Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm updates from Paolo Bonzini:
 "Generic:

   - Use memdup_array_user() to harden against overflow.

   - Unconditionally advertise KVM_CAP_DEVICE_CTRL for all
     architectures.

   - Clean up Kconfigs that all KVM architectures were selecting

   - New functionality around "guest_memfd", a new userspace API that
     creates an anonymous file and returns a file descriptor that refers
     to it. guest_memfd files are bound to their owning virtual machine,
     cannot be mapped, read, or written by userspace, and cannot be
     resized. guest_memfd files do however support PUNCH_HOLE, which can
     be used to switch a memory area between guest_memfd and regular
     anonymous memory.

   - New ioctl KVM_SET_MEMORY_ATTRIBUTES allowing userspace to specify
     per-page attributes for a given page of guest memory; right now the
     only attribute is whether the guest expects to access memory via
     guest_memfd or not, which in Confidential SVMs backed by SEV-SNP,
     TDX or ARM64 pKVM is checked by firmware or hypervisor that
     guarantees confidentiality (AMD PSP, Intel TDX module, or EL2 in
     the case of pKVM).

  x86:

   - Support for "software-protected VMs" that can use the new
     guest_memfd and page attributes infrastructure. This is mostly
     useful for testing, since there is no pKVM-like infrastructure to
     provide a meaningfully reduced TCB.

   - Fix a relatively benign off-by-one error when splitting huge pages
     during CLEAR_DIRTY_LOG.

   - Fix a bug where KVM could incorrectly test-and-clear dirty bits in
     non-leaf TDP MMU SPTEs if a racing thread replaces a huge SPTE with
     a non-huge SPTE.

   - Use more generic lockdep assertions in paths that don't actually
     care about whether the caller is a reader or a writer.

   - let Xen guests opt out of having PV clock reported as "based on a
     stable TSC", because some of them don't expect the "TSC stable" bit
     (added to the pvclock ABI by KVM, but never set by Xen) to be set.

   - Revert a bogus, made-up nested SVM consistency check for
     TLB_CONTROL.

   - Advertise flush-by-ASID support for nSVM unconditionally, as KVM
     always flushes on nested transitions, i.e. always satisfies flush
     requests. This allows running bleeding edge versions of VMware
     Workstation on top of KVM.

   - Sanity check that the CPU supports flush-by-ASID when enabling SEV
     support.

   - On AMD machines with vNMI, always rely on hardware instead of
     intercepting IRET in some cases to detect unmasking of NMIs

   - Support for virtualizing Linear Address Masking (LAM)

   - Fix a variety of vPMU bugs where KVM fail to stop/reset counters
     and other state prior to refreshing the vPMU model.

   - Fix a double-overflow PMU bug by tracking emulated counter events
     using a dedicated field instead of snapshotting the "previous"
     counter. If the hardware PMC count triggers overflow that is
     recognized in the same VM-Exit that KVM manually bumps an event
     count, KVM would pend PMIs for both the hardware-triggered overflow
     and for KVM-triggered overflow.

   - Turn off KVM_WERROR by default for all configs so that it's not
     inadvertantly enabled by non-KVM developers, which can be
     problematic for subsystems that require no regressions for W=1
     builds.

   - Advertise all of the host-supported CPUID bits that enumerate
     IA32_SPEC_CTRL "features".

   - Don't force a masterclock update when a vCPU synchronizes to the
     current TSC generation, as updating the masterclock can cause
     kvmclock's time to "jump" unexpectedly, e.g. when userspace
     hotplugs a pre-created vCPU.

   - Use RIP-relative address to read kvm_rebooting in the VM-Enter
     fault paths, partly as a super minor optimization, but mostly to
     make KVM play nice with position independent executable builds.

   - Guard KVM-on-HyperV's range-based TLB flush hooks with an #ifdef on
     CONFIG_HYPERV as a minor optimization, and to self-document the
     code.

   - Add CONFIG_KVM_HYPERV to allow disabling KVM support for HyperV
     "emulation" at build time.

  ARM64:

   - LPA2 support, adding 52bit IPA/PA capability for 4kB and 16kB base
     granule sizes. Branch shared with the arm64 tree.

   - Large Fine-Grained Trap rework, bringing some sanity to the
     feature, although there is more to come. This comes with a prefix
     branch shared with the arm64 tree.

   - Some additional Nested Virtualization groundwork, mostly
     introducing the NV2 VNCR support and retargetting the NV support to
     that version of the architecture.

   - A small set of vgic fixes and associated cleanups.

  Loongarch:

   - Optimization for memslot hugepage checking

   - Cleanup and fix some HW/SW timer issues

   - Add LSX/LASX (128bit/256bit SIMD) support

  RISC-V:

   - KVM_GET_REG_LIST improvement for vector registers

   - Generate ISA extension reg_list using macros in get-reg-list
     selftest

   - Support for reporting steal time along with selftest

  s390:

   - Bugfixes

  Selftests:

   - Fix an annoying goof where the NX hugepage test prints out garbage
     instead of the magic token needed to run the test.

   - Fix build errors when a header is delete/moved due to a missing
     flag in the Makefile.

   - Detect if KVM bugged/killed a selftest's VM and print out a helpful
     message instead of complaining that a random ioctl() failed.

   - Annotate the guest printf/assert helpers with __printf(), and fix
     the various bugs that were lurking due to lack of said annotation"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (185 commits)
  x86/kvm: Do not try to disable kvmclock if it was not enabled
  KVM: x86: add missing "depends on KVM"
  KVM: fix direction of dependency on MMU notifiers
  KVM: introduce CONFIG_KVM_COMMON
  KVM: arm64: Add missing memory barriers when switching to pKVM's hyp pgd
  KVM: arm64: vgic-its: Avoid potential UAF in LPI translation cache
  RISC-V: KVM: selftests: Add get-reg-list test for STA registers
  RISC-V: KVM: selftests: Add steal_time test support
  RISC-V: KVM: selftests: Add guest_sbi_probe_extension
  RISC-V: KVM: selftests: Move sbi_ecall to processor.c
  RISC-V: KVM: Implement SBI STA extension
  RISC-V: KVM: Add support for SBI STA registers
  RISC-V: KVM: Add support for SBI extension registers
  RISC-V: KVM: Add SBI STA info to vcpu_arch
  RISC-V: KVM: Add steal-update vcpu request
  RISC-V: KVM: Add SBI STA extension skeleton
  RISC-V: paravirt: Implement steal-time support
  RISC-V: Add SBI STA extension definitions
  RISC-V: paravirt: Add skeleton for pv-time support
  RISC-V: KVM: Fix indentation in kvm_riscv_vcpu_set_reg_csr()
  ...

diff --cc Documentation/admin-guide/kernel-parameters.txt
Simple merge

diff --cc arch/arm64/kernel/cpufeature.c
Simple merge

diff --cc arch/arm64/kvm/hyp/nvhe/pkvm.c
Simple merge

diff --cc arch/arm64/kvm/sys_regs.c
Simple merge

diff --cc arch/powerpc/kvm/book3s_hv.c
Simple merge

diff --cc arch/riscv/Kconfig
Simple merge

diff --cc arch/riscv/kernel/Makefile
Simple merge

diff --cc arch/s390/kvm/kvm-s390.c
Simple merge

diff --cc arch/x86/include/asm/kvm_host.h
Simple merge

diff --cc arch/x86/kernel/kvmclock.c
Simple merge

diff --cc arch/x86/kvm/cpuid.c
Simple merge

diff --cc arch/x86/kvm/mmu/mmu.c
Simple merge

diff --cc arch/x86/kvm/svm/svm.c
Simple merge

diff --cc arch/x86/kvm/vmx/nested.c
Simple merge

diff --cc arch/x86/kvm/vmx/vmx.c
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge

diff --cc arch/x86/kvm/xen.c
Simple merge

diff --cc fs/userfaultfd.c
Simple merge

diff --cc io_uring/io_uring.c
index 09b6d86,0efd775..86761ec
--- 1/io_uring/io_uring.c
--- 2/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@@ -3787,8 -3871,28 +3787,9 @@@ static int io_uring_install_fd(struct f
   */
  static struct file *io_uring_get_file(struct io_ring_ctx *ctx)
  {
-       return anon_inode_getfile_secure("[io_uring]", &io_uring_fops, ctx,
 -      struct file *file;
 -#if defined(CONFIG_UNIX)
 -      int ret;
 -
 -      ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
 -                              &ctx->ring_sock);
 -      if (ret)
 -              return ERR_PTR(ret);
 -#endif
 -
+       /* Create a new inode so that the LSM can block the creation.  */
 -      file = anon_inode_create_getfile("[io_uring]", &io_uring_fops, ctx,
++      return anon_inode_create_getfile("[io_uring]", &io_uring_fops, ctx,
                                         O_RDWR | O_CLOEXEC, NULL);
 -#if defined(CONFIG_UNIX)
 -      if (IS_ERR(file)) {
 -              sock_release(ctx->ring_sock);
 -              ctx->ring_sock = NULL;
 -      } else {
 -              ctx->ring_sock->file = file;
 -      }
 -#endif
 -      return file;
  }
  
  static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,

diff --cc mm/compaction.c
Simple merge

diff --cc mm/migrate.c
Simple merge

diff --cc virt/kvm/eventfd.c
Simple merge

diff --cc virt/kvm/guest_memfd.c
index 0000000,c2e2371..0f4e0cf
mode 000000,100644..100644
--- /dev/null
--- 2/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@@ -1,0 -1,532 +1,532 @@@
 -      struct list_head *gmem_list = &inode->i_mapping->private_list;
+ // SPDX-License-Identifier: GPL-2.0
+ #include <linux/backing-dev.h>
+ #include <linux/falloc.h>
+ #include <linux/kvm_host.h>
+ #include <linux/pagemap.h>
+ #include <linux/anon_inodes.h>
+ 
+ #include "kvm_mm.h"
+ 
+ struct kvm_gmem {
+       struct kvm *kvm;
+       struct xarray bindings;
+       struct list_head entry;
+ };
+ 
+ static struct folio *kvm_gmem_get_folio(struct inode *inode, pgoff_t index)
+ {
+       struct folio *folio;
+ 
+       /* TODO: Support huge pages. */
+       folio = filemap_grab_folio(inode->i_mapping, index);
+       if (IS_ERR_OR_NULL(folio))
+               return NULL;
+ 
+       /*
+        * Use the up-to-date flag to track whether or not the memory has been
+        * zeroed before being handed off to the guest.  There is no backing
+        * storage for the memory, so the folio will remain up-to-date until
+        * it's removed.
+        *
+        * TODO: Skip clearing pages when trusted firmware will do it when
+        * assigning memory to the guest.
+        */
+       if (!folio_test_uptodate(folio)) {
+               unsigned long nr_pages = folio_nr_pages(folio);
+               unsigned long i;
+ 
+               for (i = 0; i < nr_pages; i++)
+                       clear_highpage(folio_page(folio, i));
+ 
+               folio_mark_uptodate(folio);
+       }
+ 
+       /*
+        * Ignore accessed, referenced, and dirty flags.  The memory is
+        * unevictable and there is no storage to write back to.
+        */
+       return folio;
+ }
+ 
+ static void kvm_gmem_invalidate_begin(struct kvm_gmem *gmem, pgoff_t start,
+                                     pgoff_t end)
+ {
+       bool flush = false, found_memslot = false;
+       struct kvm_memory_slot *slot;
+       struct kvm *kvm = gmem->kvm;
+       unsigned long index;
+ 
+       xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) {
+               pgoff_t pgoff = slot->gmem.pgoff;
+ 
+               struct kvm_gfn_range gfn_range = {
+                       .start = slot->base_gfn + max(pgoff, start) - pgoff,
+                       .end = slot->base_gfn + min(pgoff + slot->npages, end) - pgoff,
+                       .slot = slot,
+                       .may_block = true,
+               };
+ 
+               if (!found_memslot) {
+                       found_memslot = true;
+ 
+                       KVM_MMU_LOCK(kvm);
+                       kvm_mmu_invalidate_begin(kvm);
+               }
+ 
+               flush |= kvm_mmu_unmap_gfn_range(kvm, &gfn_range);
+       }
+ 
+       if (flush)
+               kvm_flush_remote_tlbs(kvm);
+ 
+       if (found_memslot)
+               KVM_MMU_UNLOCK(kvm);
+ }
+ 
+ static void kvm_gmem_invalidate_end(struct kvm_gmem *gmem, pgoff_t start,
+                                   pgoff_t end)
+ {
+       struct kvm *kvm = gmem->kvm;
+ 
+       if (xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) {
+               KVM_MMU_LOCK(kvm);
+               kvm_mmu_invalidate_end(kvm);
+               KVM_MMU_UNLOCK(kvm);
+       }
+ }
+ 
+ static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
+ {
 -static int kvm_gmem_error_page(struct address_space *mapping, struct page *page)
++      struct list_head *gmem_list = &inode->i_mapping->i_private_list;
+       pgoff_t start = offset >> PAGE_SHIFT;
+       pgoff_t end = (offset + len) >> PAGE_SHIFT;
+       struct kvm_gmem *gmem;
+ 
+       /*
+        * Bindings must be stable across invalidation to ensure the start+end
+        * are balanced.
+        */
+       filemap_invalidate_lock(inode->i_mapping);
+ 
+       list_for_each_entry(gmem, gmem_list, entry)
+               kvm_gmem_invalidate_begin(gmem, start, end);
+ 
+       truncate_inode_pages_range(inode->i_mapping, offset, offset + len - 1);
+ 
+       list_for_each_entry(gmem, gmem_list, entry)
+               kvm_gmem_invalidate_end(gmem, start, end);
+ 
+       filemap_invalidate_unlock(inode->i_mapping);
+ 
+       return 0;
+ }
+ 
+ static long kvm_gmem_allocate(struct inode *inode, loff_t offset, loff_t len)
+ {
+       struct address_space *mapping = inode->i_mapping;
+       pgoff_t start, index, end;
+       int r;
+ 
+       /* Dedicated guest is immutable by default. */
+       if (offset + len > i_size_read(inode))
+               return -EINVAL;
+ 
+       filemap_invalidate_lock_shared(mapping);
+ 
+       start = offset >> PAGE_SHIFT;
+       end = (offset + len) >> PAGE_SHIFT;
+ 
+       r = 0;
+       for (index = start; index < end; ) {
+               struct folio *folio;
+ 
+               if (signal_pending(current)) {
+                       r = -EINTR;
+                       break;
+               }
+ 
+               folio = kvm_gmem_get_folio(inode, index);
+               if (!folio) {
+                       r = -ENOMEM;
+                       break;
+               }
+ 
+               index = folio_next_index(folio);
+ 
+               folio_unlock(folio);
+               folio_put(folio);
+ 
+               /* 64-bit only, wrapping the index should be impossible. */
+               if (WARN_ON_ONCE(!index))
+                       break;
+ 
+               cond_resched();
+       }
+ 
+       filemap_invalidate_unlock_shared(mapping);
+ 
+       return r;
+ }
+ 
+ static long kvm_gmem_fallocate(struct file *file, int mode, loff_t offset,
+                              loff_t len)
+ {
+       int ret;
+ 
+       if (!(mode & FALLOC_FL_KEEP_SIZE))
+               return -EOPNOTSUPP;
+ 
+       if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+               return -EOPNOTSUPP;
+ 
+       if (!PAGE_ALIGNED(offset) || !PAGE_ALIGNED(len))
+               return -EINVAL;
+ 
+       if (mode & FALLOC_FL_PUNCH_HOLE)
+               ret = kvm_gmem_punch_hole(file_inode(file), offset, len);
+       else
+               ret = kvm_gmem_allocate(file_inode(file), offset, len);
+ 
+       if (!ret)
+               file_modified(file);
+       return ret;
+ }
+ 
+ static int kvm_gmem_release(struct inode *inode, struct file *file)
+ {
+       struct kvm_gmem *gmem = file->private_data;
+       struct kvm_memory_slot *slot;
+       struct kvm *kvm = gmem->kvm;
+       unsigned long index;
+ 
+       /*
+        * Prevent concurrent attempts to *unbind* a memslot.  This is the last
+        * reference to the file and thus no new bindings can be created, but
+        * dereferencing the slot for existing bindings needs to be protected
+        * against memslot updates, specifically so that unbind doesn't race
+        * and free the memslot (kvm_gmem_get_file() will return NULL).
+        */
+       mutex_lock(&kvm->slots_lock);
+ 
+       filemap_invalidate_lock(inode->i_mapping);
+ 
+       xa_for_each(&gmem->bindings, index, slot)
+               rcu_assign_pointer(slot->gmem.file, NULL);
+ 
+       synchronize_rcu();
+ 
+       /*
+        * All in-flight operations are gone and new bindings can be created.
+        * Zap all SPTEs pointed at by this file.  Do not free the backing
+        * memory, as its lifetime is associated with the inode, not the file.
+        */
+       kvm_gmem_invalidate_begin(gmem, 0, -1ul);
+       kvm_gmem_invalidate_end(gmem, 0, -1ul);
+ 
+       list_del(&gmem->entry);
+ 
+       filemap_invalidate_unlock(inode->i_mapping);
+ 
+       mutex_unlock(&kvm->slots_lock);
+ 
+       xa_destroy(&gmem->bindings);
+       kfree(gmem);
+ 
+       kvm_put_kvm(kvm);
+ 
+       return 0;
+ }
+ 
+ static inline struct file *kvm_gmem_get_file(struct kvm_memory_slot *slot)
+ {
+       /*
+        * Do not return slot->gmem.file if it has already been closed;
+        * there might be some time between the last fput() and when
+        * kvm_gmem_release() clears slot->gmem.file, and you do not
+        * want to spin in the meanwhile.
+        */
+       return get_file_active(&slot->gmem.file);
+ }
+ 
+ static struct file_operations kvm_gmem_fops = {
+       .open           = generic_file_open,
+       .release        = kvm_gmem_release,
+       .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)
+ {
+       WARN_ON_ONCE(1);
+       return -EINVAL;
+ }
+ 
 -      struct list_head *gmem_list = &mapping->private_list;
++static int kvm_gmem_error_folio(struct address_space *mapping, struct folio *folio)
+ {
 -      start = page->index;
 -      end = start + thp_nr_pages(page);
++      struct list_head *gmem_list = &mapping->i_private_list;
+       struct kvm_gmem *gmem;
+       pgoff_t start, end;
+ 
+       filemap_invalidate_lock_shared(mapping);
+ 
 -      .error_remove_page = kvm_gmem_error_page,
++      start = folio->index;
++      end = start + folio_nr_pages(folio);
+ 
+       list_for_each_entry(gmem, gmem_list, entry)
+               kvm_gmem_invalidate_begin(gmem, start, end);
+ 
+       /*
+        * Do not truncate the range, what action is taken in response to the
+        * error is userspace's decision (assuming the architecture supports
+        * gracefully handling memory errors).  If/when the guest attempts to
+        * access a poisoned page, kvm_gmem_get_pfn() will return -EHWPOISON,
+        * at which point KVM can either terminate the VM or propagate the
+        * error to userspace.
+        */
+ 
+       list_for_each_entry(gmem, gmem_list, entry)
+               kvm_gmem_invalidate_end(gmem, start, end);
+ 
+       filemap_invalidate_unlock_shared(mapping);
+ 
+       return MF_DELAYED;
+ }
+ 
+ static const struct address_space_operations kvm_gmem_aops = {
+       .dirty_folio = noop_dirty_folio,
+       .migrate_folio  = kvm_gmem_migrate_folio,
 -      list_add(&gmem->entry, &inode->i_mapping->private_list);
++      .error_remove_folio = kvm_gmem_error_folio,
+ };
+ 
+ static int kvm_gmem_getattr(struct mnt_idmap *idmap, const struct path *path,
+                           struct kstat *stat, u32 request_mask,
+                           unsigned int query_flags)
+ {
+       struct inode *inode = path->dentry->d_inode;
+ 
+       generic_fillattr(idmap, request_mask, inode, stat);
+       return 0;
+ }
+ 
+ static int kvm_gmem_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
+                           struct iattr *attr)
+ {
+       return -EINVAL;
+ }
+ static const struct inode_operations kvm_gmem_iops = {
+       .getattr        = kvm_gmem_getattr,
+       .setattr        = kvm_gmem_setattr,
+ };
+ 
+ static int __kvm_gmem_create(struct kvm *kvm, loff_t size, u64 flags)
+ {
+       const char *anon_name = "[kvm-gmem]";
+       struct kvm_gmem *gmem;
+       struct inode *inode;
+       struct file *file;
+       int fd, err;
+ 
+       fd = get_unused_fd_flags(0);
+       if (fd < 0)
+               return fd;
+ 
+       gmem = kzalloc(sizeof(*gmem), GFP_KERNEL);
+       if (!gmem) {
+               err = -ENOMEM;
+               goto err_fd;
+       }
+ 
+       file = anon_inode_create_getfile(anon_name, &kvm_gmem_fops, gmem,
+                                        O_RDWR, NULL);
+       if (IS_ERR(file)) {
+               err = PTR_ERR(file);
+               goto err_gmem;
+       }
+ 
+       file->f_flags |= O_LARGEFILE;
+ 
+       inode = file->f_inode;
+       WARN_ON(file->f_mapping != inode->i_mapping);
+ 
+       inode->i_private = (void *)(unsigned long)flags;
+       inode->i_op = &kvm_gmem_iops;
+       inode->i_mapping->a_ops = &kvm_gmem_aops;
+       inode->i_mode |= S_IFREG;
+       inode->i_size = size;
+       mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
+       mapping_set_unmovable(inode->i_mapping);
+       /* Unmovable mappings are supposed to be marked unevictable as well. */
+       WARN_ON_ONCE(!mapping_unevictable(inode->i_mapping));
+ 
+       kvm_get_kvm(kvm);
+       gmem->kvm = kvm;
+       xa_init(&gmem->bindings);
++      list_add(&gmem->entry, &inode->i_mapping->i_private_list);
+ 
+       fd_install(fd, file);
+       return fd;
+ 
+ err_gmem:
+       kfree(gmem);
+ err_fd:
+       put_unused_fd(fd);
+       return err;
+ }
+ 
+ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args)
+ {
+       loff_t size = args->size;
+       u64 flags = args->flags;
+       u64 valid_flags = 0;
+ 
+       if (flags & ~valid_flags)
+               return -EINVAL;
+ 
+       if (size <= 0 || !PAGE_ALIGNED(size))
+               return -EINVAL;
+ 
+       return __kvm_gmem_create(kvm, size, flags);
+ }
+ 
+ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot,
+                 unsigned int fd, loff_t offset)
+ {
+       loff_t size = slot->npages << PAGE_SHIFT;
+       unsigned long start, end;
+       struct kvm_gmem *gmem;
+       struct inode *inode;
+       struct file *file;
+       int r = -EINVAL;
+ 
+       BUILD_BUG_ON(sizeof(gfn_t) != sizeof(slot->gmem.pgoff));
+ 
+       file = fget(fd);
+       if (!file)
+               return -EBADF;
+ 
+       if (file->f_op != &kvm_gmem_fops)
+               goto err;
+ 
+       gmem = file->private_data;
+       if (gmem->kvm != kvm)
+               goto err;
+ 
+       inode = file_inode(file);
+ 
+       if (offset < 0 || !PAGE_ALIGNED(offset) ||
+           offset + size > i_size_read(inode))
+               goto err;
+ 
+       filemap_invalidate_lock(inode->i_mapping);
+ 
+       start = offset >> PAGE_SHIFT;
+       end = start + slot->npages;
+ 
+       if (!xa_empty(&gmem->bindings) &&
+           xa_find(&gmem->bindings, &start, end - 1, XA_PRESENT)) {
+               filemap_invalidate_unlock(inode->i_mapping);
+               goto err;
+       }
+ 
+       /*
+        * No synchronize_rcu() needed, any in-flight readers are guaranteed to
+        * be see either a NULL file or this new file, no need for them to go
+        * away.
+        */
+       rcu_assign_pointer(slot->gmem.file, file);
+       slot->gmem.pgoff = start;
+ 
+       xa_store_range(&gmem->bindings, start, end - 1, slot, GFP_KERNEL);
+       filemap_invalidate_unlock(inode->i_mapping);
+ 
+       /*
+        * Drop the reference to the file, even on success.  The file pins KVM,
+        * not the other way 'round.  Active bindings are invalidated if the
+        * file is closed before memslots are destroyed.
+        */
+       r = 0;
+ err:
+       fput(file);
+       return r;
+ }
+ 
+ void kvm_gmem_unbind(struct kvm_memory_slot *slot)
+ {
+       unsigned long start = slot->gmem.pgoff;
+       unsigned long end = start + slot->npages;
+       struct kvm_gmem *gmem;
+       struct file *file;
+ 
+       /*
+        * Nothing to do if the underlying file was already closed (or is being
+        * closed right now), kvm_gmem_release() invalidates all bindings.
+        */
+       file = kvm_gmem_get_file(slot);
+       if (!file)
+               return;
+ 
+       gmem = file->private_data;
+ 
+       filemap_invalidate_lock(file->f_mapping);
+       xa_store_range(&gmem->bindings, start, end - 1, NULL, GFP_KERNEL);
+       rcu_assign_pointer(slot->gmem.file, NULL);
+       synchronize_rcu();
+       filemap_invalidate_unlock(file->f_mapping);
+ 
+       fput(file);
+ }
+ 
+ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
+                    gfn_t gfn, kvm_pfn_t *pfn, int *max_order)
+ {
+       pgoff_t index = gfn - slot->base_gfn + slot->gmem.pgoff;
+       struct kvm_gmem *gmem;
+       struct folio *folio;
+       struct page *page;
+       struct file *file;
+       int r;
+ 
+       file = kvm_gmem_get_file(slot);
+       if (!file)
+               return -EFAULT;
+ 
+       gmem = file->private_data;
+ 
+       if (WARN_ON_ONCE(xa_load(&gmem->bindings, index) != slot)) {
+               r = -EIO;
+               goto out_fput;
+       }
+ 
+       folio = kvm_gmem_get_folio(file_inode(file), index);
+       if (!folio) {
+               r = -ENOMEM;
+               goto out_fput;
+       }
+ 
+       if (folio_test_hwpoison(folio)) {
+               r = -EHWPOISON;
+               goto out_unlock;
+       }
+ 
+       page = folio_file_page(folio, index);
+ 
+       *pfn = page_to_pfn(page);
+       if (max_order)
+               *max_order = 0;
+ 
+       r = 0;
+ 
+ out_unlock:
+       folio_unlock(folio);
+ out_fput:
+       fput(file);
+ 
+       return r;
+ }
+ EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn);