Re: [Qemu-devel] [PATCH] virtio: fix vring_align() on 64-bit win32 platforms

[Eric Blake]

On 03/21/2017 05:31 PM, Andrew Baumann wrote:
> "long" is 32-bits on win32, but we need to promote it to a 64-bit hwaddr
> before negating, or else the top half of the address is truncated
> 
> Signed-off-by: Andrew Baumann <address@hidden>
> ---
>  include/hw/virtio/virtio.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 15efcf2..a0a8543 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -34,7 +34,7 @@ struct VirtQueue;
>  static inline hwaddr vring_align(hwaddr addr,
>                                               unsigned long align)
>  {
> -    return (addr + align - 1) & ~(align - 1);
> +    return (addr + align - 1) & ~(hwaddr)(align - 1);

Why not just use the QEMU_ALIGN_DOWN macro, instead of open-coding it?

(Hmm - a good BiteSized task might be to come up with a Coccinelle
script to help replace all open-coded rounding functions with
appropriate macro calls instead)

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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