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charset="UTF-8" X-Stat-Signature: ce9sjbyxpwuqax5rpm1rjtib4gtor8ms X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 6C1EFA0008 X-HE-Tag: 1747266181-312252 X-HE-Meta: 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 MoQ3p/o+ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Track guest_memfd memory's shareability status within the inode as opposed to the file, since it is property of the guest_memfd's memory contents. Shareability is a property of the memory and is indexed using the page's index in the inode. Because shareability is the memory's property, it is stored within guest_memfd instead of within KVM, like in kvm->mem_attr_array. KVM_MEMORY_ATTRIBUTE_PRIVATE in kvm->mem_attr_array must still be retained to allow VMs to only use guest_memfd for private memory and some other memory for shared memory. Not all use cases require guest_memfd() to be shared with the host when first created. Add a new flag, GUEST_MEMFD_FLAG_INIT_PRIVATE, which when set on KVM_CREATE_GUEST_MEMFD, initializes the memory as private to the guest, and therefore not mappable by the host. Otherwise, memory is shared until explicitly converted to private. Signed-off-by: Ackerley Tng Co-developed-by: Vishal Annapurve Signed-off-by: Vishal Annapurve Co-developed-by: Fuad Tabba Signed-off-by: Fuad Tabba Change-Id: If03609cbab3ad1564685c85bdba6dcbb6b240c0f --- Documentation/virt/kvm/api.rst | 5 ++ include/uapi/linux/kvm.h | 2 + virt/kvm/guest_memfd.c | 124 ++++++++++++++++++++++++++++++++- 3 files changed, 129 insertions(+), 2 deletions(-) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 86f74ce7f12a..f609337ae1c2 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6408,6 +6408,11 @@ belonging to the slot via its userspace_addr. The use of GUEST_MEMFD_FLAG_SUPPORT_SHARED will not be allowed for CoCo VMs. This is validated when the guest_memfd instance is bound to the VM. +If the capability KVM_CAP_GMEM_CONVERSIONS is supported, then the 'flags' field +supports GUEST_MEMFD_FLAG_INIT_PRIVATE. Setting GUEST_MEMFD_FLAG_INIT_PRIVATE +will initialize the memory for the guest_memfd as guest-only and not faultable +by the host. + See KVM_SET_USER_MEMORY_REGION2 for additional details. 4.143 KVM_PRE_FAULT_MEMORY diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4cc824a3a7c9..d7df312479aa 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1567,7 +1567,9 @@ struct kvm_memory_attributes { #define KVM_MEMORY_ATTRIBUTE_PRIVATE (1ULL << 3) #define KVM_CREATE_GUEST_MEMFD _IOWR(KVMIO, 0xd4, struct kvm_create_guest_memfd) + #define GUEST_MEMFD_FLAG_SUPPORT_SHARED (1UL << 0) +#define GUEST_MEMFD_FLAG_INIT_PRIVATE (1UL << 1) struct kvm_create_guest_memfd { __u64 size; diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 239d0f13dcc1..590932499eba 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -4,6 +4,7 @@ #include #include #include +#include #include #include @@ -17,6 +18,24 @@ struct kvm_gmem { struct list_head entry; }; +struct kvm_gmem_inode_private { +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + struct maple_tree shareability; +#endif +}; + +enum shareability { + SHAREABILITY_GUEST = 1, /* Only the guest can map (fault) folios in this range. */ + SHAREABILITY_ALL = 2, /* Both guest and host can fault folios in this range. */ +}; + +static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index); + +static struct kvm_gmem_inode_private *kvm_gmem_private(struct inode *inode) +{ + return inode->i_mapping->i_private_data; +} + /** * folio_file_pfn - like folio_file_page, but return a pfn. * @folio: The folio which contains this index. @@ -29,6 +48,58 @@ static inline kvm_pfn_t folio_file_pfn(struct folio *folio, pgoff_t index) return folio_pfn(folio) + (index & (folio_nr_pages(folio) - 1)); } +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + +static int kvm_gmem_shareability_setup(struct kvm_gmem_inode_private *private, + loff_t size, u64 flags) +{ + enum shareability m; + pgoff_t last; + + last = (size >> PAGE_SHIFT) - 1; + m = flags & GUEST_MEMFD_FLAG_INIT_PRIVATE ? SHAREABILITY_GUEST : + SHAREABILITY_ALL; + return mtree_store_range(&private->shareability, 0, last, xa_mk_value(m), + GFP_KERNEL); +} + +static enum shareability kvm_gmem_shareability_get(struct inode *inode, + pgoff_t index) +{ + struct maple_tree *mt; + void *entry; + + mt = &kvm_gmem_private(inode)->shareability; + entry = mtree_load(mt, index); + WARN(!entry, + "Shareability should always be defined for all indices in inode."); + + return xa_to_value(entry); +} + +static struct folio *kvm_gmem_get_shared_folio(struct inode *inode, pgoff_t index) +{ + if (kvm_gmem_shareability_get(inode, index) != SHAREABILITY_ALL) + return ERR_PTR(-EACCES); + + return kvm_gmem_get_folio(inode, index); +} + +#else + +static int kvm_gmem_shareability_setup(struct maple_tree *mt, loff_t size, u64 flags) +{ + return 0; +} + +static inline struct folio *kvm_gmem_get_shared_folio(struct inode *inode, pgoff_t index) +{ + WARN_ONCE("Unexpected call to get shared folio.") + return NULL; +} + +#endif /* CONFIG_KVM_GMEM_SHARED_MEM */ + static int __kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot, pgoff_t index, struct folio *folio) { @@ -333,7 +404,7 @@ static vm_fault_t kvm_gmem_fault_shared(struct vm_fault *vmf) filemap_invalidate_lock_shared(inode->i_mapping); - folio = kvm_gmem_get_folio(inode, vmf->pgoff); + folio = kvm_gmem_get_shared_folio(inode, vmf->pgoff); if (IS_ERR(folio)) { int err = PTR_ERR(folio); @@ -420,8 +491,33 @@ static struct file_operations kvm_gmem_fops = { .fallocate = kvm_gmem_fallocate, }; +static void kvm_gmem_free_inode(struct inode *inode) +{ + struct kvm_gmem_inode_private *private = kvm_gmem_private(inode); + + kfree(private); + + free_inode_nonrcu(inode); +} + +static void kvm_gmem_destroy_inode(struct inode *inode) +{ + struct kvm_gmem_inode_private *private = kvm_gmem_private(inode); + +#ifdef CONFIG_KVM_GMEM_SHARED_MEM + /* + * mtree_destroy() can't be used within rcu callback, hence can't be + * done in ->free_inode(). + */ + if (private) + mtree_destroy(&private->shareability); +#endif +} + static const struct super_operations kvm_gmem_super_operations = { .statfs = simple_statfs, + .destroy_inode = kvm_gmem_destroy_inode, + .free_inode = kvm_gmem_free_inode, }; static int kvm_gmem_init_fs_context(struct fs_context *fc) @@ -549,12 +645,26 @@ static const struct inode_operations kvm_gmem_iops = { static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, loff_t size, u64 flags) { + struct kvm_gmem_inode_private *private; struct inode *inode; + int err; inode = alloc_anon_secure_inode(kvm_gmem_mnt->mnt_sb, name); if (IS_ERR(inode)) return inode; + err = -ENOMEM; + private = kzalloc(sizeof(*private), GFP_KERNEL); + if (!private) + goto out; + + mt_init(&private->shareability); + inode->i_mapping->i_private_data = private; + + err = kvm_gmem_shareability_setup(private, size, flags); + if (err) + goto out; + inode->i_private = (void *)(unsigned long)flags; inode->i_op = &kvm_gmem_iops; inode->i_mapping->a_ops = &kvm_gmem_aops; @@ -566,6 +676,11 @@ static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping)); return inode; + +out: + iput(inode); + + return ERR_PTR(err); } static struct file *kvm_gmem_inode_create_getfile(void *priv, loff_t size, @@ -654,6 +769,9 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) if (kvm_arch_vm_supports_gmem_shared_mem(kvm)) valid_flags |= GUEST_MEMFD_FLAG_SUPPORT_SHARED; + if (flags & GUEST_MEMFD_FLAG_SUPPORT_SHARED) + valid_flags |= GUEST_MEMFD_FLAG_INIT_PRIVATE; + if (flags & ~valid_flags) return -EINVAL; @@ -842,6 +960,8 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, if (!file) return -EFAULT; + filemap_invalidate_lock_shared(file_inode(file)->i_mapping); + folio = __kvm_gmem_get_pfn(file, slot, index, pfn, &is_prepared, max_order); if (IS_ERR(folio)) { r = PTR_ERR(folio); @@ -857,8 +977,8 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, *page = folio_file_page(folio, index); else folio_put(folio); - out: + filemap_invalidate_unlock_shared(file_inode(file)->i_mapping); fput(file); return r; } -- 2.49.0.1045.g170613ef41-goog