Re: [PATCH v8 10/46] KVM: guest_memfd: Wire up core private/shared attribute interfaces

[Binbin Wu]

On 6/19/2026 8:31 AM, Ackerley Tng via B4 Relay wrote:

[...]

> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index bca912db5be6e..e0e544ef47d69 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -926,6 +926,24 @@ 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_gmem_range_is_private(struct file *file, pgoff_t index,
> +				      size_t nr_pages, struct kvm *kvm, gfn_t gfn)
> +{
> +	struct maple_tree *mt = &GMEM_I(file_inode(file))->attributes;
> +	pgoff_t end = index + nr_pages - 1;
> +	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_for_each(mt, entry, index, end) {
> +		if (xa_to_value(entry) != KVM_MEMORY_ATTRIBUTE_PRIVATE)
> +			return false;
> +	}

Patch 1 noted that "Ensuring every index is represented in the maple tree at all times".
So I think the queried range should not be a hole in the maple tree.
However, there is a inconsistency: in patch 1 kvm_gmem_get_attributes() explicitly
checks for holes, but this patch does not.

> +	return true;
> +}
>