From: Ladi Prosek <lprosek@redhat.com>
To: Maxime Coquelin <maxime.coquelin@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 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ not negotiated
Date: Mon, 4 Dec 2017 15:27:21 +0100 [thread overview]
Message-ID: <CABdb737u-dBvxTfOq2=kEUBrBAweASF85QQfbniYPDaZotN-Bw@mail.gmail.com> (raw)
In-Reply-To: <20171204140900.7906-1-maxime.coquelin@redhat.com>
On Mon, Dec 4, 2017 at 3:08 PM, Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
> Having QEMU started with mq=on but guest driver not negotiating
> VIRTIO_NET_F_MQ feature ends up in the vhost device to never
> start. Indeed, more queues are created in the vhost backend than
> configured.
>
> Guest drivers known to not advertise the VIRTIO_NET_F_MQ feature are
> iPXE and OVMF Virtio-net drivers.
>
> Queues are created because before starting the guest, QEMU sends
> VHOST_USER_SET_VRING_CALL requests for all queues declared in QEMU
> command line. Also, once Virtio features negotiated, QEMU sends
> VHOST_USER_SET_VRING_ENABLE requests to disable all but the first
> queue pair.
>
> This series fixes this by destroying all but first queue pair in
> the backend if VIRTIO_NET_F_MQ isn't negotiated.
The destroyed queue pairs will be re-created when an MQ-enabled driver
takes over later on, though, is that correct?
iPXE and OVMF virtio-net drivers will typically not be the last ones
driving the device. They will likely load an OS equipped with a driver
that negotiates the MQ feature. Thanks!
> First patches
> makes sure that VHOST_USER_SET_FEATURES request doesn't change
> Virtio features while the device is running, which should never
> happen as per the Virtio spec. This helps to make sure vitqueues
> aren't destroyed while being processed, but also protect from
> other illegal features changes (e.g. VIRTIO_NET_F_MRG_RXBUF).
>
> Maxime Coquelin (4):
> vhost: prevent features to be changed while device is running
> vhost: propagate VHOST_USER_SET_FEATURES handling error
> vhost: extract virtqueue cleaning and freeing functions
> vhost: destroy unused virtqueues when multiqueue not negotiated
>
> lib/librte_vhost/vhost.c | 22 ++++++++++++----------
> lib/librte_vhost/vhost.h | 3 +++
> lib/librte_vhost/vhost_user.c | 40 ++++++++++++++++++++++++++++++++++++++--
> 3 files changed, 53 insertions(+), 12 deletions(-)
>
> --
> 2.14.3
>
next prev parent reply other threads:[~2017-12-04 14:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-04 14:08 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
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 ` Ladi Prosek [this message]
2017-12-04 14:48 ` [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ " Maxime Coquelin
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