLZv0MaStPFgpqa0ra gO2AYioDrlMgJUPVqw13iG4XkG2CgNJ2Aa65I7iO9N55EHwKjyBXVKdurG4rX/PPPP7Q XC7iZNhiA9mX7aCUj6lD3eanjcl1ss7Wy+g2BwJpyBBvLAvIa0UIQYFtdGsoNOR5QNwe DG/creldEnwP0GgGLlsCvPEfrB2dqk98/oupz7pps8ltswUX/6/V+/M/2V908OTummqC 4HKw== X-Forwarded-Encrypted: i=1; AJvYcCVuoBbGcdkChD3Lm0WMpVc0HSh2BS041CcFGhmdIYDcGDf8Bx3fuoiA+ConTNePbz2+1vsv+7F3Zg==@kvack.org X-Gm-Message-State: AOJu0YwXNpHPL9CvfDxWGETxbkVBdKdnroPcpKSHgZZDZiE28/ggC1u4 8njk9GFjeIBVQ39bUxcgHHIoy2BUjDFemgo6PjzwPGz+Rjbpv5eO0psMK/ddDqPBs1HXVEFwWw= = X-Google-Smtp-Source: AGHT+IGbzRLPDDV73rxMsaRerWBWjkFmSiW+9snF6eGB9z04UAhCgCAjBT3TYQ4Timp1oFUP+R5pRnwAyg== X-Received: from wmbgx13.prod.google.com ([2002:a05:600c:858d:b0:43d:1d5b:1c79]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:4690:b0:43c:ec28:d303 with SMTP id 5b1f17b1804b1-43d3b950aefmr32213585e9.5.1742314850210; Tue, 18 Mar 2025 09:20:50 -0700 (PDT) Date: Tue, 18 Mar 2025 16:20:40 +0000 In-Reply-To: <20250318162046.4016367-1-tabba@google.com> Mime-Version: 1.0 References: <20250318162046.4016367-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.rc1.451.g8f38331e32-goog Message-ID: <20250318162046.4016367-2-tabba@google.com> Subject: [PATCH v6 1/7] KVM: guest_memfd: Make guest mem use guest mem inodes instead of anonymous inodes From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org Cc: 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, xiaoyao.li@intel.com, 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, david@redhat.com, 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, tabba@google.com X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: CF5D1120006 X-Stat-Signature: 7na73x7qfb8fzpct5izscdatacqpdwun X-HE-Tag: 1742314851-990982 X-HE-Meta: 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 lqlglPRf 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 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: Ackerley Tng Using guest mem inodes allows us to store metadata for the backing memory on the inode. Metadata will be added in a later patch to support HugeTLB pages. Metadata about backing memory should not be stored on the file, since the file represents a guest_memfd's binding with a struct kvm, and metadata about backing memory is not unique to a specific binding and struct kvm. Signed-off-by: Fuad Tabba Signed-off-by: Ackerley Tng --- include/uapi/linux/magic.h | 1 + virt/kvm/guest_memfd.c | 130 +++++++++++++++++++++++++++++++------ 2 files changed, 111 insertions(+), 20 deletions(-) diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index bb575f3ab45e..169dba2a6920 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -103,5 +103,6 @@ #define DEVMEM_MAGIC 0x454d444d /* "DMEM" */ #define SECRETMEM_MAGIC 0x5345434d /* "SECM" */ #define PID_FS_MAGIC 0x50494446 /* "PIDF" */ +#define GUEST_MEMORY_MAGIC 0x474d454d /* "GMEM" */ #endif /* __LINUX_MAGIC_H__ */ diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index fbf89e643add..844e70c82558 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -1,12 +1,16 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include +#include #include #include #include "kvm_mm.h" +static struct vfsmount *kvm_gmem_mnt; + struct kvm_gmem { struct kvm *kvm; struct xarray bindings; @@ -320,6 +324,38 @@ static pgoff_t kvm_gmem_get_index(struct kvm_memory_slot *slot, gfn_t gfn) return gfn - slot->base_gfn + slot->gmem.pgoff; } +static const struct super_operations kvm_gmem_super_operations = { + .statfs = simple_statfs, +}; + +static int kvm_gmem_init_fs_context(struct fs_context *fc) +{ + struct pseudo_fs_context *ctx; + + if (!init_pseudo(fc, GUEST_MEMORY_MAGIC)) + return -ENOMEM; + + ctx = fc->fs_private; + ctx->ops = &kvm_gmem_super_operations; + + return 0; +} + +static struct file_system_type kvm_gmem_fs = { + .name = "kvm_guest_memory", + .init_fs_context = kvm_gmem_init_fs_context, + .kill_sb = kill_anon_super, +}; + +static void kvm_gmem_init_mount(void) +{ + kvm_gmem_mnt = kern_mount(&kvm_gmem_fs); + BUG_ON(IS_ERR(kvm_gmem_mnt)); + + /* For giggles. Userspace can never map this anyways. */ + kvm_gmem_mnt->mnt_flags |= MNT_NOEXEC; +} + #ifdef CONFIG_KVM_GMEM_SHARED_MEM static bool kvm_gmem_offset_is_shared(struct file *file, pgoff_t index) { @@ -430,6 +466,8 @@ static struct file_operations kvm_gmem_fops = { void kvm_gmem_init(struct module *module) { kvm_gmem_fops.owner = module; + + kvm_gmem_init_mount(); } static int kvm_gmem_migrate_folio(struct address_space *mapping, @@ -511,11 +549,79 @@ static const struct inode_operations kvm_gmem_iops = { .setattr = kvm_gmem_setattr, }; +static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, + loff_t size, u64 flags) +{ + const struct qstr qname = QSTR_INIT(name, strlen(name)); + struct inode *inode; + int err; + + inode = alloc_anon_inode(kvm_gmem_mnt->mnt_sb); + if (IS_ERR(inode)) + return inode; + + err = security_inode_init_security_anon(inode, &qname, NULL); + if (err) { + iput(inode); + return ERR_PTR(err); + } + + inode->i_private = (void *)(unsigned long)flags; + inode->i_op = &kvm_gmem_iops; + inode->i_mapping->a_ops = &kvm_gmem_aops; + inode->i_mode |= S_IFREG; + inode->i_size = size; + mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); + mapping_set_inaccessible(inode->i_mapping); + /* Unmovable mappings are supposed to be marked unevictable as well. */ + WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping)); + + return inode; +} + +static struct file *kvm_gmem_inode_create_getfile(void *priv, loff_t size, + u64 flags) +{ + static const char *name = "[kvm-gmem]"; + struct inode *inode; + struct file *file; + int err; + + err = -ENOENT; + if (!try_module_get(kvm_gmem_fops.owner)) + goto err; + + inode = kvm_gmem_inode_make_secure_inode(name, size, flags); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + goto err_put_module; + } + + file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR, + &kvm_gmem_fops); + if (IS_ERR(file)) { + err = PTR_ERR(file); + goto err_put_inode; + } + + file->f_flags |= O_LARGEFILE; + file->private_data = priv; + +out: + return file; + +err_put_inode: + iput(inode); +err_put_module: + module_put(kvm_gmem_fops.owner); +err: + file = ERR_PTR(err); + goto out; +} + static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) { - const char *anon_name = "[kvm-gmem]"; struct kvm_gmem *gmem; - struct inode *inode; struct file *file; int fd, err; @@ -529,32 +635,16 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) goto err_fd; } - file = anon_inode_create_getfile(anon_name, &kvm_gmem_fops, gmem, - O_RDWR, NULL); + file = kvm_gmem_inode_create_getfile(gmem, size, flags); if (IS_ERR(file)) { err = PTR_ERR(file); goto err_gmem; } - file->f_flags |= O_LARGEFILE; - - inode = file->f_inode; - WARN_ON(file->f_mapping != inode->i_mapping); - - inode->i_private = (void *)(unsigned long)flags; - inode->i_op = &kvm_gmem_iops; - inode->i_mapping->a_ops = &kvm_gmem_aops; - inode->i_mode |= S_IFREG; - inode->i_size = size; - mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); - mapping_set_inaccessible(inode->i_mapping); - /* Unmovable mappings are supposed to be marked unevictable as well. */ - WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping)); - kvm_get_kvm(kvm); gmem->kvm = kvm; xa_init(&gmem->bindings); - list_add(&gmem->entry, &inode->i_mapping->i_private_list); + list_add(&gmem->entry, &file_inode(file)->i_mapping->i_private_list); fd_install(fd, file); return fd;