Re: [Qemu-devel] [PATCH] virtio-net: announce self by guest

[Jason Wang]

On 05/15/2014 04:28 PM, Michael S. Tsirkin wrote:
> Thanks, looks good.
> Some minor comments below,
>
> On Thu, May 15, 2014 at 03:16:47PM +0800, Jason Wang wrote:
>> It's hard to track all mac addresses and their configurations (e.g
>> vlan or ipv6) in qemu. Without those informations, it's impossible to
> s/those informations/this information/
>
>> build proper garp packet after migration. The only possible solution
>> to this is let guest (who knew all configurations) to do this.
> s/knew/knows/
>
>> So, this patch introduces a new readonly config status bit of virtio-net,
>> VIRTIO_NET_S_ANNOUNCE which is used to notify guest to announce
>> presence of its link through config update interrupt.When guest has
>> done the announcement, it should ack the notification through
>> VIRTIO_NET_CTRL_ANNOUNCE_ACK cmd. This feature is negotiated by a new
>> feature bit VIRTIO_NET_F_ANNOUNCE (which has already been supported by
>> Linux guest).
>>
>> During load, a counter of announcing rounds were set so that the after
> s/were/is/
> s/the after/after/

Will correct those typos.
>> the vm is running it can trigger rounds of config interrupts to notify
>> the guest to build and send the correct garps.
>>
>> Tested with ping to guest with vlan during migration. Without the
>> patch, lots of the packets were lost after migration. With the patch,
>> could not notice packet loss after migration.
> below changelog should go after ---, until the ack list.
>

Ok.
>> Reference:
>> RFC v2: https://lists.gnu.org/archive/html/qemu-devel/2014-04/msg01750.html
>> RFC v1: https://lists.gnu.org/archive/html/qemu-devel/2014-03/msg02648.html
>> V7:     https://lists.gnu.org/archive/html/qemu-devel/2013-03/msg01127.html
>>
>> Changes from RFC v2:
>> - use QEMU_CLOCK_VIRTUAL instead of QEMU_CLOCK_REALTIME
>> - compat self announce for 2.0 machine type
>>
>> Changes from RFC v1:
>> - clean VIRTIO_NET_S_ANNOUNCE bit during reset
>> - free announce timer during clean
>> - make announce work for non-vhost case
>>
>> Changes from V7:
>> - Instead of introducing a global method for each kind of nic, this
>>   version limits the changes to virtio-net itself.
>>
>> Cc: Liuyongan <address@hidden>
>> Cc: Amos Kong <address@hidden>
>> Signed-off-by: Jason Wang <address@hidden>
>> ---
>>  hw/net/virtio-net.c            |   48 
>> ++++++++++++++++++++++++++++++++++++++++
>>  include/hw/i386/pc.h           |    5 ++++
>>  include/hw/virtio/virtio-net.h |   16 +++++++++++++
>>  3 files changed, 69 insertions(+), 0 deletions(-)
>>
>> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
>> index 940a7cf..98d59e9 100644
>> --- a/hw/net/virtio-net.c
>> +++ b/hw/net/virtio-net.c
>> @@ -25,6 +25,7 @@
>>  #include "monitor/monitor.h"
>>  
>>  #define VIRTIO_NET_VM_VERSION    11
>> +#define VIRTIO_NET_ANNOUNCE_ROUNDS    3
>>  
>>  #define MAC_TABLE_ENTRIES    64
>>  #define MAX_VLAN    (1 << 12)   /* Per 802.1Q definition */
> I would make it  5 to be consistent with SELF_ANNOUNCE_ROUNDS
> in savevm.c
>
> in fact, let's move SELF_ANNOUNCE_ROUNDS to include/migration/vmstate.h
> and reuse it.

Ok.
>> @@ -99,6 +100,25 @@ static bool virtio_net_started(VirtIONet *n, uint8_t 
>> status)
>>          (n->status & VIRTIO_NET_S_LINK_UP) && vdev->vm_running;
>>  }
>>  
>> +static void virtio_net_announce_timer(void *opaque)
>> +{
>> +    VirtIONet *n = opaque;
>> +    VirtIODevice *vdev = VIRTIO_DEVICE(n);
>> +
>> +    if (n->announce &&
> I would make it > 0 here, just in case it becomes negative as a result
> of some bug.

Sure.
>> +        virtio_net_started(n, vdev->status) &&
>> +        vdev->guest_features & (0x1 << VIRTIO_NET_F_GUEST_ANNOUNCE) &&
>> +        vdev->guest_features & (0x1 << VIRTIO_NET_F_CTRL_VQ)) {
>> +
>> +        n->announce--;
>> +        n->status |= VIRTIO_NET_S_ANNOUNCE;
>> +        virtio_notify_config(vdev);
>> +    } else {
>> +        timer_del(n->announce_timer);
> why do this here?
>
>> +        n->announce = 0;
> why is this here?
>

If guest shuts down the device, there's no need to do the announcing.
>> +    }
>> +}
>> +
>>  static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
>>  {
>>      VirtIODevice *vdev = VIRTIO_DEVICE(n);
>> @@ -147,6 +167,8 @@ static void virtio_net_set_status(struct VirtIODevice 
>> *vdev, uint8_t status)
>>  
>>      virtio_net_vhost_status(n, status);
>>  
>> +    virtio_net_announce_timer(n);
>> +
> why do this here? why not right after we set announce counter?

The reasons are:

- The counters were set in load, but the device is not running so we
could not inject the interrupt at that time.
- We can stop the progress when guest is shutting down the device.
>
>>      for (i = 0; i < n->max_queues; i++) {
>>          q = &n->vqs[i];
>>  
>> @@ -322,6 +344,9 @@ static void virtio_net_reset(VirtIODevice *vdev)
>>      n->nobcast = 0;
>>      /* multiqueue is disabled by default */
>>      n->curr_queues = 1;
>> +    timer_del(n->announce_timer);
>> +    n->announce = 0;
>> +    n->status &= ~VIRTIO_NET_S_ANNOUNCE;
>>  
>>      /* Flush any MAC and VLAN filter table state */
>>      n->mac_table.in_use = 0;
>> @@ -731,6 +756,22 @@ static int virtio_net_handle_vlan_table(VirtIONet *n, 
>> uint8_t cmd,
>>      return VIRTIO_NET_OK;
>>  }
>>  
>> +static int virtio_net_handle_announce(VirtIONet *n, uint8_t cmd,
>> +                                      struct iovec *iov, unsigned int 
>> iov_cnt)
>> +{
>> +    if (cmd == VIRTIO_NET_CTRL_ANNOUNCE_ACK) {
>> +        n->status &= ~VIRTIO_NET_S_ANNOUNCE;
>> +        if (n->announce) {
> I would make it > 0 here, just in case it becomes negative as a result
> of some bug.

Ok.
>> +            timer_mod(n->announce_timer,
>> +                      qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 50 +
>> +                      (VIRTIO_NET_ANNOUNCE_ROUNDS - n->announce - 1) * 100);
> savevm.c has this code, and a comment:
>         /* delay 50ms, 150ms, 250ms, ... */
>       50 + (SELF_ANNOUNCE_ROUNDS - count - 1) * 100
>
> how about an API in include/migration/vmstate.h
>
> static inline
> int64_t self_announce_delay(int round)
> {
>       assert(round < SELF_ANNOUNCE_ROUNDS && round > 0);
>         /* delay 50ms, 150ms, 250ms, ... */
>       return 50 + (SELF_ANNOUNCE_ROUNDS - round - 1) * 100;
> }
>
> or something to this end.
>

Good idea, will do this.
>> +        }
>> +        return VIRTIO_NET_OK;
>> +    } else {
>> +        return VIRTIO_NET_ERR;
>> +    }
>> +}
>> +
>>  static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
>>                                  struct iovec *iov, unsigned int iov_cnt)
>>  {
>> @@ -794,6 +835,8 @@ static void virtio_net_handle_ctrl(VirtIODevice *vdev, 
>> VirtQueue *vq)
>>              status = virtio_net_handle_mac(n, ctrl.cmd, iov, iov_cnt);
>>          } else if (ctrl.class == VIRTIO_NET_CTRL_VLAN) {
>>              status = virtio_net_handle_vlan_table(n, ctrl.cmd, iov, 
>> iov_cnt);
>> +        } else if (ctrl.class == VIRTIO_NET_CTRL_ANNOUNCE) {
>> +            status = virtio_net_handle_announce(n, ctrl.cmd, iov, iov_cnt);
>>          } else if (ctrl.class == VIRTIO_NET_CTRL_MQ) {
>>              status = virtio_net_handle_mq(n, ctrl.cmd, iov, iov_cnt);
>>          } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) {
>> @@ -1451,6 +1494,7 @@ static int virtio_net_load(QEMUFile *f, void *opaque, 
>> int version_id)
>>          qemu_get_subqueue(n->nic, i)->link_down = link_down;
>>      }
>>  
>> +    n->announce = VIRTIO_NET_ANNOUNCE_ROUNDS;
> Well if virtio_net_handle_announce runs now it will start timer
> in the past, right?
> This seems wrong.

Not sure I get the case. When in virtio_net_load() the vm is not even
running so looks like virtio_net_handle_announce() could not run in the
same time.
>
>>      return 0;
>>  }
>>  
>> @@ -1562,6 +1606,8 @@ static void virtio_net_device_realize(DeviceState 
>> *dev, Error **errp)
>>      qemu_macaddr_default_if_unset(&n->nic_conf.macaddr);
>>      memcpy(&n->mac[0], &n->nic_conf.macaddr, sizeof(n->mac));
>>      n->status = VIRTIO_NET_S_LINK_UP;
>> +    n->announce_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
>> +                                     virtio_net_announce_timer, n);
>>  
>>      if (n->netclient_type) {
>>          /*
>> @@ -1642,6 +1688,8 @@ static void virtio_net_device_unrealize(DeviceState 
>> *dev, Error **errp)
>>          }
>>      }
>>  
>> +    timer_del(n->announce_timer);
>> +    timer_free(n->announce_timer);
>>      g_free(n->vqs);
>>      qemu_del_nic(n->nic);
>>      virtio_cleanup(vdev);
>> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
>> index 32a7687..f93b427 100644
>> --- a/include/hw/i386/pc.h
>> +++ b/include/hw/i386/pc.h
>> @@ -271,6 +271,11 @@ bool e820_get_entry(int, uint32_t, uint64_t *, uint64_t 
>> *);
>>              .driver   = "apic",\
>>              .property = "version",\
>>              .value    = stringify(0x11),\
>> +        },\
>> +        {\
>> +            .driver   = "virtio-net-pci",\
>> +            .property = "guest_announce",\
>> +            .value    = "off",\
>>          }
>>  
>>  #define PC_COMPAT_1_7 \
>> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
>> index 4b32440..ca1a9c5 100644
>> --- a/include/hw/virtio/virtio-net.h
>> +++ b/include/hw/virtio/virtio-net.h
>> @@ -49,12 +49,14 @@
>>  #define VIRTIO_NET_F_CTRL_RX    18      /* Control channel RX mode support 
>> */
>>  #define VIRTIO_NET_F_CTRL_VLAN  19      /* Control channel VLAN filtering */
>>  #define VIRTIO_NET_F_CTRL_RX_EXTRA 20   /* Extra RX mode control support */
>> +#define VIRTIO_NET_F_GUEST_ANNOUNCE 21  /* Guest can announce itself */
>>  #define VIRTIO_NET_F_MQ         22      /* Device supports Receive Flow
>>                                           * Steering */
>>  
>>  #define VIRTIO_NET_F_CTRL_MAC_ADDR   23 /* Set MAC address */
>>  
>>  #define VIRTIO_NET_S_LINK_UP    1       /* Link is up */
>> +#define VIRTIO_NET_S_ANNOUNCE   2       /* Announcement is needed */
>>  
>>  #define TX_TIMER_INTERVAL 150000 /* 150 us */
>>  
>> @@ -193,6 +195,8 @@ typedef struct VirtIONet {
>>      char *netclient_name;
>>      char *netclient_type;
>>      uint64_t curr_guest_offloads;
>> +    QEMUTimer *announce_timer;
>> +    int announce;
>
> rename announce_counter pls.
>

Ok.
>>  } VirtIONet;
>>  
>>  #define VIRTIO_NET_CTRL_MAC    1
>> @@ -213,6 +217,17 @@ typedef struct VirtIONet {
>>   #define VIRTIO_NET_CTRL_VLAN_DEL             1
>>  
>>  /*
>> + * Control link announce acknowledgement
>> + *
> bunch of typos and vagueness below
>
>> + * The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate that
>> + * driver has recevied the notification and device would clear the
>> + * VIRTIO_NET_S_ANNOUNCE bit in the status filed after it received
>> + * this command.
> fixed version:
>
> VIRTIO_NET_S_ANNOUNCE bit in the status field requests link
> announcement from guest driver. The driver is notified by config space change
> interrupt.  The command VIRTIO_NET_CTRL_ANNOUNCE_ACK is used to indicate
> that the driver has received the notification. It makes the device clear the
> bit VIRTIO_NET_S_ANNOUNCE in the status field.
>

Sorry, look like I just copied those from a very old RFC. Will correct
this. Thanks
>> + */
>> +#define VIRTIO_NET_CTRL_ANNOUNCE       3
>> + #define VIRTIO_NET_CTRL_ANNOUNCE_ACK         0
>> +
>> +/*
>>   * Control Multiqueue
>>   *
>>   * The command VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET
>> @@ -251,6 +266,7 @@ struct virtio_net_ctrl_mq {
>>          DEFINE_PROP_BIT("guest_tso6", _state, _field, 
>> VIRTIO_NET_F_GUEST_TSO6, true), \
>>          DEFINE_PROP_BIT("guest_ecn", _state, _field, 
>> VIRTIO_NET_F_GUEST_ECN, true), \
>>          DEFINE_PROP_BIT("guest_ufo", _state, _field, 
>> VIRTIO_NET_F_GUEST_UFO, true), \
>> +        DEFINE_PROP_BIT("guest_announce", _state, _field, 
>> VIRTIO_NET_F_GUEST_ANNOUNCE, true), \
>>          DEFINE_PROP_BIT("host_tso4", _state, _field, 
>> VIRTIO_NET_F_HOST_TSO4, true), \
>>          DEFINE_PROP_BIT("host_tso6", _state, _field, 
>> VIRTIO_NET_F_HOST_TSO6, true), \
>>          DEFINE_PROP_BIT("host_ecn", _state, _field, VIRTIO_NET_F_HOST_ECN, 
>> true), \
>> -- 
>> 1.7.1