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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Ladi Prosek <lprosek@redhat.com>
Cc: dev@dpdk.org, yliu@fridaylinux.org, tiwei.bie@intel.com,
	jianfeng.tan@intel.com, Laszlo Ersek <lersek@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 1/4] vhost: prevent features to be changed while device is running
Date: Mon, 4 Dec 2017 15:20:53 +0100	[thread overview]
Message-ID: <b6143526-a820-8694-cc75-ca166b5e298a@redhat.com> (raw)
In-Reply-To: <CABdb736=5pK0QsJB7P3d7bMmT5wG0TL-APufmz21Lpp=YVijcQ@mail.gmail.com>



On 12/04/2017 03:17 PM, Ladi Prosek wrote:
> On Mon, Dec 4, 2017 at 3:08 PM, Maxime Coquelin
> <maxime.coquelin@redhat.com>  wrote:
>> As section 2.2 of the Virtio spec states about features
>> negotiation:
>> "During device initialization, the driver reads this and tells
>> the device the subset that it accepts. The only way to
>> renegotiate is to reset the device."
>>
>> This patch implements a check to prevent illegal features change
>> while the device is running.
>>
>> One exception is the VHOST_F_LOG_ALL feature bit, which is enabled
>> when live-migration is initiated. But this feature is not negotiated
>> with the Virtio driver, but directly with the Vhost master.
>>
>> Signed-off-by: Maxime Coquelin<maxime.coquelin@redhat.com>
>> ---
>>   lib/librte_vhost/vhost_user.c | 17 ++++++++++++++++-
>>   1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
>> index f4c7ce462..f51055ab2 100644
>> --- a/lib/librte_vhost/vhost_user.c
>> +++ b/lib/librte_vhost/vhost_user.c
>> @@ -183,7 +183,22 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t features)
>>                  return -1;
>>          }
>>
>> -       if ((dev->flags & VIRTIO_DEV_RUNNING) && dev->features != features) {
>> +       if (dev->features == features)
>> +               return 0;
>> +
>> +       if (dev->flags & VIRTIO_DEV_RUNNING) {
>> +               /*
>> +                * Error out if master tries to change features while device is
>> +                * in running state. The exception being VHOST_F_LOG_ALL, which
>> +                * is enabled when the live-migration starts.
>> +                */
>> +               if ((dev->features ^ features) & ~(1ULL >> VHOST_F_LOG_ALL)) {
> The 1 should be shifted to the left:
> 
>    1ULL << VHOST_F_LOG_ALL

Oh right, of course.

Thanks for spotting this.
Maxime

  reply	other threads:[~2017-12-04 14:21 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-04 14:08 [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ not negotiated Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 1/4] vhost: prevent features to be changed while device is running Maxime Coquelin
2017-12-04 14:17   ` Ladi Prosek
2017-12-04 14:20     ` Maxime Coquelin [this message]
2017-12-04 14:08 ` [dpdk-dev] [PATCH 2/4] vhost: propagate VHOST_USER_SET_FEATURES handling error Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 3/4] vhost: extract virtqueue cleaning and freeing functions Maxime Coquelin
2017-12-04 14:09 ` [dpdk-dev] [PATCH 4/4] vhost: destroy unused virtqueues when multiqueue not negotiated Maxime Coquelin
2017-12-04 14:27 ` [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ " Ladi Prosek
2017-12-04 14:48   ` Maxime Coquelin

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