Re: [Qemu-devel] [PATCH] virtio-serial: Fix endianness bug in the config space

[Amit Shah <amit.shah@redhat.com>]

On (Tue) 19 Apr 2011 [12:03:46], David Gibson wrote:
> From: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> The virtio serial specification requres that the values in the config
> space are encoded in native endian of the guest.
> 
> The qemu virtio-serial code did not do conversion to the guest endian
> format what caused problems when host and guest use different format.
> 
> This patch corrects the qemu side, correctly doing host-native <->
> guest-native conversions when accessing the config space. This won't
> break any setups that aren't already broken, and fixes the case
> of different host and guest endianness.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Thanks; please put your sign-off as well.

I'd also like an ACK from someone else before I push this in.  Juan?

> ---
>  hw/virtio-serial-bus.c |   23 +++++++++++++----------
>  1 files changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
> index 6227379..f10d48f 100644
> --- a/hw/virtio-serial-bus.c
> +++ b/hw/virtio-serial-bus.c
> @@ -494,7 +494,7 @@ static void virtio_serial_save(QEMUFile *f, void *opaque)
>      VirtIOSerial *s = opaque;
>      VirtIOSerialPort *port;
>      uint32_t nr_active_ports;
> -    unsigned int i;
> +    unsigned int i, max_nr_ports;
>  
>      /* The virtio device */
>      virtio_save(&s->vdev, f);
> @@ -506,8 +506,8 @@ static void virtio_serial_save(QEMUFile *f, void *opaque)
>      qemu_put_be32s(f, &s->config.max_nr_ports);
>  
>      /* The ports map */
> -
> -    for (i = 0; i < (s->config.max_nr_ports + 31) / 32; i++) {
> +    max_nr_ports = tswap32(s->config.max_nr_ports);
> +    for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
>          qemu_put_be32s(f, &s->ports_map[i]);
>      }
>  
> @@ -568,7 +568,8 @@ static int virtio_serial_load(QEMUFile *f, void *opaque, int version_id)
>      qemu_get_be16s(f, &s->config.rows);
>  
>      qemu_get_be32s(f, &max_nr_ports);
> -    if (max_nr_ports > s->config.max_nr_ports) {
> +    tswap32s(&max_nr_ports);
> +    if (max_nr_ports > tswap32(s->config.max_nr_ports)) {
>          /* Source could have had more ports than us. Fail migration. */
>          return -EINVAL;
>      }
> @@ -670,9 +671,10 @@ static void virtser_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent)
>  /* This function is only used if a port id is not provided by the user */
>  static uint32_t find_free_port_id(VirtIOSerial *vser)
>  {
> -    unsigned int i;
> +    unsigned int i, max_nr_ports;
>  
> -    for (i = 0; i < (vser->config.max_nr_ports + 31) / 32; i++) {
> +    max_nr_ports = tswap32(vser->config.max_nr_ports);
> +    for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
>          uint32_t map, bit;
>  
>          map = vser->ports_map[i];
> @@ -720,7 +722,7 @@ static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
>      VirtIOSerialPort *port = DO_UPCAST(VirtIOSerialPort, dev, qdev);
>      VirtIOSerialPortInfo *info = DO_UPCAST(VirtIOSerialPortInfo, qdev, base);
>      VirtIOSerialBus *bus = DO_UPCAST(VirtIOSerialBus, qbus, qdev->parent_bus);
> -    int ret;
> +    int ret, max_nr_ports;
>      bool plugging_port0;
>  
>      port->vser = bus->vser;
> @@ -750,9 +752,10 @@ static int virtser_port_qdev_init(DeviceState *qdev, DeviceInfo *base)
>          }
>      }
>  
> -    if (port->id >= port->vser->config.max_nr_ports) {
> +    max_nr_ports = tswap32(port->vser->config.max_nr_ports);
> +    if (port->id >= max_nr_ports) {
>          error_report("virtio-serial-bus: Out-of-range port id specified, max. allowed: %u\n",
> -                     port->vser->config.max_nr_ports - 1);
> +                     max_nr_ports - 1);
>          return -1;
>      }
>  
> @@ -863,7 +866,7 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, virtio_serial_conf *conf)
>          vser->ovqs[i] = virtio_add_queue(vdev, 128, handle_output);
>      }
>  
> -    vser->config.max_nr_ports = conf->max_virtserial_ports;
> +    vser->config.max_nr_ports = tswap32(conf->max_virtserial_ports);
>      vser->ports_map = qemu_mallocz(((conf->max_virtserial_ports + 31) / 32)
>          * sizeof(vser->ports_map[0]));
>      /*
> -- 
> 1.7.1
> 

		Amit