Re: [Qemu-devel] [PATCH v2 1/7] s390x/pci: factor out endianess conversion

[Pierre Morel]

On 21/11/2017 11:35, Cornelia Huck wrote:
> On Thu, 16 Nov 2017 18:51:49 +0100
> Pierre Morel <address@hidden> wrote:
>
> > There are two places where the same endianness conversion
> > is done.
> > Let's factor this out into a static function.
> >
> > Signed-off-by: Pierre Morel <address@hidden>
> > Reviewed-by: Yi Min Zhao <address@hidden>
> > Signed-off-by: Pierre Morel <address@hidden>
>
> Your two s-o-bs look a bit odd...
>
> > ---
> >   hw/s390x/s390-pci-inst.c | 59 +++++++++++++++++++++++++++---------------------
> >   1 file changed, 33 insertions(+), 26 deletions(-)
> >
> > diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
> > index 8e088f3..ded1556 100644
> > --- a/hw/s390x/s390-pci-inst.c
> > +++ b/hw/s390x/s390-pci-inst.c
> > @@ -314,6 +314,36 @@ out:
> >       return 0;
> >   }
> >   
> > +/**
> > + * This function is called when endianess is fixed, whatever the host endianess
> > + * is, like in our case from s390x BIG endian registers to little endian PCI
> > + * Bars, to translate the uint64_t pointed from one endianess to the other.
>
> I would rephrase this a bit:
>
> "Swap data contained in s390x big endian registers to little endian PCI
> bars."

Simpler and clearer. thanks.

> That makes it clear that this function is for a specialized use case.
>
> > + *
> > + * @ptr: a pointer to a uint64_t data field
> > + * @len: the length of the valid data, must be 1,2,4 or 8
> > + */
> > +static int zpci_endian_swap(uint64_t *ptr, uint8_t len)
> > +{
> > +    uint64_t data = *ptr;
>
> Please add an extra empty line.

yes.

> > +    switch (len) {
> > +    case 1:
> > +        break;
> > +    case 2:
> > +        data = bswap16(data);
> > +        break;
> > +    case 4:
> > +        data = bswap32(data);
> > +        break;
> > +    case 8:
> > +        data = bswap64(data);
> > +        break;
> > +    default:
> > +        return -EINVAL;
> > +    }
> > +    *ptr = data;
> > +    return 0;
> > +}
> > +
> >   int pcilg_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2)
> >   {
> >       CPUS390XState *env = &cpu->env;
>
> Other than the nits above, looks good.

Thanks for the review

Pierre

--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany