1 files changed, 52 insertions, 0 deletions
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
index bfe437098b79..5d6c87bb13f6 100644
--- a/virt/kvm/guest_memfd.c
+++ b/virt/kvm/guest_memfd.c
@@ -585,3 +585,55 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot,
 	return r;
 }
 EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn);
+
+long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long npages,
+		       kvm_gmem_populate_cb post_populate, void *opaque)
+{
+	struct file *file;
+	struct kvm_memory_slot *slot;
+	void __user *p;
+
+	int ret = 0, max_order;
+	long i;
+
+	lockdep_assert_held(&kvm->slots_lock);
+	if (npages < 0)
+		return -EINVAL;
+
+	slot = gfn_to_memslot(kvm, start_gfn);
+	if (!kvm_slot_can_be_private(slot))
+		return -EINVAL;
+
+	file = kvm_gmem_get_file(slot);
+	if (!file)
+		return -EFAULT;
+
+	filemap_invalidate_lock(file->f_mapping);
+
+	npages = min_t(ulong, slot->npages - (start_gfn - slot->base_gfn), npages);
+	for (i = 0; i < npages; i += (1 << max_order)) {
+		gfn_t gfn = start_gfn + i;
+		kvm_pfn_t pfn;
+
+		ret = __kvm_gmem_get_pfn(file, slot, gfn, &pfn, &max_order, false);
+		if (ret)
+			break;
+
+		if (!IS_ALIGNED(gfn, (1 << max_order)) ||
+		    (npages - i) < (1 << max_order))
+			max_order = 0;
+
+		p = src ? src + i * PAGE_SIZE : NULL;
+		ret = post_populate(kvm, gfn, pfn, p, max_order, opaque);
+
+		put_page(pfn_to_page(pfn));
+		if (ret)
+			break;
+	}
+
+	filemap_invalidate_unlock(file->f_mapping);
+
+	fput(file);
+	return ret && !i ? ret : i;
+}
+EXPORT_SYMBOL_GPL(kvm_gmem_populate);