Add dedicated inode structure (kvm_gmem_inode_info) and slab-allocated inode cache for guest memory backing, similar to how shmem handles inodes.
This adds the necessary allocation/destruction functions and prepares for upcoming guest_memfd NUMA policy support changes.
Signed-off-by: Shivank Garg shivankg@amd.com --- virt/kvm/guest_memfd.c | 70 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 68 insertions(+), 2 deletions(-)
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 6c66a0974055..356947d36a47 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -17,6 +17,15 @@ struct kvm_gmem { struct list_head entry; };
+struct kvm_gmem_inode_info { + struct inode vfs_inode; +}; + +static inline struct kvm_gmem_inode_info *KVM_GMEM_I(struct inode *inode) +{ + return container_of(inode, struct kvm_gmem_inode_info, vfs_inode); +} + /** * folio_file_pfn - like folio_file_page, but return a pfn. * @folio: The folio which contains this index. @@ -389,13 +398,46 @@ static struct file_operations kvm_gmem_fops = { .fallocate = kvm_gmem_fallocate, };
+static struct kmem_cache *kvm_gmem_inode_cachep; + +static struct inode *kvm_gmem_alloc_inode(struct super_block *sb) +{ + struct kvm_gmem_inode_info *info; + + info = alloc_inode_sb(sb, kvm_gmem_inode_cachep, GFP_KERNEL); + if (!info) + return NULL; + + return &info->vfs_inode; +} + +static void kvm_gmem_destroy_inode(struct inode *inode) +{ +} + +static void kvm_gmem_free_inode(struct inode *inode) +{ + kmem_cache_free(kvm_gmem_inode_cachep, KVM_GMEM_I(inode)); +} + +static const struct super_operations kvm_gmem_super_operations = { + .statfs = simple_statfs, + .alloc_inode = kvm_gmem_alloc_inode, + .destroy_inode = kvm_gmem_destroy_inode, + .free_inode = kvm_gmem_free_inode, +}; + static int kvm_gmem_init_fs_context(struct fs_context *fc) { + struct pseudo_fs_context *ctx; + if (!init_pseudo(fc, GUEST_MEMFD_MAGIC)) return -ENOMEM;
fc->s_iflags |= SB_I_NOEXEC; fc->s_iflags |= SB_I_NODEV; + ctx = fc->fs_private; + ctx->ops = &kvm_gmem_super_operations;
return 0; } @@ -417,17 +459,41 @@ static int kvm_gmem_init_mount(void) return 0; }
+static void kvm_gmem_init_inode(void *foo) +{ + struct kvm_gmem_inode_info *info = foo; + + inode_init_once(&info->vfs_inode); +} + int kvm_gmem_init(struct module *module) { - kvm_gmem_fops.owner = module; + int ret; + struct kmem_cache_args args = { + .align = 0, + .ctor = kvm_gmem_init_inode, + };
- return kvm_gmem_init_mount(); + kvm_gmem_fops.owner = module; + kvm_gmem_inode_cachep = kmem_cache_create("kvm_gmem_inode_cache", + sizeof(struct kvm_gmem_inode_info), + &args, SLAB_ACCOUNT); + if (!kvm_gmem_inode_cachep) + return -ENOMEM; + ret = kvm_gmem_init_mount(); + if (ret) { + kmem_cache_destroy(kvm_gmem_inode_cachep); + return ret; + } + return 0; }
void kvm_gmem_exit(void) { kern_unmount(kvm_gmem_mnt); kvm_gmem_mnt = NULL; + rcu_barrier(); + kmem_cache_destroy(kvm_gmem_inode_cachep); }
static int kvm_gmem_migrate_folio(struct address_space *mapping,