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[Qemu-devel] [PATCH 3/4] vhost-user: add protocol feature negotiation
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PATCH 3/4] vhost-user: add protocol feature negotiation |
Date: |
Fri, 17 Jul 2015 17:09:38 +0300 |
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,
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 <=
- [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