[Qemu-devel] BUG report Re: [PATCH] spapr-pci: change endianness for io ports space

[Alexey Kardashevskiy <aik@ozlabs.ru>]

Hi!

Got a small lesson from Ben how to post stuff to the list and here are more
details :)

Every PCI device which uses IO ports (at least vga, e1000, virtio-pci,
rtl8139) is broken in the master branch of QEMU for powerpc-kvm. The
problem is exactly with endianness. For example, setup_vq() from
drivers/virtio/virtio_pci.c (guest kernel) fails on:

iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);

as QEMU receives msix_vec==0x100 instead of 0x1 in virtio_ioport_write().

The patch which broke it is b40acf99bef69fa8ab0f9092ff162fde945eec12
"ioport: Switch dispatching to memory core layer".

The patch below fixes this but I am not really sure it is correct. Is it?
Thanks.


On 07/12/2013 05:37 PM, Alexey Kardashevskiy wrote:
> sPAPR PHB emulates IO ports on PCI via a special memory region which
> routes all reads/writes further via cpu_in*/cpu_out* which are eventually
> processed by MemoryRegionOps implemented by devices.
> 
> As devices normally take care of endianness themselves by setting
> correct MemoryRegionOps::endianness for their memory regions, it is
> better to set endianness in spapr_io_ops to NATIVE.
> 
> Tested on sPAPR KVM with e1000, rtl8139, virtio-net.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
> 
> I would really appreciate if someone told me what exactly changed
> in QEMU and broke spapr-pci. It used to work... Thanks!
> 
> ---
>  hw/ppc/spapr_pci.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index ca588aa..dfe4d04 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -472,7 +472,7 @@ static void spapr_io_write(void *opaque, hwaddr addr,
>  }
>  
>  static const MemoryRegionOps spapr_io_ops = {
> -    .endianness = DEVICE_LITTLE_ENDIAN,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
>      .read = spapr_io_read,
>      .write = spapr_io_write
>  };
> 


-- 
Alexey