On Fri, May 26, 2017 at 04:28:57PM +0200, Maxime Coquelin wrote: > From: Marc-André Lureau <marcandre.lur...@redhat.com> > > Learn to give a socket to the slave to let him make requests to the > master. > > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> > Signed-off-by: Maxime Coquelin <maxime.coque...@redhat.com> > --- > docs/specs/vhost-user.txt | 32 +++++++++++- > hw/virtio/vhost-user.c | 127 > ++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 157 insertions(+), 2 deletions(-) > > diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt > index 036890f..5fa7016 100644 > --- a/docs/specs/vhost-user.txt > +++ b/docs/specs/vhost-user.txt > @@ -139,6 +139,7 @@ in the ancillary data: > * VHOST_USER_SET_VRING_KICK > * VHOST_USER_SET_VRING_CALL > * VHOST_USER_SET_VRING_ERR > + * VHOST_USER_SET_SLAVE_REQ_FD > > 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. > @@ -252,6 +253,18 @@ Once the source has finished migration, rings will be > stopped by > the source. No further update must be done before rings are > restarted. > > +Slave communication > +------------------- > + > +An optional communication channel is provided if the slave declares > +VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make > +requests to the master. > + > +The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data. > + > +A slave may then send VHOST_USER_SLAVE_* messages to the master > +using this fd communication channel. > + > Protocol features > ----------------- > > @@ -260,9 +273,10 @@ Protocol features > #define VHOST_USER_PROTOCOL_F_RARP 2 > #define VHOST_USER_PROTOCOL_F_REPLY_ACK 3 > #define VHOST_USER_PROTOCOL_F_MTU 4 > +#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5 > > -Message types > -------------- > +Master message types > +-------------------- > > * VHOST_USER_GET_FEATURES >
So down the road, we should make sure a device without VHOST_USER_PROTOCOL_F_SLAVE_REQ does not advertise IOMMU since you don't handle these messages otherwise. > @@ -486,6 +500,20 @@ Message types > If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond > with zero in case the specified MTU is valid, or non-zero otherwise. > > + * VHOST_USER_SET_SLAVE_REQ_FD > + > + Id: 21 > + Equivalent ioctl: N/A > + Master payload: N/A > + > + Set the socket file descriptor for slave initiated requests. It is > passed > + in the ancillary data. > + This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES > + has been negotiated, and protocol feature bit > VHOST_USER_PROTOCOL_F_SLAVE_REQ > + bit is present in VHOST_USER_GET_PROTOCOL_FEATURES. > + If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond > + with zero for success, non-zero otherwise. > + > VHOST_USER_PROTOCOL_F_REPLY_ACK: > ------------------------------- > The original vhost-user specification only demands replies for certain > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > index 8a602e0..ea988fe 100644 > --- a/hw/virtio/vhost-user.c > +++ b/hw/virtio/vhost-user.c > @@ -32,6 +32,7 @@ enum VhostUserProtocolFeature { > VHOST_USER_PROTOCOL_F_RARP = 2, > VHOST_USER_PROTOCOL_F_REPLY_ACK = 3, > VHOST_USER_PROTOCOL_F_NET_MTU = 4, > + VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5, > > VHOST_USER_PROTOCOL_F_MAX > }; > @@ -60,9 +61,15 @@ typedef enum VhostUserRequest { > VHOST_USER_SET_VRING_ENABLE = 18, > VHOST_USER_SEND_RARP = 19, > VHOST_USER_NET_SET_MTU = 20, > + VHOST_USER_SET_SLAVE_REQ_FD = 21, > VHOST_USER_MAX > } VhostUserRequest; > > +typedef enum VhostUserSlaveRequest { > + VHOST_USER_SLAVE_NONE = 0, > + VHOST_USER_SLAVE_MAX > +} VhostUserSlaveRequest; > + > typedef struct VhostUserMemoryRegion { > uint64_t guest_phys_addr; > uint64_t memory_size; > @@ -112,6 +119,7 @@ static VhostUserMsg m __attribute__ ((unused)); > > struct vhost_user { > CharBackend *chr; > + int slave_fd; > }; > > static bool ioeventfd_enabled(void) > @@ -578,6 +586,115 @@ static int vhost_user_reset_device(struct vhost_dev > *dev) > return 0; > } > > +static void slave_read(void *opaque) > +{ > + struct vhost_dev *dev = opaque; > + struct vhost_user *u = dev->opaque; > + VhostUserMsg msg = { 0, }; > + int size, ret = 0; > + > + /* Read header */ > + size = read(u->slave_fd, &msg, VHOST_USER_HDR_SIZE); > + if (size != VHOST_USER_HDR_SIZE) { > + error_report("Failed to read from slave."); > + goto err; > + } > + > + if (msg.size > VHOST_USER_PAYLOAD_SIZE) { > + error_report("Failed to read msg header." > + " Size %d exceeds the maximum %zu.", msg.size, > + VHOST_USER_PAYLOAD_SIZE); > + goto err; > + } > + > + /* Read payload */ > + size = read(u->slave_fd, &msg.payload, msg.size); > + if (size != msg.size) { > + error_report("Failed to read payload from slave."); > + goto err; > + } > + > + switch (msg.request) { > + default: > + error_report("Received unexpected msg type."); > + ret = -EINVAL; > + } > + > + /* > + * REPLY_ACK feature handling. Other reply types has to be managed > + * directly in their request handlers. > + */ > + if (msg.flags & VHOST_USER_NEED_REPLY_MASK) { > + msg.flags &= ~VHOST_USER_NEED_REPLY_MASK; > + msg.flags |= VHOST_USER_REPLY_MASK; > + > + msg.payload.u64 = !!ret; > + msg.size = sizeof(msg.payload.u64); > + > + size = write(u->slave_fd, &msg, VHOST_USER_HDR_SIZE + msg.size); > + if (size != VHOST_USER_HDR_SIZE + msg.size) { > + error_report("Failed to send msg reply to slave."); > + goto err; > + } > + } > + > + return; > + > +err: > + qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL); > + close(u->slave_fd); > + u->slave_fd = -1; > + return; > +} > + > +static int vhost_setup_slave_channel(struct vhost_dev *dev) > +{ > + VhostUserMsg msg = { > + .request = VHOST_USER_SET_SLAVE_REQ_FD, > + .flags = VHOST_USER_VERSION, > + }; > + struct vhost_user *u = dev->opaque; > + int sv[2], ret = 0; > + bool reply_supported = virtio_has_feature(dev->protocol_features, > + > VHOST_USER_PROTOCOL_F_REPLY_ACK); > + > + if (!virtio_has_feature(dev->protocol_features, > + VHOST_USER_PROTOCOL_F_SLAVE_REQ)) { > + return 0; > + } > + > + if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) { > + error_report("socketpair() failed"); > + return -1; > + } > + > + u->slave_fd = sv[0]; > + qemu_set_fd_handler(u->slave_fd, slave_read, NULL, dev); > + > + if (reply_supported) { > + msg.flags |= VHOST_USER_NEED_REPLY_MASK; > + } > + > + ret = vhost_user_write(dev, &msg, &sv[1], 1); > + if (ret) { > + goto out; > + } > + > + if (reply_supported) { > + ret = process_message_reply(dev, msg); > + } > + > +out: > + close(sv[1]); > + if (ret) { > + qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL); > + close(u->slave_fd); > + u->slave_fd = -1; > + } > + > + return ret; > +} > + > static int vhost_user_init(struct vhost_dev *dev, void *opaque) > { > uint64_t features; > @@ -588,6 +705,7 @@ static int vhost_user_init(struct vhost_dev *dev, void > *opaque) > > u = g_new0(struct vhost_user, 1); > u->chr = opaque; > + u->slave_fd = -1; > dev->opaque = u; > > err = vhost_user_get_features(dev, &features); > @@ -628,6 +746,11 @@ static int vhost_user_init(struct vhost_dev *dev, void > *opaque) > "VHOST_USER_PROTOCOL_F_LOG_SHMFD feature."); > } > > + err = vhost_setup_slave_channel(dev); > + if (err < 0) { > + return err; > + } > + > return 0; > } > > @@ -638,6 +761,10 @@ static int vhost_user_cleanup(struct vhost_dev *dev) > assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER); > > u = dev->opaque; > + if (u->slave_fd >= 0) { > + close(u->slave_fd); > + u->slave_fd = -1; > + } > g_free(u); > dev->opaque = 0; > > -- > 2.9.4