Re: [Qemu-devel] [PATCH 2/2] intel_iommu: Fix unexpected unmaps during global unmap

[Peter Xu <peterx@redhat.com>]

On Mon, Jun 24, 2019 at 10:43:21AM +0200, Paolo Bonzini wrote:
> 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.

OK.

> 
> > +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;
> 

(I'll add another "alignment = MIN(alignment, max_mask)" here if no
 one disagree...)

>     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.

Will do.  Thanks,

-- 
Peter Xu