From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Tiwei Bie <tiwei.bie@intel.com>
Cc: dev@dpdk.org, yliu@fridaylinux.org, jianfeng.tan@intel.com,
lprosek@redhat.com, lersek@redhat.com
Subject: Re: [dpdk-dev] [PATCH v4 4/4] vhost: destroy unused virtqueues when multiqueue not negotiated
Date: Wed, 13 Dec 2017 09:14:51 +0100 [thread overview]
Message-ID: <63b4063f-1994-8ce2-2682-776e44ee608a@redhat.com> (raw)
In-Reply-To: <20171213031615.t7rh2ccjf5gml73h@debian-xvivbkq>
On 12/13/2017 04:16 AM, Tiwei Bie wrote:
> On Mon, Dec 11, 2017 at 04:15:03PM +0100, Maxime Coquelin wrote:
>> QEMU sends VHOST_USER_SET_VRING_CALL requests for all queues
>> declared in QEMU command line before the guest is started.
>> It has the effect in DPDK vhost-user backend to allocate vrings
>> for all queues declared by QEMU.
>>
>> If the first driver being used does not support multiqueue,
>> the device never changes to VIRTIO_DEV_RUNNING state as only
>> the first queue pair is initialized. One driver impacted by
>> this bug is virtio-net's iPXE driver which does not support
>> VIRTIO_NET_F_MQ feature.
>>
>> It is safe to destroy unused virtqueues in SET_FEATURES request
>> handler, as it is ensured the device is not in running state
>> at this stage, so virtqueues aren't being processed.
>>
>> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
>> ---
>> lib/librte_vhost/vhost_user.c | 18 ++++++++++++++++++
>> 1 file changed, 18 insertions(+)
>>
>> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
>> index 471b1612c..d5ca1ac90 100644
>> --- a/lib/librte_vhost/vhost_user.c
>> +++ b/lib/librte_vhost/vhost_user.c
>> @@ -216,6 +216,24 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t features)
>> (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ? "on" : "off",
>> (dev->features & (1ULL << VIRTIO_F_VERSION_1)) ? "on" : "off");
>>
>> + if (!(dev->features & (1ULL << VIRTIO_NET_F_MQ))) {
>> + /*
>> + * Remove all but first queue pair if MQ hasn't been
>> + * negotiated. This is safe because the device is not
>> + * running at this stage.
>> + */
>> + while (dev->nr_vring > 2) {
>> + struct vhost_virtqueue *vq;
>> +
>> + vq = dev->virtqueue[--dev->nr_vring];
>> + if (!vq)
>> + continue;
>> +
>> + cleanup_vq(vq, 1);
>> + free_vq(vq);
>
> Hi,
>
> Sorry, I didn't look into this patch in last version.
Don't be sorry, thanks for catching this bug.
> The freed dev->virtqueue[$idx] also needs to be zeroed.
> Otherwise, it won't be allocated in the future due to the
> below check in vhost_user_check_and_alloc_queue_pair(),
> and the freed memory will be used again.
>
> /*
> * Allocate a queue pair if it hasn't been allocated yet
> */
> static int
> vhost_user_check_and_alloc_queue_pair(struct virtio_net *dev, VhostUserMsg *msg)
> {
> ........
>
> if (dev->virtqueue[vring_idx])
> return 0;
>
> return alloc_vring_queue(dev, vring_idx);
> }
You are right, I'll post v5 setting dev->virtqueue[$idx] to NULL after
free_vq() call.
Thanks for the review,
Maxime
> Best regards,
> Tiwei Bie
>
>> + }
>> + }
>> +
>> return 0;
>> }
>>
>> --
>> 2.14.3
>>
next prev parent reply other threads:[~2017-12-13 8:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-11 15:14 [dpdk-dev] [PATCH v4 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ " Maxime Coquelin
2017-12-11 15:15 ` [dpdk-dev] [PATCH v4 1/4] vhost: prevent features to be changed while device is running Maxime Coquelin
2017-12-11 15:15 ` [dpdk-dev] [PATCH v4 2/4] vhost: propagate VHOST_USER_SET_FEATURES handling error Maxime Coquelin
2017-12-11 15:15 ` [dpdk-dev] [PATCH v4 3/4] vhost: extract virtqueue cleaning and freeing functions Maxime Coquelin
2017-12-11 15:15 ` [dpdk-dev] [PATCH v4 4/4] vhost: destroy unused virtqueues when multiqueue not negotiated Maxime Coquelin
2017-12-13 3:16 ` Tiwei Bie
2017-12-13 8:14 ` Maxime Coquelin [this message]
2017-12-11 16:12 ` [dpdk-dev] [PATCH v4 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ " Laszlo Ersek
2017-12-12 6:34 ` Ladi Prosek
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