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a63ca4236e
guest_memfd's inode represents memory the guest_memfd is providing. guest_memfd's file represents a struct kvm's view of that memory. Using a custom inode allows customization of the inode teardown process via callbacks. For example, ->evict_inode() allows customization of the truncation process on file close, and ->destroy_inode() and ->free_inode() allow customization of the inode freeing process. Customizing the truncation process allows flexibility in management of guest_memfd memory and customization of the inode freeing process allows proper cleanup of memory metadata stored on the inode. Memory metadata is more appropriately stored on the inode (as opposed to the file), since the metadata is for the memory and is not unique to a specific binding and struct kvm. Acked-by: David Hildenbrand <david@redhat.com> Co-developed-by: Fuad Tabba <tabba@google.com> Signed-off-by: Fuad Tabba <tabba@google.com> Signed-off-by: Ackerley Tng <ackerleytng@google.com> Signed-off-by: Shivank Garg <shivankg@amd.com> Tested-by: Ashish Kalra <ashish.kalra@amd.com> [sean: drop helpers, open code logic in __kvm_gmem_create()] Link: https://lore.kernel.org/r/20251016172853.52451-4-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
98 lines
2.7 KiB
C
98 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef __KVM_MM_H__
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#define __KVM_MM_H__ 1
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/*
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* Architectures can choose whether to use an rwlock or spinlock
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* for the mmu_lock. These macros, for use in common code
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* only, avoids using #ifdefs in places that must deal with
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* multiple architectures.
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*/
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#ifdef KVM_HAVE_MMU_RWLOCK
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#define KVM_MMU_LOCK_INIT(kvm) rwlock_init(&(kvm)->mmu_lock)
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#define KVM_MMU_LOCK(kvm) write_lock(&(kvm)->mmu_lock)
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#define KVM_MMU_UNLOCK(kvm) write_unlock(&(kvm)->mmu_lock)
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#else
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#define KVM_MMU_LOCK_INIT(kvm) spin_lock_init(&(kvm)->mmu_lock)
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#define KVM_MMU_LOCK(kvm) spin_lock(&(kvm)->mmu_lock)
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#define KVM_MMU_UNLOCK(kvm) spin_unlock(&(kvm)->mmu_lock)
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#endif /* KVM_HAVE_MMU_RWLOCK */
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struct kvm_follow_pfn {
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const struct kvm_memory_slot *slot;
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const gfn_t gfn;
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unsigned long hva;
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/* FOLL_* flags modifying lookup behavior, e.g. FOLL_WRITE. */
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unsigned int flags;
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/*
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* Pin the page (effectively FOLL_PIN, which is an mm/ internal flag).
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* The page *must* be pinned if KVM will write to the page via a kernel
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* mapping, e.g. via kmap(), mremap(), etc.
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*/
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bool pin;
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/*
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* If non-NULL, try to get a writable mapping even for a read fault.
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* Set to true if a writable mapping was obtained.
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*/
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bool *map_writable;
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/*
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* Optional output. Set to a valid "struct page" if the returned pfn
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* is for a refcounted or pinned struct page, NULL if the returned pfn
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* has no struct page or if the struct page is not being refcounted
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* (e.g. tail pages of non-compound higher order allocations from
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* IO/PFNMAP mappings).
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*/
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struct page **refcounted_page;
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};
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kvm_pfn_t hva_to_pfn(struct kvm_follow_pfn *kfp);
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#ifdef CONFIG_HAVE_KVM_PFNCACHE
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void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
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unsigned long start,
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unsigned long end);
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#else
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static inline void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm,
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unsigned long start,
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unsigned long end)
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{
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}
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#endif /* HAVE_KVM_PFNCACHE */
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#ifdef CONFIG_KVM_GUEST_MEMFD
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int kvm_gmem_init(struct module *module);
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void kvm_gmem_exit(void);
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int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args);
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int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
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unsigned int fd, loff_t offset);
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void kvm_gmem_unbind(struct kvm_memory_slot *slot);
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#else
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static inline int kvm_gmem_init(struct module *module)
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{
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return 0;
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}
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static inline void kvm_gmem_exit(void) {};
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static inline int kvm_gmem_bind(struct kvm *kvm,
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struct kvm_memory_slot *slot,
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unsigned int fd, loff_t offset)
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{
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WARN_ON_ONCE(1);
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return -EIO;
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}
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static inline void kvm_gmem_unbind(struct kvm_memory_slot *slot)
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{
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WARN_ON_ONCE(1);
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}
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#endif /* CONFIG_KVM_GUEST_MEMFD */
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#endif /* __KVM_MM_H__ */
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