Re: [Qemu-devel] [PATCH] e1000/rtl8139: update HMP NIC when every bit is written

[Vlad Yasevich <vyasevic@redhat.com>]

On 11/08/2013 10:43 PM, Amos Kong wrote:
> On Fri, Nov 08, 2013 at 02:42:27PM -0500, Vlad Yasevich wrote:
>> What about this approach?  This only updates the monitory when all the
>> bits have been written to.
>
> Hi Vlad,
>
> Looks good to me.
>
> Using this patch, we don't need to care the writing order.
> If we add event notify in future, it can reduce the noise
> event.
>
> BTW, can we use a tmp buffer to record the new mac (changing is unfinished),
> and write the new mac to registers until all bits is written?

I've thought about this as well, but I am not sure what it would buy us
and what's the best way to do it.

At first I thought that we could have a function local static that we
could accumulate into.  But then Michael mentioned migration and what
happens if we migrate in middle of the mac change?

So we put into the device, but then it isn't much different then what
we have now with the possible exception that the mac change happens
slightly "more atomically". :)  For this, it might make more sense to
temporarily stop the link when the mac address change is happening.

-vlad

>
> Amos
>
>> -vlad
>>
>> -- >8 --
>> Subject: [PATCH] e1000/rtl8139: update HMP NIC when every bit is written
>
> Subject: [PATCH] e1000/rtl8139: update HMP NIC when all bits are written
>
>> We currently just update the HMP NIC info when the last bit of macaddr
>> is written. This assumes that guest driver will write all the macaddr
>> from bit 0 to bit 5 when it changes the macaddr, this is the current
>> behavior of linux driver (e1000/rtl8139cp), but we can't do this
>> assumption.
>>
>> The macaddr that is used for rx-filter will be updated when every bit
>> is changed. This patch updates the e1000/rtl8139 nic to update HMP NIC
>> info when every bit has been changed. It will be same as virtio-net.
>>
>> Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
>> ---
>>   hw/net/e1000.c   | 17 ++++++++++++++++-
>>   hw/net/rtl8139.c | 14 +++++++++-----
>>   2 files changed, 25 insertions(+), 6 deletions(-)
>>
>> diff --git a/hw/net/e1000.c b/hw/net/e1000.c
>> index 8387443..a5967ed 100644
>> --- a/hw/net/e1000.c
>> +++ b/hw/net/e1000.c
>> @@ -149,6 +149,10 @@ typedef struct E1000State_st {
>>   #define E1000_FLAG_AUTONEG (1 << E1000_FLAG_AUTONEG_BIT)
>>   #define E1000_FLAG_MIT (1 << E1000_FLAG_MIT_BIT)
>>       uint32_t compat_flags;
>> +    uint32_t mac_changed;
>> +#define E1000_RA0_CHANGED 0
>> +#define E1000_RA1_CHANGED 1
>> +#define E1000_RA_ALL_CHANGED (E1000_RA0_CHANGED|E1000_RA1_CHANGED)
>>   } E1000State;
>>
>>   #define TYPE_E1000 "e1000"
>> @@ -402,6 +406,7 @@ static void e1000_reset(void *opaque)
>>           d->mac_reg[RA + 1] |= (i < 2) ? macaddr[i + 4] << (8 * i) : 0;
>>       }
>>       qemu_format_nic_info_str(qemu_get_queue(d->nic), macaddr);
>> +    d->mac_changed = 0;
>>   }
>>
>>   static void
>> @@ -1106,10 +1111,20 @@ mac_writereg(E1000State *s, int index, uint32_t val)
>>
>>       s->mac_reg[index] = val;
>>
>> -    if (index == RA + 1) {
>> +    switch (index) {
>> +    case RA:
>> +        s->mac_changed |= E1000_RA0_CHANGED;
>> +        break;
>> +    case (RA + 1):
>> +        s->mac_changed |= E1000_RA1_CHANGED;
>> +        break;
>> +    }
>> +
>> +    if (s->mac_changed ==  E1000_RA_ALL_CHANGED) {
>>           macaddr[0] = cpu_to_le32(s->mac_reg[RA]);
>>           macaddr[1] = cpu_to_le32(s->mac_reg[RA + 1]);
>>           qemu_format_nic_info_str(qemu_get_queue(s->nic), (uint8_t *)macaddr);
>> +	s->mac_changed = 0;
>>       }
>>   }
>>
>> diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
>> index 5329f44..6dac10c 100644
>> --- a/hw/net/rtl8139.c
>> +++ b/hw/net/rtl8139.c
>> @@ -476,6 +476,8 @@ typedef struct RTL8139State {
>>
>>       uint16_t CpCmd;
>>       uint8_t  TxThresh;
>> +    uint8_t  mac_changed;
>> +#define RTL8139_MAC_CHANGED_ALL 0x3F
>>
>>       NICState *nic;
>>       NICConf conf;
>> @@ -1215,6 +1217,7 @@ static void rtl8139_reset(DeviceState *d)
>>       /* restore MAC address */
>>       memcpy(s->phys, s->conf.macaddr.a, 6);
>>       qemu_format_nic_info_str(qemu_get_queue(s->nic), s->phys);
>> +    s->mac_changed = 0;
>>
>>       /* reset interrupt mask */
>>       s->IntrStatus = 0;
>> @@ -2741,12 +2744,13 @@ static void rtl8139_io_writeb(void *opaque, uint8_t addr, uint32_t val)
>>
>>       switch (addr)
>>       {
>> -        case MAC0 ... MAC0+4:
>> -            s->phys[addr - MAC0] = val;
>> -            break;
>> -        case MAC0+5:
>> +        case MAC0 ... MAC0+5:
>>               s->phys[addr - MAC0] = val;
>> -            qemu_format_nic_info_str(qemu_get_queue(s->nic), s->phys);
>> +            s->mac_changed |= (1 << (addr - MAC0));
>> +            if (s->mac_changed == RTL8139_MAC_CHANGED_ALL) {
>> +                qemu_format_nic_info_str(qemu_get_queue(s->nic), s->phys);
>> +                s->mac_changed = 0;
>> +            }
>>               break;
>>           case MAC0+6 ... MAC0+7:
>>               /* reserved */
>> --
>> 1.8.4.2