Re: [PATCH 3/5] ftgmac100: check RX and TX buffer alignment

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 1/7/20 8:34 AM, Cédric Le Goater wrote:
> These buffers should be aligned on 16 bytes.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> ---
>   hw/net/ftgmac100.c | 13 +++++++++++++
>   1 file changed, 13 insertions(+)
> 
> diff --git a/hw/net/ftgmac100.c b/hw/net/ftgmac100.c
> index 86ac25894a89..051f7b7af2d6 100644
> --- a/hw/net/ftgmac100.c
> +++ b/hw/net/ftgmac100.c
> @@ -198,6 +198,8 @@ typedef struct {
>       uint32_t        des3;
>   } FTGMAC100Desc;
>   
> +#define FTGMAC100_DESC_ALIGNMENT 16
> +
>   /*
>    * Specific RTL8211E MII Registers
>    */
> @@ -722,6 +724,12 @@ static void ftgmac100_write(void *opaque, hwaddr addr,
>           s->itc = value;
>           break;
>       case FTGMAC100_RXR_BADR: /* Ring buffer address */
> +        if (!QEMU_IS_ALIGNED(value, FTGMAC100_DESC_ALIGNMENT)) {
> +            qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad RX buffer alignment 0x%"
> +                          HWADDR_PRIx "\n", __func__, value);
> +            return;

What is the hardware behavior?

> +        }
> +
>           s->rx_ring = value;
>           s->rx_descriptor = s->rx_ring;
>           break;
> @@ -731,6 +739,11 @@ static void ftgmac100_write(void *opaque, hwaddr addr,
>           break;
>   
>       case FTGMAC100_NPTXR_BADR: /* Transmit buffer address */
> +        if (!QEMU_IS_ALIGNED(value, FTGMAC100_DESC_ALIGNMENT)) {
> +            qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad TX buffer alignment 0x%"
> +                          HWADDR_PRIx "\n", __func__, value);
> +            return;
> +        }
>           s->tx_ring = value;
>           s->tx_descriptor = s->tx_ring;
>           break;
>