[SLOF] [PATCH v2 12/19] virtio: add 64-bit virtio helpers for 1.0

[Thomas Huth]

On 20.01.2016 13:10, Nikunj A Dadhania wrote:
> 64-bit fields are to be treated as two 32-bit fields, with low 32 bit
> part followed by the high 32 bit part.
> 
> Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>
> ---
>  lib/libvirtio/virtio.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/lib/libvirtio/virtio.c b/lib/libvirtio/virtio.c
> index 3f6859b..1331efd 100644
> --- a/lib/libvirtio/virtio.c
> +++ b/lib/libvirtio/virtio.c
> @@ -51,6 +51,31 @@ struct virtio_dev_common {
>  	le64 q_used;
>  } __attribute__ ((packed));
>  
> +/* virtio 1.0 Spec: 4.1.3 PCI Device Layout
> + *
> + * Fields of different sizes are present in the device configuration regions.
> + * All 64-bit, 32-bit and 16-bit fields are little-endian. 64-bit fields are to
> + * be treated as two 32-bit fields, with low 32 bit part followed by the high 32
> + * bit part.
> + */
> +static void virtio_write64(void *addr, uint64_t val)
> +{
> +	uint32_t hi = (val >> 32) & 0xFFFFFFFF;
> +	uint32_t lo = val & 0xFFFFFFFF;
> +
> +	ci_write_32(addr, cpu_to_le32(lo));
> +	ci_write_32(addr + 4, cpu_to_le32(hi));
> +}
> +
> +static uint64_t virtio_read64(void *addr)
> +{
> +	uint64_t hi, lo;
> +
> +	lo = le32_to_cpu(ci_read_32(addr));
> +	hi = le32_to_cpu(ci_read_32(addr + 4));
> +	return (hi << 32) | lo;
> +}

I'd maybe name them "virtio_pci_write64" and "virtio_pci_read64" to make
it clear that they are only to be used when reading and writing to the
PCI space - otherwise somebody might use them for accessing the virtio
rings one day, for example.

 Thomas