Re: [PATCHv3 08/17] x86/mm: Implement vma_is_encrypted() and vma_keyid()

[Dave Hansen]

On 06/12/2018 07:39 AM, Kirill A. Shutemov wrote:
> +bool vma_is_encrypted(struct vm_area_struct *vma)
> +{
> +	return pgprot_val(vma->vm_page_prot) & mktme_keyid_mask;
> +}
> +
> +int vma_keyid(struct vm_area_struct *vma)
> +{
> +	pgprotval_t prot;
> +
> +	if (!vma_is_anonymous(vma))
> +		return 0;
> +
> +	prot = pgprot_val(vma->vm_page_prot);
> +	return (prot & mktme_keyid_mask) >> mktme_keyid_shift;
> +}

Why do we have a vma_is_anonymous() in one of these but not the other?

While this reuse of ->vm_page_prot is cute, is there any downside?  It's
the first place I know of that we can't derive ->vm_page_prot from
->vm_flags on non-VM_IO/PFNMAP VMAs.  Is that a problem?