From patchwork Thu Oct 10 08:59:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fuad Tabba X-Patchwork-Id: 834216 Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) (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 5F74B1C3310 for ; Thu, 10 Oct 2024 08:59:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728550779; cv=none; b=YvJm2YQ8vVbh7fjgkz4eGlzkJQ9q5obH8jSr7uXNXAGGykRoF6tzC2i/0TzWoG427+7waYbWV6JH4g5JK4iPGQFvHnSJwLAWaAI8eQ+jcxt0Ycl0kOdGwNwWVH3lg9oktb4mA2GEUtr9TgHpcLfl4WXi0WfjWnKMRQeXtISA/yM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728550779; c=relaxed/simple; bh=Mga7mt3X9arSdqCQlXB1u30FTNDLBjy3at6GjGP0Jvo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=WEtkRW4KWDxJVns+Mmi7GscRvX1zohH3uIe70moW4LLpqFAwikFZh3D1d00wIRfarnT9zygki1AdYaP2ZVWi7QN1LdtP2hxV1HjTmN5SHVmp6g2Ui3DV64Pjghgs1o6xFugkVDGsGsVedXDHWFdt9OE5jvOhz03qhq8GLwIF4zk= 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=2CHS9tF7; arc=none smtp.client-ip=209.85.221.74 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="2CHS9tF7" Received: by mail-wr1-f74.google.com with SMTP id ffacd0b85a97d-37d4922d8c7so201342f8f.1 for ; Thu, 10 Oct 2024 01:59:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1728550776; x=1729155576; 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=Vyku6e6IRAvv3Cnewk6FjoCA5VWGrQWG+Ki8Kqf1epQ=; b=2CHS9tF7jEriErxosQt3e4Mw6EAy/zXh6yCm7fpWVTWdUa5SyGHEctI75KDz5yjjWT qpjLF9xRlTyYeDKXjZaGW7kcQ663TPyJ6gtBQXIJCh3az+oIYGQWlnY2TRKn79vbJEUk 68uARHp6UImIMe+ooa9pULVCEMBW5OEnMdU4PmBy8/EioZ1Lkzl1Nlt35oyr+LhDeYGL JpJwXG4/cDElszjAuGLTMGznUyoVmRe7gsub0qntc0Si64OQ5OxFMLf9QXmWM7YrbHyM 144c7/hncZIcyZcxYM4YvK4ASWNK0yaLhVv6LTPf9zT6QHfqazPKteGW3MMdRBmGA+jW WC2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728550776; x=1729155576; 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=Vyku6e6IRAvv3Cnewk6FjoCA5VWGrQWG+Ki8Kqf1epQ=; b=UWyIsK2YspL0IUYW9+FCDe31m/a6FKqIXByzHQloySAfKKY99rUVsVCUjd3K8jaIMT Q4Aq6i5cjHD92OyGntmG0FS+cN/cRtH7Xf6gh2TGBHDpJgjBxSxypgXCeSasx0yYirAa EK7UFIS+52x58fvqWUbrhGYkGb62nVXmUKYdt01S8qrA66ocWC1OY7mn+wyCU9oeSXNb SMzvBt5h3Acw9nyYNBsr8+7o+Pq7N8Ts3tVZarZ4XwQSBVPRMtwiINaz1eXXurUPgOo5 T4dFNrS4TAzPUguFPJQ06CVGi1h62sTR59mkIYNL/R7GLlgqECTmL11/cPIcZEyE1riU tgKA== X-Forwarded-Encrypted: i=1; AJvYcCVWM8jVCVCbSbPw8sCuJzvhNYEicK6oQxQo9qIneWHUNcWjKAOLIW6GwFiJXsQ3daIiLSwir0beY5qu7wBc@vger.kernel.org X-Gm-Message-State: AOJu0YyvgvsvhOetqTdCobFmfoJwUTq2aKD6PBDvHiWDJ0NIHDg9AzF8 JDM0JnQ3T3IjEskgmhtfWhFaQ9kfMoYyADIub46AjnuzFrtDoFwngVyI9bQ7HHhtSK+aQ43iMw= = X-Google-Smtp-Source: AGHT+IGSZpfTUz1T03Ghz7pMPW+WsgsV7vYF/u4tI/gDmrDsGEArgV4hEd1O0Gy7y58cVD5g/Q9cGyXW2w== X-Received: from fuad.c.googlers.com ([fda3:e722:ac3:cc00:28:9cb1:c0a8:1613]) (user=tabba job=sendgmr) by 2002:adf:ed10:0:b0:37d:4332:e91a with SMTP id ffacd0b85a97d-37d4332ea66mr2783f8f.0.1728550775123; Thu, 10 Oct 2024 01:59:35 -0700 (PDT) Date: Thu, 10 Oct 2024 09:59:20 +0100 In-Reply-To: <20241010085930.1546800-1-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: <20241010085930.1546800-1-tabba@google.com> X-Mailer: git-send-email 2.47.0.rc0.187.ge670bccf7e-goog Message-ID: <20241010085930.1546800-2-tabba@google.com> Subject: [PATCH v3 01/11] 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, yu.c.zhang@linux.intel.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, 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: Ackerley Tng Signed-off-by: Fuad Tabba --- include/uapi/linux/magic.h | 1 + virt/kvm/guest_memfd.c | 119 ++++++++++++++++++++++++++++++------- 2 files changed, 100 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 8f079a61a56d..5d7fd1f708a6 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -1,12 +1,17 @@ // SPDX-License-Identifier: GPL-2.0 +#include +#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; @@ -302,6 +307,38 @@ static inline struct file *kvm_gmem_get_file(struct kvm_memory_slot *slot) return get_file_active(&slot->gmem.file); } +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; +} + static struct file_operations kvm_gmem_fops = { .open = generic_file_open, .release = kvm_gmem_release, @@ -311,6 +348,8 @@ 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, @@ -392,11 +431,67 @@ 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; + + if (kvm_gmem_fops.owner && !try_module_get(kvm_gmem_fops.owner)) + return ERR_PTR(-ENOENT); + + inode = kvm_gmem_inode_make_secure_inode(name, size, flags); + if (IS_ERR(inode)) + return ERR_CAST(inode); + + file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR, + &kvm_gmem_fops); + if (IS_ERR(file)) { + iput(inode); + return file; + } + + file->f_mapping = inode->i_mapping; + file->f_flags |= O_LARGEFILE; + file->private_data = priv; + + return file; +} + 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; @@ -410,32 +505,16 @@ 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;