On 24/06/19 10:06, Peter Xu wrote:
> Well, if with such an error we'd better fix it right away in this
> patch... :)
>
> Let me wait for some more comments, I'll touch that up too if I need a
> repost.
Looks good to me, except for one minor issue in this patch. But do not
attribute this one to me, it's basically all code from you.
> +static uint64_t vtd_get_next_mask(uint64_t start, uint64_t size, int gaw)
> +{
> + /* Tries to find smallest mask from start first */
> + uint64_t rmask = start & -start, max_mask = 1ULL << gaw;
> +
> + assert(size && gaw > 0 && gaw < 64);
> +
> + /* Zero start, or too big */
> + if (!rmask || rmask > max_mask) {
> + rmask = max_mask;
> + }
Perhaps simpler:
uint64_t max_mask = 1ULL << gaw;
uint64_t alignment = start ? start & -start : max_mask;
size = MIN(size, max_mask);
if (alignment <= size) {
/* Increase the alignment of start */
return alignment;
} else {
/* Find the largest page mask from size */
return 1ULL << (63 - clz64(size));
}
Also please rename it to get_naturally_aligned_size.
Paolo
