From nobody Sun Feb 8 18:04:13 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27E13E732FD for ; Thu, 28 Sep 2023 18:07:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231617AbjI1SHt (ORCPT ); Thu, 28 Sep 2023 14:07:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229581AbjI1SHr (ORCPT ); Thu, 28 Sep 2023 14:07:47 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D094ADD for ; Thu, 28 Sep 2023 11:06:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695924416; h=from:from: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:content-transfer-encoding; bh=W2Qgpx+gPcVi5iw6zaPVN+JMZ4nnFY6HftGrYu1Yym0=; b=PoNZABAcfDf7LYJE9JGqBIY94AEieYLpjOQslxnRdNVlt+G3elPcnEop9+PT/eleRDkSYJ u/tqjjr00KZ5m7a9rQ2Yxw6rnppnjvq2O/iWi49IRTv12zigoj1JpZ/WXm0CWDPBgTKmIG gMn6efk45NzUk2enJKGAL3USw5Fu7iA= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-668-4YkjJcL7OQmrDNyzn_vVhQ-1; Thu, 28 Sep 2023 14:06:52 -0400 X-MC-Unique: 4YkjJcL7OQmrDNyzn_vVhQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 42EBC29AA386; Thu, 28 Sep 2023 18:06:52 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2266D140273C; Thu, 28 Sep 2023 18:06:52 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: seanjc@google.com Subject: [PATCH gmem FIXUP] kvm: guestmem: do not use a file system Date: Thu, 28 Sep 2023 14:06:51 -0400 Message-Id: <20230928180651.1525674-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Use a run-of-the-mill anonymous inode, there is nothing useful being provided by kvm_gmem_fs. Signed-off-by: Paolo Bonzini --- include/uapi/linux/magic.h | 1 - virt/kvm/guest_mem.c | 110 ++++++++++--------------------------- virt/kvm/kvm_main.c | 6 -- 3 files changed, 30 insertions(+), 87 deletions(-) diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index afe9c376c9a5..6325d1d0e90f 100644 --- a/include/uapi/linux/magic.h +++ b/include/uapi/linux/magic.h @@ -101,6 +101,5 @@ #define DMA_BUF_MAGIC 0x444d4142 /* "DMAB" */ #define DEVMEM_MAGIC 0x454d444d /* "DMEM" */ #define SECRETMEM_MAGIC 0x5345434d /* "SECM" */ -#define KVM_GUEST_MEMORY_MAGIC 0x474d454d /* "GMEM" */ =20 #endif /* __LINUX_MAGIC_H__ */ diff --git a/virt/kvm/guest_mem.c b/virt/kvm/guest_mem.c index a819367434e9..73b841a2e1b1 100644 --- a/virt/kvm/guest_mem.c +++ b/virt/kvm/guest_mem.c @@ -3,14 +3,10 @@ #include #include #include -#include - -#include +#include =20 #include "kvm_mm.h" =20 -static struct vfsmount *kvm_gmem_mnt; - struct kvm_gmem { struct kvm *kvm; struct xarray bindings; @@ -356,23 +352,40 @@ static const struct inode_operations kvm_gmem_iops = =3D { .setattr =3D kvm_gmem_setattr, }; =20 -static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags, - struct vfsmount *mnt) +static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) { const char *anon_name =3D "[kvm-gmem]"; - const struct qstr qname =3D QSTR_INIT(anon_name, strlen(anon_name)); struct kvm_gmem *gmem; struct inode *inode; struct file *file; int fd, err; =20 - inode =3D alloc_anon_inode(mnt->mnt_sb); - if (IS_ERR(inode)) - return PTR_ERR(inode); + fd =3D get_unused_fd_flags(0); + if (fd < 0) + return fd; =20 - err =3D security_inode_init_security_anon(inode, &qname, NULL); - if (err) - goto err_inode; + gmem =3D kzalloc(sizeof(*gmem), GFP_KERNEL); + if (!gmem) { + err =3D -ENOMEM; + goto err_fd; + } + + file =3D anon_inode_getfile(anon_name, &kvm_gmem_fops, gmem, + O_RDWR); + if (IS_ERR(file)) { + err =3D PTR_ERR(file); + goto err_gmem; + } + + file->f_flags |=3D O_LARGEFILE; + + kvm_get_kvm(kvm); + gmem->kvm =3D kvm; + xa_init(&gmem->bindings); + list_add(&gmem->entry, &file->f_mapping->private_list); + + inode =3D file->f_inode; + WARN_ON(file->f_mapping !=3D inode->i_mapping); =20 inode->i_private =3D (void *)(unsigned long)flags; inode->i_op =3D &kvm_gmem_iops; @@ -385,44 +398,13 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t = size, u64 flags, /* Unmovable mappings are supposed to be marked unevictable as well. */ WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping)); =20 - fd =3D get_unused_fd_flags(0); - if (fd < 0) { - err =3D fd; - goto err_inode; - } - - file =3D alloc_file_pseudo(inode, mnt, "kvm-gmem", O_RDWR, &kvm_gmem_fops= ); - if (IS_ERR(file)) { - err =3D PTR_ERR(file); - goto err_fd; - } - - file->f_flags |=3D O_LARGEFILE; - file->f_mapping =3D inode->i_mapping; - - gmem =3D kzalloc(sizeof(*gmem), GFP_KERNEL); - if (!gmem) { - err =3D -ENOMEM; - goto err_file; - } - - kvm_get_kvm(kvm); - gmem->kvm =3D kvm; - xa_init(&gmem->bindings); - - file->private_data =3D gmem; - - list_add(&gmem->entry, &inode->i_mapping->private_list); - fd_install(fd, file); return fd; =20 -err_file: - fput(file); +err_gmem: + kfree(gmem); err_fd: put_unused_fd(fd); -err_inode: - iput(inode); return err; } =20 @@ -455,7 +437,7 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_= guest_memfd *args) if (!kvm_gmem_is_valid_size(size, flags)) return -EINVAL; =20 - return __kvm_gmem_create(kvm, size, flags, kvm_gmem_mnt); + return __kvm_gmem_create(kvm, size, flags); } =20 int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, @@ -603,35 +585,3 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memor= y_slot *slot, return r; } EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn); - -static int kvm_gmem_init_fs_context(struct fs_context *fc) -{ - if (!init_pseudo(fc, KVM_GUEST_MEMORY_MAGIC)) - return -ENOMEM; - - return 0; -} - -static struct file_system_type kvm_gmem_fs =3D { - .name =3D "kvm_guest_memory", - .init_fs_context =3D kvm_gmem_init_fs_context, - .kill_sb =3D kill_anon_super, -}; - -int kvm_gmem_init(void) -{ - kvm_gmem_mnt =3D kern_mount(&kvm_gmem_fs); - if (IS_ERR(kvm_gmem_mnt)) - return PTR_ERR(kvm_gmem_mnt); - - /* For giggles. Userspace can never map this anyways. */ - kvm_gmem_mnt->mnt_flags |=3D MNT_NOEXEC; - - return 0; -} - -void kvm_gmem_exit(void) -{ - kern_unmount(kvm_gmem_mnt); - kvm_gmem_mnt =3D NULL; -} diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a83dfef1316e..4a1ded1faf84 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -6424,10 +6424,6 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align= , struct module *module) if (r) goto err_async_pf; =20 - r =3D kvm_gmem_init(); - if (r) - goto err_gmem; - kvm_chardev_ops.owner =3D module; =20 kvm_preempt_ops.sched_in =3D kvm_sched_in; @@ -6454,8 +6450,6 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align,= struct module *module) err_register: kvm_vfio_ops_exit(); err_vfio: - kvm_gmem_exit(); -err_gmem: kvm_async_pf_deinit(); err_async_pf: kvm_irqfd_exit(); --=20 2.39.1