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From: Stefan Hajnoczi <stefanha@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mst@redhat.com, lulu@redhat.com, kvm@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	rob.miller@broadcom.com, lingshan.zhu@intel.com,
	eperezma@redhat.com, hanand@xilinx.com, mhabets@solarflare.com,
	eli@mellanox.com, amorenoz@redhat.com,
	maxime.coquelin@redhat.com, sgarzare@redhat.com
Subject: Re: [RFC PATCH 00/24] Control VQ support in vDPA
Date: Thu, 24 Sep 2020 11:17:20 +0100	[thread overview]
Message-ID: <20200924101720.GR62770@stefanha-x1.localdomain> (raw)
In-Reply-To: <20200924032125.18619-1-jasowang@redhat.com>

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On Thu, Sep 24, 2020 at 11:21:01AM +0800, Jason Wang wrote:
> This series tries to add the support for control virtqueue in vDPA.

Please include documentation for both driver authors and vhost-vdpa
ioctl users. vhost-vdpa ioctls are only documented with a single
sentence. Please add full information on arguments, return values, and a
high-level explanation of the feature (like this cover letter) to
introduce the API.

What is the policy for using virtqueue groups? My guess is:
1. virtio_vdpa simply enables all virtqueue groups.
2. vhost_vdpa relies on userspace policy on how to use virtqueue groups.
   Are the semantics of virtqueue groups documented somewhere so
   userspace knows what to do? If a vDPA driver author decides to create
   N virtqueue groups, N/2 virtqueue groups, or just 1 virtqueue group,
   how will userspace know what to do?

Maybe a document is needed to describe the recommended device-specific
virtqueue groups that vDPA drivers should implement (e.g. "put the net
control vq into its own virtqueue group")?

This could become messy with guidelines. For example, drivers might be
shipped that aren't usable for certain use cases just because the author
didn't know that a certain virtqueue grouping is advantageous.

BTW I like how general this feature is. It seems to allow vDPA devices
to be split into sub-devices for further passthrough. Who will write the
first vDPA-on-vDPA driver? :)

Stefan

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  parent reply	other threads:[~2020-09-24 10:17 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-24  3:21 [RFC PATCH 00/24] Control VQ support in vDPA Jason Wang
2020-09-24  3:21 ` [RFC PATCH 01/24] vhost-vdpa: fix backend feature ioctls Jason Wang
2020-09-24  7:16   ` Eli Cohen
2020-09-24  7:26     ` Jason Wang
2020-09-24  7:38       ` Eli Cohen
2020-09-24  7:50   ` Michael S. Tsirkin
2020-09-24  8:28     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 02/24] vhost-vdpa: fix vqs leak in vhost_vdpa_open() Jason Wang
2020-09-24  7:48   ` Eli Cohen
2020-09-25 11:41     ` Jason Wang
2020-09-24  9:31   ` Michael S. Tsirkin
2020-09-25 11:27     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 03/24] vhost: move the backend feature bits to vhost_types.h Jason Wang
2020-09-24  3:21 ` [RFC PATCH 04/24] virtio-vdpa: don't set callback if virtio doesn't need it Jason Wang
2020-09-24  3:21 ` [RFC PATCH 05/24] vhost-vdpa: passing iotlb to IOMMU mapping helpers Jason Wang
2020-09-30 11:26   ` Eli Cohen
2020-10-09  2:01     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 06/24] vhost-vdpa: switch to use vhost-vdpa specific IOTLB Jason Wang
2020-09-30 12:02   ` Eli Cohen
2020-10-09  3:46     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 07/24] vdpa: add the missing comment for nvqs in struct vdpa_device Jason Wang
2020-09-24  3:21 ` [RFC PATCH 08/24] vdpa: introduce virtqueue groups Jason Wang
2020-09-28 15:44   ` Eugenio Perez Martin
2020-10-09  3:49     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 09/24] vdpa: multiple address spaces support Jason Wang
2020-10-01 13:21   ` Eli Cohen
2020-10-09  3:51     ` Jason Wang
2020-10-01 13:23   ` Eli Cohen
2020-10-09  3:52     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 10/24] vdpa: introduce config operations for associating ASID to a virtqueue group Jason Wang
2020-10-01 13:29   ` Eli Cohen
2020-10-09  3:56     ` Jason Wang
2020-10-12  6:59       ` Eli Cohen
2020-10-12  7:45         ` Jason Wang
2020-10-12  8:17           ` Eli Cohen
2020-10-13  5:40             ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 11/24] vhost_iotlb: split out IOTLB initialization Jason Wang
2020-09-24  3:21 ` [RFC PATCH 12/24] vhost: support ASID in IOTLB API Jason Wang
2020-09-24  3:21 ` [RFC PATCH 13/24] vhost-vdpa: introduce ASID based IOTLB Jason Wang
2020-09-29 14:40   ` Eugenio Perez Martin
2020-09-24  3:21 ` [RFC PATCH 14/24] vhost-vdpa: introduce uAPI to get the number of virtqueue groups Jason Wang
2020-09-24  3:21 ` [RFC PATCH 15/24] vhost-vdpa: introduce uAPI to get the number of address spaces Jason Wang
2020-09-24  3:21 ` [RFC PATCH 16/24] vhost-vdpa: uAPI to get virtqueue group id Jason Wang
2020-09-24  3:21 ` [RFC PATCH 17/24] vhost-vdpa: introduce uAPI to set group ASID Jason Wang
2020-09-24  3:21 ` [RFC PATCH 18/24] vhost-vdpa: support ASID based IOTLB API Jason Wang
2020-09-28 15:44   ` Eugenio Perez Martin
2020-10-09  3:59     ` Jason Wang
2020-09-24  3:21 ` [RFC PATCH 19/24] vdpa_sim: use separated iov for reading and writing Jason Wang
2020-09-24  3:21 ` [RFC PATCH 20/24] vdpa_sim: advertise VIRTIO_NET_F_MTU Jason Wang
2020-09-24  3:21 ` [RFC PATCH 21/24] vdpa_sim: advertise VIRTIO_NET_F_MAC Jason Wang
2020-09-24  3:21 ` [RFC PATCH 22/24] vdpa_sim: factor out buffer completion logic Jason Wang
2020-09-24  3:21 ` [RFC PATCH 23/24] vdpa_sim: filter destination mac address Jason Wang
2020-09-24  3:21 ` [RFC PATCH 24/24] vdpasim: control virtqueue support Jason Wang
2020-09-24 10:17 ` Stefan Hajnoczi [this message]
2020-09-25 11:36   ` [RFC PATCH 00/24] Control VQ support in vDPA Jason Wang

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