Re: [Qemu-devel] [PATCH v3 1/7] s390x/pci: factor out endianess conversion

[Cornelia Huck]

On Thu, 23 Nov 2017 09:48:41 +0100
Thomas Huth <address@hidden> wrote:

> On 22.11.2017 23:05, Pierre Morel 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>
> > ---
> >  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..3e1f1a0 100644
> > --- a/hw/s390x/s390-pci-inst.c
> > +++ b/hw/s390x/s390-pci-inst.c
> > @@ -314,6 +314,36 @@ out:
> >      return 0;
> >  }
> >  
> > +/**
> > + * Swap data contained in s390x big endian registers to little endian
> > + * PCI bars.
> > + *
> > + * @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;
> > +
> > +    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;
> > +}  
> 
> While you're at it, I think that should rather be leXX_to_cpu() instead
> of bswapXX() here,

I don't think that's correct, as this is supposed to swap BE registers
to LE PCI bars.

> though I'm not 100% sure, and we still can also fix
> that later, so:
> 
> Reviewed-by: Thomas Huth <address@hidden>