[dpdk-dev] [PATCH] vhost-user: enable virtio 1.0
Michael S. Tsirkin
mst at redhat.com
Fri Oct 16 08:20:18 CEST 2015
On Fri, Oct 16, 2015 at 10:24:38AM +0800, Yuanhan Liu wrote:
> On Thu, Oct 15, 2015 at 04:18:59PM +0300, Michael S. Tsirkin wrote:
> > On Thu, Oct 15, 2015 at 02:08:39PM +0300, Marcel Apfelbaum wrote:
> > > Make vhost-user virtio 1.0 compatible by adding it to the
> > > supported features and keeping the header length
> > > the same as for mergeable RX buffers.
> > >
> > > Signed-off-by: Marcel Apfelbaum <marcel at redhat.com>
>
> Marcel, that's actually one of my TODOs in this quarter. So, thank
> you! :)
>
> >
> > Looks good to me
> >
> > Acked-by: Michael S. Tsirkin <mst at redhat.com>
> >
> > Just one question: dpdk is only supported on little-endian
> > platforms at the moment, right?
>
> AFAIK, yes. But you might also see that there are some patch to add
> ARM arch support showed up in the mailing list few weeks ago.
Luckily, that's also little-endian.
> > virtio 1 spec requires little endian.
>
> I made a quick list of the difference between virtio v0.95 and v1.0
> months ago just by reading your kernel commits of adding v1.0 support:
>
> +-------------------+-----------------+------------------------------+
> | | v0.95 | v1.0 |
> +-------------------+-----------------+------------------------------+
> 1) | features bits | 32 | 64 |
> +-------------------+-----------------+------------------------------+
> 2) | Endianness | nature | Little Endian |
> +-------------------+-----------------+------------------------------+
> 3) | vring space | contiguous | avail and used buffer could |
> | | memory | be on a separate memory |
And desc buffer, too.
> +-------------------+-----------------+------------------------------+
> 4) | FEATURE_OK status | No | Yes |
> +-------------------+-----------------+------------------------------+
>
>
>
> For 1), I guess we have been using 64 bit for storing features bits
> for vhost since long time ago. So, there should be no extra effort.
>
> For 2), as stated, there might be no issue as far as DPDK is little
> endian only. But we'd better add a wrapper for that, as it seems
> adding big endian support would come in near future.
OK, but it probably doesn't
> For 3), are we actually doing that? I just saw that there is a kernel
> patch to introduce two functions for getting the avail and used buffer
> address, respectively. But I didn't see that the two buffer are
> allocated in non-contiguous memory.
That will soon happen, anyone claiming support for virtio 1
But vhost user already sends each ring part separately.
Does dpdk assume they are contigious?
> For 4), it's a work we should do at virtio PMD driver. And it seems
> that there are far more work need to be done at virtio PDM driver than
> at vhost lib, say, adding the virtio morden PCI support.
>
> Besides those 4 differs, did I miss anyting?
>From virtio PMD point of view? There are more
differences. The trick is to find "legacy interface"
sections and go over them, that compares 0.9 to 1.0.
>
> BTW, since we already have same TODOs, I guess it'd be better to
> share what we have in our TODO list. Here are what I got till the
> time writing this email (in order of priority):
>
> - a vhost performance issue (it might last long; it might not).
>
> - vhost-user live migration support
>
> - virtio 1.0 support, including PMD and vhost lib (and you guys have
> already done that :)
>
> Thanks.
This patch only touches the vhost lib, though.
> --yliu
>
>
> > > ---
> > >
> > > To be applied on top of:
> > > [dpdk-dev] [PATCH v6 00/13] vhost-user multiple queues enabling
> > >
> > > Thanks,
> > > Marcel
> > >
> > > lib/librte_vhost/virtio-net.c | 15 ++++++++-------
> > > 1 file changed, 8 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
> > > index a51327d..ee4650e 100644
> > > --- a/lib/librte_vhost/virtio-net.c
> > > +++ b/lib/librte_vhost/virtio-net.c
> > > @@ -75,6 +75,7 @@ static struct virtio_net_config_ll *ll_root;
> > > (1ULL << VIRTIO_NET_F_CTRL_VQ) | \
> > > (1ULL << VIRTIO_NET_F_CTRL_RX) | \
> > > (1ULL << VIRTIO_NET_F_MQ) | \
> > > + (1ULL << VIRTIO_F_VERSION_1) | \
> > > (1ULL << VHOST_F_LOG_ALL) | \
> > > (1ULL << VHOST_USER_F_PROTOCOL_FEATURES))
> > > static uint64_t VHOST_FEATURES = VHOST_SUPPORTED_FEATURES;
> > > @@ -477,17 +478,17 @@ set_features(struct vhost_device_ctx ctx, uint64_t *pu)
> > > return -1;
> > >
> > > dev->features = *pu;
> > > - if (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) {
> > > - LOG_DEBUG(VHOST_CONFIG,
> > > - "(%"PRIu64") Mergeable RX buffers enabled\n",
> > > - dev->device_fh);
> > > + if (dev->features &
> > > + ((1 << VIRTIO_NET_F_MRG_RXBUF) | (1ULL << VIRTIO_F_VERSION_1))) {
> > > vhost_hlen = sizeof(struct virtio_net_hdr_mrg_rxbuf);
> > > } else {
> > > - LOG_DEBUG(VHOST_CONFIG,
> > > - "(%"PRIu64") Mergeable RX buffers disabled\n",
> > > - dev->device_fh);
> > > vhost_hlen = sizeof(struct virtio_net_hdr);
> > > }
> > > + LOG_DEBUG(VHOST_CONFIG,
> > > + "(%"PRIu64") Mergeable RX buffers %s, virtio 1 %s\n",
> > > + dev->device_fh,
> > > + (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ? "on" : "off",
> > > + (dev->features & (1ULL << VIRTIO_F_VERSION_1)) ? "on" : "off");
> > >
> > > for (i = 0; i < dev->virt_qp_nb; i++) {
> > > uint16_t base_idx = i * VIRTIO_QNUM;
> > > --
> > > 2.1.0
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