diff options
| -rw-r--r-- | include/uapi/linux/magic.h | 1 | ||||
| -rw-r--r-- | virt/kvm/guest_memfd.c | 82 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 7 | ||||
| -rw-r--r-- | virt/kvm/kvm_mm.h | 9 |
4 files changed, 80 insertions, 19 deletions
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h index bb575f3ab45e..638ca21b7a90 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_MEMFD_MAGIC 0x474d454d /* "GMEM" */ #endif /* __LINUX_MAGIC_H__ */ diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 5cce20ff418d..ce04fc85e631 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -1,12 +1,16 @@ // SPDX-License-Identifier: GPL-2.0 +#include <linux/anon_inodes.h> #include <linux/backing-dev.h> #include <linux/falloc.h> +#include <linux/fs.h> #include <linux/kvm_host.h> +#include <linux/pseudo_fs.h> #include <linux/pagemap.h> -#include <linux/anon_inodes.h> #include "kvm_mm.h" +static struct vfsmount *kvm_gmem_mnt; + /* * A guest_memfd instance can be associated multiple VMs, each with its own * "view" of the underlying physical memory. @@ -424,11 +428,6 @@ static struct file_operations kvm_gmem_fops = { .fallocate = kvm_gmem_fallocate, }; -void kvm_gmem_init(struct module *module) -{ - kvm_gmem_fops.owner = module; -} - static int kvm_gmem_migrate_folio(struct address_space *mapping, struct folio *dst, struct folio *src, enum migrate_mode mode) @@ -500,7 +499,7 @@ bool __weak kvm_arch_supports_gmem_init_shared(struct kvm *kvm) static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) { - const char *anon_name = "[kvm-gmem]"; + static const char *name = "[kvm-gmem]"; struct gmem_file *f; struct inode *inode; struct file *file; @@ -516,16 +515,17 @@ 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, f, O_RDWR, NULL); - if (IS_ERR(file)) { - err = PTR_ERR(file); + /* __fput() will take care of fops_put(). */ + if (!fops_get(&kvm_gmem_fops)) { + err = -ENOENT; goto err_gmem; } - file->f_flags |= O_LARGEFILE; - - inode = file->f_inode; - WARN_ON(file->f_mapping != inode->i_mapping); + inode = anon_inode_make_secure_inode(kvm_gmem_mnt->mnt_sb, name, NULL); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + goto err_fops; + } inode->i_private = (void *)(unsigned long)flags; inode->i_op = &kvm_gmem_iops; @@ -537,6 +537,15 @@ 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)); + file = alloc_file_pseudo(inode, kvm_gmem_mnt, name, O_RDWR, &kvm_gmem_fops); + if (IS_ERR(file)) { + err = PTR_ERR(file); + goto err_inode; + } + + file->f_flags |= O_LARGEFILE; + file->private_data = f; + kvm_get_kvm(kvm); f->kvm = kvm; xa_init(&f->bindings); @@ -545,6 +554,10 @@ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags) fd_install(fd, file); return fd; +err_inode: + iput(inode); +err_fops: + fops_put(&kvm_gmem_fops); err_gmem: kfree(f); err_fd: @@ -816,3 +829,44 @@ put_folio_and_exit: } EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_populate); #endif + +static int kvm_gmem_init_fs_context(struct fs_context *fc) +{ + if (!init_pseudo(fc, GUEST_MEMFD_MAGIC)) + return -ENOMEM; + + fc->s_iflags |= SB_I_NOEXEC; + fc->s_iflags |= SB_I_NODEV; + + return 0; +} + +static struct file_system_type kvm_gmem_fs = { + .name = "guest_memfd", + .init_fs_context = kvm_gmem_init_fs_context, + .kill_sb = kill_anon_super, +}; + +static int kvm_gmem_init_mount(void) +{ + kvm_gmem_mnt = kern_mount(&kvm_gmem_fs); + + if (IS_ERR(kvm_gmem_mnt)) + return PTR_ERR(kvm_gmem_mnt); + + kvm_gmem_mnt->mnt_flags |= MNT_NOEXEC; + return 0; +} + +int kvm_gmem_init(struct module *module) +{ + kvm_gmem_fops.owner = module; + + return kvm_gmem_init_mount(); +} + +void kvm_gmem_exit(void) +{ + kern_unmount(kvm_gmem_mnt); + kvm_gmem_mnt = NULL; +} diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index b7a0ae2a7b20..4845e5739436 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -6517,7 +6517,9 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module) if (WARN_ON_ONCE(r)) goto err_vfio; - kvm_gmem_init(module); + r = kvm_gmem_init(module); + if (r) + goto err_gmem; r = kvm_init_virtualization(); if (r) @@ -6538,6 +6540,8 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module) err_register: kvm_uninit_virtualization(); err_virt: + kvm_gmem_exit(); +err_gmem: kvm_vfio_ops_exit(); err_vfio: kvm_async_pf_deinit(); @@ -6569,6 +6573,7 @@ void kvm_exit(void) for_each_possible_cpu(cpu) free_cpumask_var(per_cpu(cpu_kick_mask, cpu)); kmem_cache_destroy(kvm_vcpu_cache); + kvm_gmem_exit(); kvm_vfio_ops_exit(); kvm_async_pf_deinit(); kvm_irqfd_exit(); diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h index 31defb08ccba..9fcc5d5b7f8d 100644 --- a/virt/kvm/kvm_mm.h +++ b/virt/kvm/kvm_mm.h @@ -68,17 +68,18 @@ static inline void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, #endif /* HAVE_KVM_PFNCACHE */ #ifdef CONFIG_KVM_GUEST_MEMFD -void kvm_gmem_init(struct module *module); +int kvm_gmem_init(struct module *module); +void kvm_gmem_exit(void); int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args); int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, unsigned int fd, loff_t offset); void kvm_gmem_unbind(struct kvm_memory_slot *slot); #else -static inline void kvm_gmem_init(struct module *module) +static inline int kvm_gmem_init(struct module *module) { - + return 0; } - +static inline void kvm_gmem_exit(void) {}; static inline int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, unsigned int fd, loff_t offset) |