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Re: [Qemu-devel] [PATCH 3/4] vhost-user: add protocol feature negotiatio
From: |
Flavio Leitner |
Subject: |
Re: [Qemu-devel] [PATCH 3/4] vhost-user: add protocol feature negotiation |
Date: |
Fri, 17 Jul 2015 15:14:33 -0300 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Fri, Jul 17, 2015 at 05:09:38PM +0300, Michael S. Tsirkin wrote:
> Support a separate bitmask for vhost-user protocol features,
> and messages to get/set protocol features.
>
> Invoke them at init.
>
> No features are defined yet.
>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
> include/hw/virtio/vhost.h | 1 +
> hw/net/vhost_net.c | 2 ++
> hw/virtio/vhost-user.c | 52
> +++++++++++++++++++++++++++++++++++++++++++++++
> docs/specs/vhost-user.txt | 37 +++++++++++++++++++++++++++++++++
> 4 files changed, 92 insertions(+)
>
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index dd51050..6467c73 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -47,6 +47,7 @@ struct vhost_dev {
> unsigned long long features;
> unsigned long long acked_features;
> unsigned long long backend_features;
> + unsigned long long protocol_features;
> bool started;
> bool log_enabled;
> unsigned long long log_size;
> diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> index 5c1d11f..c864237 100644
> --- a/hw/net/vhost_net.c
> +++ b/hw/net/vhost_net.c
> @@ -152,8 +152,10 @@ struct vhost_net *vhost_net_init(VhostNetOptions
> *options)
> net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend)
> ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR);
> net->backend = r;
> + net->dev.protocol_features = 0;
> } else {
> net->dev.backend_features = 0;
> + net->dev.protocol_features = 0;
> net->backend = -1;
> }
> net->nc = options->net_backend;
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 5a83d00..c4428a1 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -25,6 +25,9 @@
>
> #define VHOST_MEMORY_MAX_NREGIONS 8
>
> +#define VHOST_USER_F_PROTOCOL_FEATURES 30
> +#define VHOST_USER_PROTOCOL_FEATURE_MASK 0x0ULL
> +
> typedef enum VhostUserRequest {
> VHOST_USER_NONE = 0,
> VHOST_USER_GET_FEATURES = 1,
> @@ -41,6 +44,8 @@ typedef enum VhostUserRequest {
> VHOST_USER_SET_VRING_KICK = 12,
> VHOST_USER_SET_VRING_CALL = 13,
> VHOST_USER_SET_VRING_ERR = 14,
> + VHOST_USER_GET_PROTOCOL_FEATURES = 15,
> + VHOST_USER_SET_PROTOCOL_FEATURES = 26,
I think you meant 16 here.
fbl
> VHOST_USER_MAX
> } VhostUserRequest;
>
> @@ -332,10 +337,57 @@ static int vhost_user_call(struct vhost_dev *dev,
> unsigned long int request,
>
> static int vhost_user_init(struct vhost_dev *dev, void *opaque)
> {
> + VhostUserMsg msg = { 0 };
> + int err;
> +
> assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
>
> dev->opaque = opaque;
>
> + msg.request = VHOST_USER_GET_FEATURES;
> + msg.flags = VHOST_USER_VERSION;
> + msg.size = 0;
> +
> + err = vhost_user_write(dev, &msg, NULL, 0);
> + if (err < 0) {
> + return err;
> + }
> +
> + err = vhost_user_read(dev, &msg);
> + if (err < 0) {
> + return err;
> + }
> +
> + if (__virtio_has_feature(msg.u64, VHOST_USER_F_PROTOCOL_FEATURES)) {
> + dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
> +
> + msg.request = VHOST_USER_GET_PROTOCOL_FEATURES;
> + msg.flags = VHOST_USER_VERSION;
> + msg.size = 0;
> +
> + err = vhost_user_write(dev, &msg, NULL, 0);
> + if (err < 0) {
> + return err;
> + }
> +
> + err = vhost_user_read(dev, &msg);
> + if (err < 0) {
> + return err;
> + }
> +
> + dev->protocol_features = msg.u64 & VHOST_USER_PROTOCOL_FEATURE_MASK;
> +
> + msg.request = VHOST_USER_SET_PROTOCOL_FEATURES;
> + msg.flags = VHOST_USER_VERSION;
> + msg.u64 = dev->protocol_features;
> + msg.size = sizeof msg.u64;
> +
> + err = vhost_user_write(dev, &msg, NULL, 0);
> + if (err < 0) {
> + return err;
> + }
> + }
> +
> return 0;
> }
>
> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
> index 650bb18..0062baa 100644
> --- a/docs/specs/vhost-user.txt
> +++ b/docs/specs/vhost-user.txt
> @@ -113,6 +113,7 @@ message replies. Most of the requests don't require
> replies. Here is a list of
> the ones that do:
>
> * VHOST_GET_FEATURES
> + * VHOST_GET_PROTOCOL_FEATURES
> * VHOST_GET_VRING_BASE
>
> There are several messages that the master sends with file descriptors passed
> @@ -127,6 +128,13 @@ in the ancillary data:
> If Master is unable to send the full message or receives a wrong reply it
> will
> close the connection. An optional reconnection mechanism can be implemented.
>
> +Any protocol extensions are gated by protocol feature bits,
> +which allows full backwards compatibility on both master
> +and slave.
> +As older slaves don't support negotiating protocol features,
> +a feature bit was dedicated for this purpose:
> +#define VHOST_USER_F_PROTOCOL_FEATURES 30
> +
> Message types
> -------------
>
> @@ -138,6 +146,8 @@ Message types
> Slave payload: u64
>
> Get from the underlying vhost implementation the features bitmask.
> + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for
> + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES.
>
> * VHOST_USER_SET_FEATURES
>
> @@ -146,6 +156,33 @@ Message types
> Master payload: u64
>
> Enable features in the underlying vhost implementation using a bitmask.
> + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals master support for
> + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES.
> +
> + * VHOST_USER_GET_PROTOCOL_FEATURES
> +
> + Id: 15
> + Equivalent ioctl: VHOST_GET_FEATURES
> + Master payload: N/A
> + Slave payload: u64
> +
> + Get the protocol feature bitmask from the underlying vhost
> implementation.
> + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in
> + VHOST_USER_GET_FEATURES.
> + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support
> + this message even before VHOST_USER_SET_FEATURES was called.
> +
> + * VHOST_USER_SET_PROTOCOL_FEATURES
> +
> + Id: 16
> + Ioctl: VHOST_SET_FEATURES
> + Master payload: u64
> +
> + Enable protocol features in the underlying vhost implementation.
> + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in
> + VHOST_USER_GET_FEATURES.
> + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support
> + this message even before VHOST_USER_SET_FEATURES was called.
>
> * VHOST_USER_SET_OWNER
>
> --
> MST
>
- [Qemu-devel] [PATCH 0/4] vhost-user: protocol updates, Michael S. Tsirkin, 2015/07/17
- [Qemu-devel] [PATCH 2/4] vhost-user: refactor ioctl translation, Michael S. Tsirkin, 2015/07/17
- [Qemu-devel] [PATCH 1/4] Revert "vhost-user: add multi queue support", Michael S. Tsirkin, 2015/07/17
- [Qemu-devel] [PATCH 3/4] vhost-user: add protocol feature negotiation, Michael S. Tsirkin, 2015/07/17
- [Qemu-devel] [PATCH 4/4] vhost-user: unit test for new messages, Michael S. Tsirkin, 2015/07/17
- Re: [Qemu-devel] [PATCH 0/4] vhost-user: protocol updates, Maxime Leroy, 2015/07/17
- Re: [Qemu-devel] [PATCH 0/4] vhost-user: protocol updates, Flavio Leitner, 2015/07/17
- Re: [Qemu-devel] [PATCH 0/4] vhost-user: protocol updates, Thibaut Collet, 2015/07/24