+1 Jan
> -----Original Message----- > From: Kevin Traynor [mailto:[email protected]] > Sent: Friday, 24 November, 2017 17:11 > To: Mark Kavanagh <[email protected]>; [email protected] > Cc: [email protected]; Flavio Leitner <[email protected]>; Franck > Baudin <[email protected]>; Mooney, Sean K > <[email protected]>; Ilya Maximets <[email protected]>; Ian Stokes > <[email protected]>; Loftus, Ciara > <[email protected]>; Darrell Ball <[email protected]>; Aaron Conole > <[email protected]>; Jan Scheurich > <[email protected]> > Subject: Re: [ovs-dev] [PATCH 2/2] netdev-dpdk: add support for vhost IOMMU > feature > > On 11/16/2017 11:01 AM, Mark Kavanagh wrote: > > DPDK v17.11 introduces support for the vHost IOMMU feature. > > This is a security feature, that restricts the vhost memory > > that a virtio device may access. > > > > This feature also enables the vhost REPLY_ACK protocol, the > > implementation of which is known to work in newer versions of > > QEMU (i.e. v2.10.0), but is buggy in older versions (v2.7.0 - > > v2.9.0, inclusive). As such, the feature is disabled by default > > in (and should remain so, for the aforementioned older QEMU > > verions). Starting with QEMU v2.9.1, vhost-iommu-support can > > safely be enabled, even without having an IOMMU device, with > > no performance penalty. > > > > This patch adds a new vhost port option, vhost-iommu-support, > > to allow enablement of the vhost IOMMU feature: > > > > $ ovs-vsctl add-port br0 vhost-client-1 \ > > -- set Interface vhost-client-1 type=dpdkvhostuserclient \ > > options:vhost-server-path=$VHOST_USER_SOCKET_PATH \ > > options:vhost-iommu-support=true > > > > Hi Mark, All, > > I'm thinking about this and whether the current approach provides more > than what is actually needed by users at the cost of making the user > interface more complex. > > As an alternative, how about having a global other_config (to be set > like vhost-socket-dir can be) for this instead of having to set it for > each individual interface. It would mean that it would only have to be > set once, instead of having this (ugly?!) option every time a vhost port > is added, so it's a less intrusive change and I can't really think that > a user would require to do this per vhostclient interface??? It's pain > to have to add this at all for a bug in QEMU and I'm sure in 1/2/3 years > time someone will say that users could still be using QEMU < 2.9.1 and > we can't remove it, so it would be nice to keep it as discreet as > possible as we're going to be stuck with it for a while. > > I assume that a user would only use one version of QEMU at a time and > would either want or not want this feature. In the worst case, if that > proved completely wrong in the future, then a per interface override > could easily be added. Once there's a way to maintain backwards > compatibility (which there would be) I'd rather err on the side of > introducing just enough enough functionality over increasing complexity > for the user. > > What do you think? > > thanks, > Kevin. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
