[PATCHv2,for-1.4] e1000: unbreak the guest network migration to 1.3

QEMU 1.3 does not emulate the link auto negotiation, so if migrate to a
1.3 machine during link auto negotiation, the guest link will be set to down.
Fix this by just disabling auto negotiation for 1.3 and older.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/e1000.c   | 25 +++++++++++++++++++++++++
 hw/pc_piix.c |  4 ++++
 2 files changed, 29 insertions(+)

On 02/27/2013 05:53 AM, Michael S. Tsirkin wrote:
> QEMU 1.3 does not emulate the link auto negotiation, so if migrate to a
> 1.3 machine during link auto negotiation, the guest link will be set to down.
> Fix this by just disabling auto negotiation for 1.3 and older.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Reviewed-by: Jason Wang <jasowang@redhat.com>

Thanks.
> ---
>  hw/e1000.c   | 25 +++++++++++++++++++++++++
>  hw/pc_piix.c |  4 ++++
>  2 files changed, 29 insertions(+)
>
> diff --git a/hw/e1000.c b/hw/e1000.c
> index d6fe815..876d421 100644
> --- a/hw/e1000.c
> +++ b/hw/e1000.c
> @@ -131,6 +131,11 @@ typedef struct E1000State_st {
>      } eecd_state;
>  
>      QEMUTimer *autoneg_timer;
> +
> +/* Compatibility flags for migration to/from qemu 1.3.0 and older */
> +#define E1000_FLAG_AUTONEG_BIT 0
> +#define E1000_FLAG_AUTONEG (1 << E1000_FLAG_AUTONEG_BIT)
> +    uint32_t compat_flags;
>  } E1000State;
>  
>  #define	defreg(x)	x = (E1000_##x>>2)
> @@ -165,6 +170,14 @@ e1000_link_up(E1000State *s)
>  static void
>  set_phy_ctrl(E1000State *s, int index, uint16_t val)
>  {
> +    /*
> +     * QEMU 1.3 does not support link auto-negotiation emulation, so if we
> +     * migrate during auto negotiation, after migration the link will be
> +     * down.
> +     */
> +    if (!(s->compat_flags & E1000_FLAG_AUTONEG)) {
> +        return;
> +    }
>      if ((val & MII_CR_AUTO_NEG_EN) && (val & MII_CR_RESTART_AUTO_NEG)) {
>          e1000_link_down(s);
>          s->phy_reg[PHY_STATUS] &= ~MII_SR_AUTONEG_COMPLETE;
> @@ -1120,6 +1133,11 @@ static void e1000_pre_save(void *opaque)
>  {
>      E1000State *s = opaque;
>      NetClientState *nc = qemu_get_queue(s->nic);
> +
> +    if (!(s->compat_flags & E1000_FLAG_AUTONEG)) {
> +        return;
> +    }
> +
>      /*
>       * If link is down and auto-negotiation is ongoing, complete
>       * auto-negotiation immediately.  This allows is to look at
> @@ -1141,6 +1159,11 @@ static int e1000_post_load(void *opaque, int version_id)
>       * to link status bit in mac_reg[STATUS].
>       * Alternatively, restart link negotiation if it was in progress. */
>      nc->link_down = (s->mac_reg[STATUS] & E1000_STATUS_LU) == 0;
> +
> +    if (!(s->compat_flags & E1000_FLAG_AUTONEG)) {
> +        return 0;
> +    }
> +
>      if (s->phy_reg[PHY_CTRL] & MII_CR_AUTO_NEG_EN &&
>          s->phy_reg[PHY_CTRL] & MII_CR_RESTART_AUTO_NEG &&
>          !(s->phy_reg[PHY_STATUS] & MII_SR_AUTONEG_COMPLETE)) {
> @@ -1343,6 +1366,8 @@ static void qdev_e1000_reset(DeviceState *dev)
>  
>  static Property e1000_properties[] = {
>      DEFINE_NIC_PROPERTIES(E1000State, conf),
> +    DEFINE_PROP_BIT("autonegotiation", E1000State,
> +                    compat_flags, E1000_FLAG_AUTONEG_BIT, true),
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 0af436c..6de2476 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -520,6 +520,10 @@ static QEMUMachine pc_machine_v0_14 = {
>              .driver   = "AC97",\
>              .property = "use_broken_id",\
>              .value    = stringify(1),\
> +        },{\
> +            .driver   = "e1000",\
> +            .property = "autonegotiation",\
> +            .value    = "off",\
>          }
>  
>  static QEMUMachine pc_machine_v0_13 = {

On Tue, Feb 26, 2013 at 11:53:28PM +0200, Michael S. Tsirkin wrote:
> QEMU 1.3 does not emulate the link auto negotiation, so if migrate to a
> 1.3 machine during link auto negotiation, the guest link will be set to down.
> Fix this by just disabling auto negotiation for 1.3 and older.
...
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 0af436c..6de2476 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -520,6 +520,10 @@ static QEMUMachine pc_machine_v0_14 = {
>              .driver   = "AC97",\
>              .property = "use_broken_id",\
>              .value    = stringify(1),\
> +        },{\
> +            .driver   = "e1000",\
> +            .property = "autonegotiation",\
> +            .value    = "off",\
>          }

Did you mean pc_i440fx_machine_v1_4 instead of pc_machine_v0_14?

Stefan