From patchwork Fri Mar 28 15:31:27 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fuad Tabba X-Patchwork-Id: 14032180 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (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 9A3EA1E4AE for ; Fri, 28 Mar 2025 15:31:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743175900; cv=none; b=fSgTaauzxhuSyAWL3NQQBXADhQaVO1PkXX8e8v2oHlnB70rA1F91TjN/Yv4aNpRLg8cItSZ52cvqJRHOLAs6N++lzk43udBtEhSvgxBL8HC7HgofQKesn5CDzOz7VY83pUvsp+b3pMj/IqY9f93HvWG09UjBjI90LB4CMl6SFsE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743175900; c=relaxed/simple; bh=/DbJqIf5jARzMrFbUI/9YBIhv5OcRrzbdxbR00O3bKo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=eNYj+O3c6GTLGvpVz73QuH0E6FVR7HdnJhVBS+ty+7ER/wgCsBrGETV/qJ2iocdNsndEV0KMjJRB8gWhuO2xOm/wJrpgzB4G6JFl6cAmhmPRv+jvghwLSGQi32hhNeS7/mEGYz16OE5xU5q6veIHqVsJQIppHiNlSjHTvAfmT+8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=FoJwqyne; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="FoJwqyne" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-43bd0586b86so13880695e9.3 for ; Fri, 28 Mar 2025 08:31:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1743175897; x=1743780697; darn=vger.kernel.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=pob1TR9dEqi7MIBnWCqwy033V3I8qaqnlKaqyDYFuI0=; b=FoJwqyneD4NHahCGtNSatjczyFolhh5y3whqWvGV6Ezk0CIB8VJnBx+4IQg5xyX+Nu j3lFO0Dy6hV8aa5lhQqXYQF3JbaXjkBDTgmb/TOmBXPUoQzDx07VHxTeCeo8H++XNPGH WT1WwNY9PDPfTfkMPnrcp3ZL33HjeUHndQP/QV9pffa7sAQj1/xxUFce5rvFyxTNie9+ 64KHcxVaaSfBB7/h0tBabCNZZj3+AONCRZJF7P4SHrzhIUjwpESB6ya8+DYOUFbp2csG qT9jZbCpNZNnvTfiUpP9ugvOxhRL0XOLfpP+AjQgrqUEzAIkc1MoKsVx9FwwgmMRCIe4 +wZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743175897; x=1743780697; 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=pob1TR9dEqi7MIBnWCqwy033V3I8qaqnlKaqyDYFuI0=; b=qJxxTb9Tn/LS6uqw3XOLwxL1Icu0mNeIbT9pQZOFUEbKnnrVnoYtni4JPZDSWB3UZd GpmcB/LmIlvvyDMXjQTMLpAj/6kXTCL4P2h8opipinuKXr4wmB2NLC9WNqWMQtJyRXEd /8R5dhCJCaTGjKQKr0MIQgHjSu6koggVBaNB76HW4SCj1QjTrKwoGDpYAEaG59G7BOQ+ /69UMY1dY8Exq1lwXoVZJNT7lsRv5/YHnTEC3Wrqop2+bwSowPw/0oaJLhLhOz6mVWN7 o/Sk2TD7AEIyT0WZtvknoPVd9sBhKHA1MWOKjpa55ESi6xFLh/DHqUEGjZ9Pl2UcoOoE g0jA== X-Forwarded-Encrypted: i=1; AJvYcCVrtuTXloL8Yh4jR1ol5D2JnqcGxV1i+MGmuJiNb4H1/D5wKbO8UUQC/ccHYkNAuLBZAvKBVPM1nw1dC+UM@vger.kernel.org X-Gm-Message-State: AOJu0Yy8dYyetqEBnrXSK9BZYhaYekTRxnTPTnbtHuIteXS+4n7c7wDX T8lasq9V2JiOib4ecPOtXSpk6Eg+ux6BR56BzHMOxmPz0X0EfFRI7oyD0fRoo3iLE3rKIpUkLw= = X-Google-Smtp-Source: AGHT+IGngaZfLNR9G+mSoTgx2073MmGnWMrkl6EslGCWKeowY0DzmJkEF+mR9oXw1GyqKOgR3dKkpwK4uw== X-Received: from wmbay1.prod.google.com ([2002:a05:600c:1e01:b0:43d:9f1:31a9]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:c15:b0:43c:eeee:b713 with SMTP id 5b1f17b1804b1-43d85065ab9mr84209735e9.20.1743175897006; Fri, 28 Mar 2025 08:31:37 -0700 (PDT) Date: Fri, 28 Mar 2025 15:31:27 +0000 In-Reply-To: <20250328153133.3504118-1-tabba@google.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250328153133.3504118-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.472.ge94155a9ec-goog Message-ID: <20250328153133.3504118-2-tabba@google.com> Subject: [PATCH v7 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, pankaj.gupta@amd.com, tabba@google.com 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;