Re: [RFC PATCH] arm/kvm: Enable support for KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE

[Peter Maydell]

On Thu, 27 Jul 2023 at 16:43, Peter Maydell <peter.maydell@linaro.org> wrote:
>
> On Tue, 25 Jul 2023 at 16:01, Shameer Kolothum
> <shameerali.kolothum.thodi@huawei.com> wrote:
> > +static bool kvm_arm_eager_split_size_valid(uint64_t req_size, uint32_t 
> > sizes)
> > +{
> > +    int i;
> > +
> > +    for (i = 0; i < sizeof(uint32_t) * BITS_PER_BYTE; i++) {
> > +        if (!(sizes & (1 << i))) {
> > +            continue;
> > +        }
> > +
> > +        if (req_size == (1 << i)) {
> > +            return true;
> > +        }
> > +    }
>
> We know req_size is a power of 2 here, so if you also explicitly
> rule out 0 then you can do
>      return sizes & (1 << ctz64(req_size));

Er, that's also over-complicated. Just
   return sizes & req_size;

should do (and catches the 0 case correctly again).

-- PMM