Re: [PATCH v9 07/41] KVM: guest_memfd: Wire up core private/shared attribute interfaces

[Xiaoyao Li]

On 7/29/2026 8:35 AM, Ackerley Tng via B4 Relay wrote:

diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index 33c9830190e2e..89cf922232920 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -893,6 +893,27 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct 
kvm_memory_slot *slot,
  EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_get_pfn);

#ifdef CONFIG_HAVE_KVM_ARCH_GMEM_POPULATE

+static bool kvm_range_is_private(struct file *file, pgoff_t index,
+                                size_t nr_pages, struct kvm *kvm, gfn_t gfn)
+{
+       struct inode *inode = file_inode(file);
+       pgoff_t last = index + nr_pages - 1;
+       struct maple_tree *mt;
+       void *entry;
+
+       if (!gmem_in_place_conversion)
+               return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + 
nr_pages,
+                                                         
KVM_MEMORY_ATTRIBUTE_PRIVATE,
+                                                         
KVM_MEMORY_ATTRIBUTE_PRIVATE);
+
+       mt = &GMEM_I(inode)->attributes;
+       mt_for_each(mt, entry, index, last) {
+               if (kvm_gmem_interpret_entry(inode, entry) !=
+                   KVM_MEMORY_ATTRIBUTE_PRIVATE)
+                       return false;
+       }
+       return true;
+}

static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot,

                                struct file *file, gfn_t gfn, struct page 
*src_page,
@@ -913,9 +934,7 @@ static long __kvm_gmem_populate(struct kvm *kvm, struct 
kvm_memory_slot *slot,

folio_unlock(folio); - if (!kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + 1,

-                                               KVM_MEMORY_ATTRIBUTE_PRIVATE,
-                                               KVM_MEMORY_ATTRIBUTE_PRIVATE)) {
+       if (!kvm_range_is_private(file, index, 1, kvm, gfn)) {

It's checking if a single gfn is private.

We can just use kvm_mem_is_private()? And it seems can be a separate patch.

                ret = -EINVAL;
                goto out_put_folio;
        }