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[67.166.91.86]) by smtp.gmail.com with ESMTPSA id v24-20020aa78518000000b00679b7d2bd57sm11605103pfn.192.2023.08.02.17.53.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Aug 2023 17:53:22 -0700 (PDT) Date: Thu, 3 Aug 2023 00:53:22 +0000 From: Bobby Eshleman To: Arseniy Krasnov Cc: Bobby Eshleman , Stefan Hajnoczi , Stefano Garzarella , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Bryan Tan , Vishnu Dasa , VMware PV-Drivers Reviewers , Dan Carpenter , Simon Horman , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH RFC net-next v5 03/14] af_vsock: support multi-transport datagrams Message-ID: References: <20230413-b4-vsock-dgram-v5-0-581bd37fdb26@bytedance.com> <20230413-b4-vsock-dgram-v5-3-581bd37fdb26@bytedance.com> <43fad7ab-2ca9-608e-566f-80e607d2d6b8@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_BLOCKED,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 02, 2023 at 10:24:44PM +0000, Bobby Eshleman wrote: > On Sun, Jul 23, 2023 at 12:53:15AM +0300, Arseniy Krasnov wrote: > > > > > > On 19.07.2023 03:50, Bobby Eshleman wrote: > > > This patch adds support for multi-transport datagrams. > > > > > > This includes: > > > - Per-packet lookup of transports when using sendto(sockaddr_vm) > > > - Selecting H2G or G2H transport using VMADDR_FLAG_TO_HOST and CID in > > > sockaddr_vm > > > - rename VSOCK_TRANSPORT_F_DGRAM to VSOCK_TRANSPORT_F_DGRAM_FALLBACK > > > - connect() now assigns the transport for (similar to connectible > > > sockets) > > > > > > To preserve backwards compatibility with VMCI, some important changes > > > are made. The "transport_dgram" / VSOCK_TRANSPORT_F_DGRAM is changed to > > > be used for dgrams only if there is not yet a g2h or h2g transport that > > > has been registered that can transmit the packet. If there is a g2h/h2g > > > transport for that remote address, then that transport will be used and > > > not "transport_dgram". This essentially makes "transport_dgram" a > > > fallback transport for when h2g/g2h has not yet gone online, and so it > > > is renamed "transport_dgram_fallback". VMCI implements this transport. > > > > > > The logic around "transport_dgram" needs to be retained to prevent > > > breaking VMCI: > > > > > > 1) VMCI datagrams existed prior to h2g/g2h and so operate under a > > > different paradigm. When the vmci transport comes online, it registers > > > itself with the DGRAM feature, but not H2G/G2H. Only later when the > > > transport has more information about its environment does it register > > > H2G or G2H. In the case that a datagram socket is created after > > > VSOCK_TRANSPORT_F_DGRAM registration but before G2H/H2G registration, > > > the "transport_dgram" transport is the only registered transport and so > > > needs to be used. > > > > > > 2) VMCI seems to require a special message be sent by the transport when a > > > datagram socket calls bind(). Under the h2g/g2h model, the transport > > > is selected using the remote_addr which is set by connect(). At > > > bind time there is no remote_addr because often no connect() has been > > > called yet: the transport is null. Therefore, with a null transport > > > there doesn't seem to be any good way for a datagram socket to tell the > > > VMCI transport that it has just had bind() called upon it. > > > > > > With the new fallback logic, after H2G/G2H comes online the socket layer > > > will access the VMCI transport via transport_{h2g,g2h}. Prior to H2G/G2H > > > coming online, the socket layer will access the VMCI transport via > > > "transport_dgram_fallback". > > > > > > Only transports with a special datagram fallback use-case such as VMCI > > > need to register VSOCK_TRANSPORT_F_DGRAM_FALLBACK. > > > > > > Signed-off-by: Bobby Eshleman > > > --- > > > drivers/vhost/vsock.c | 1 - > > > include/linux/virtio_vsock.h | 2 -- > > > include/net/af_vsock.h | 10 +++--- > > > net/vmw_vsock/af_vsock.c | 64 ++++++++++++++++++++++++++------- > > > net/vmw_vsock/hyperv_transport.c | 6 ---- > > > net/vmw_vsock/virtio_transport.c | 1 - > > > net/vmw_vsock/virtio_transport_common.c | 7 ---- > > > net/vmw_vsock/vmci_transport.c | 2 +- > > > net/vmw_vsock/vsock_loopback.c | 1 - > > > 9 files changed, 58 insertions(+), 36 deletions(-) > > > > > > diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c > > > index ae8891598a48..d5d6a3c3f273 100644 > > > --- a/drivers/vhost/vsock.c > > > +++ b/drivers/vhost/vsock.c > > > @@ -410,7 +410,6 @@ static struct virtio_transport vhost_transport = { > > > .cancel_pkt = vhost_transport_cancel_pkt, > > > > > > .dgram_enqueue = virtio_transport_dgram_enqueue, > > > - .dgram_bind = virtio_transport_dgram_bind, > > > .dgram_allow = virtio_transport_dgram_allow, > > > > > > .stream_enqueue = virtio_transport_stream_enqueue, > > > diff --git a/include/linux/virtio_vsock.h b/include/linux/virtio_vsock.h > > > index 18cbe8d37fca..7632552bee58 100644 > > > --- a/include/linux/virtio_vsock.h > > > +++ b/include/linux/virtio_vsock.h > > > @@ -211,8 +211,6 @@ void virtio_transport_notify_buffer_size(struct vsock_sock *vsk, u64 *val); > > > u64 virtio_transport_stream_rcvhiwat(struct vsock_sock *vsk); > > > bool virtio_transport_stream_is_active(struct vsock_sock *vsk); > > > bool virtio_transport_stream_allow(u32 cid, u32 port); > > > -int virtio_transport_dgram_bind(struct vsock_sock *vsk, > > > - struct sockaddr_vm *addr); > > > bool virtio_transport_dgram_allow(u32 cid, u32 port); > > > > > > int virtio_transport_connect(struct vsock_sock *vsk); > > > diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h > > > index 305d57502e89..f6a0ca9d7c3e 100644 > > > --- a/include/net/af_vsock.h > > > +++ b/include/net/af_vsock.h > > > @@ -96,13 +96,13 @@ struct vsock_transport_send_notify_data { > > > > > > /* Transport features flags */ > > > /* Transport provides host->guest communication */ > > > -#define VSOCK_TRANSPORT_F_H2G 0x00000001 > > > +#define VSOCK_TRANSPORT_F_H2G 0x00000001 > > > /* Transport provides guest->host communication */ > > > -#define VSOCK_TRANSPORT_F_G2H 0x00000002 > > > -/* Transport provides DGRAM communication */ > > > -#define VSOCK_TRANSPORT_F_DGRAM 0x00000004 > > > +#define VSOCK_TRANSPORT_F_G2H 0x00000002 > > > +/* Transport provides fallback for DGRAM communication */ > > > +#define VSOCK_TRANSPORT_F_DGRAM_FALLBACK 0x00000004 > > > /* Transport provides local (loopback) communication */ > > > -#define VSOCK_TRANSPORT_F_LOCAL 0x00000008 > > > +#define VSOCK_TRANSPORT_F_LOCAL 0x00000008 > > > > > > struct vsock_transport { > > > struct module *module; > > > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > > > index ae5ac5531d96..26c97b33d55a 100644 > > > --- a/net/vmw_vsock/af_vsock.c > > > +++ b/net/vmw_vsock/af_vsock.c > > > @@ -139,8 +139,8 @@ struct proto vsock_proto = { > > > static const struct vsock_transport *transport_h2g; > > > /* Transport used for guest->host communication */ > > > static const struct vsock_transport *transport_g2h; > > > -/* Transport used for DGRAM communication */ > > > -static const struct vsock_transport *transport_dgram; > > > +/* Transport used as a fallback for DGRAM communication */ > > > +static const struct vsock_transport *transport_dgram_fallback; > > > /* Transport used for local communication */ > > > static const struct vsock_transport *transport_local; > > > static DEFINE_MUTEX(vsock_register_mutex); > > > @@ -439,6 +439,18 @@ vsock_connectible_lookup_transport(unsigned int cid, __u8 flags) > > > return transport; > > > } > > > > > > +static const struct vsock_transport * > > > +vsock_dgram_lookup_transport(unsigned int cid, __u8 flags) > > > +{ > > > + const struct vsock_transport *transport; > > > + > > > + transport = vsock_connectible_lookup_transport(cid, flags); > > > + if (transport) > > > + return transport; > > > + > > > + return transport_dgram_fallback; > > > +} > > > + > > > /* Assign a transport to a socket and call the .init transport callback. > > > * > > > * Note: for connection oriented socket this must be called when vsk->remote_addr > > > @@ -475,7 +487,8 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk) > > > > > > switch (sk->sk_type) { > > > case SOCK_DGRAM: > > > - new_transport = transport_dgram; > > > + new_transport = vsock_dgram_lookup_transport(remote_cid, > > > + remote_flags); > > > > I'm a little bit confused about this: > > 1) Let's create SOCK_DGRAM socket using vsock_create() > > 2) for SOCK_DGRAM it calls 'vsock_assign_transport()' and we go here, remote_cid == -1 > > 3) I guess 'vsock_dgram_lookup_transport()' calls logic from 0002 and returns h2g for such remote cid, which is not > > correct I think... > > > > Please correct me if i'm wrong > > > > Thanks, Arseniy > > > > As I understand, for the VMCI case, if transport_h2g != NULL, then > transport_h2g == transport_dgram_fallback. In either case, > vsk->transport == transport_dgram_fallback. > > For the virtio/vhost case, temporarily vsk->transport == transport_h2g, > but it is unused because vsk->transport->dgram_bind == NULL. > > Until SS_CONNECTED is set by connect() and vsk->transport is set > correctly, the send path is barred from using the bad transport. > > I guess the recvmsg() path is a little more sketchy, and probably only > works in my test cases because h2g/g2h in the vhost/virtio case have > identical dgram_addr_init() implementations. > > I think a cleaner solution is maybe checking in vsock_create() if > dgram_bind is implemented. If it is not, then vsk->transport should be > reset to NULL and a comment added explaining why VMCI requires this. > > Then the other calls can begin explicitly checking for vsk->transport == > NULL. Actually, on further reflection here, in order for the vsk->transport to be called in time for ->dgram_addr_init(), it is going to be necessary to call vsock_assign_transport() in vsock_dgram_bind() anyway. I think this means that the vsock_assign_transport() call can be removed from vsock_create() call entirely, and yet VMCI can still dispatch messages upon bind() calls as needed. This would then simplify the whole arrangement, if there aren't other unseen issues. > > Thoughts? > > > > break; > > > case SOCK_STREAM: > > > case SOCK_SEQPACKET: > > > @@ -692,6 +705,9 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk, > > > static int __vsock_bind_dgram(struct vsock_sock *vsk, > > > struct sockaddr_vm *addr) > > > { > > > + if (!vsk->transport || !vsk->transport->dgram_bind) > > > + return -EINVAL; > > > + > > > return vsk->transport->dgram_bind(vsk, addr); > > > } > > > > > > @@ -1162,6 +1178,7 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg, > > > struct vsock_sock *vsk; > > > struct sockaddr_vm *remote_addr; > > > const struct vsock_transport *transport; > > > + bool module_got = false; > > > > > > if (msg->msg_flags & MSG_OOB) > > > return -EOPNOTSUPP; > > > @@ -1173,19 +1190,34 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg, > > > > > > lock_sock(sk); > > > > > > - transport = vsk->transport; > > > - > > > err = vsock_auto_bind(vsk); > > > if (err) > > > goto out; > > > > > > - > > > /* If the provided message contains an address, use that. Otherwise > > > * fall back on the socket's remote handle (if it has been connected). > > > */ > > > if (msg->msg_name && > > > vsock_addr_cast(msg->msg_name, msg->msg_namelen, > > > &remote_addr) == 0) { > > > + transport = vsock_dgram_lookup_transport(remote_addr->svm_cid, > > > + remote_addr->svm_flags); > > > + if (!transport) { > > > + err = -EINVAL; > > > + goto out; > > > + } > > > + > > > + if (!try_module_get(transport->module)) { > > > + err = -ENODEV; > > > + goto out; > > > + } > > > + > > > + /* When looking up a transport dynamically and acquiring a > > > + * reference on the module, we need to remember to release the > > > + * reference later. > > > + */ > > > + module_got = true; > > > + > > > /* Ensure this address is of the right type and is a valid > > > * destination. > > > */ > > > @@ -1200,6 +1232,7 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg, > > > } else if (sock->state == SS_CONNECTED) { > > > remote_addr = &vsk->remote_addr; > > > > > > + transport = vsk->transport; > > > if (remote_addr->svm_cid == VMADDR_CID_ANY) > > > remote_addr->svm_cid = transport->get_local_cid(); > > > > > > @@ -1224,6 +1257,8 @@ static int vsock_dgram_sendmsg(struct socket *sock, struct msghdr *msg, > > > err = transport->dgram_enqueue(vsk, remote_addr, msg, len); > > > > > > out: > > > + if (module_got) > > > + module_put(transport->module); > > > release_sock(sk); > > > return err; > > > } > > > @@ -1256,13 +1291,18 @@ static int vsock_dgram_connect(struct socket *sock, > > > if (err) > > > goto out; > > > > > > + memcpy(&vsk->remote_addr, remote_addr, sizeof(vsk->remote_addr)); > > > + > > > + err = vsock_assign_transport(vsk, NULL); > > > + if (err) > > > + goto out; > > > + > > > if (!vsk->transport->dgram_allow(remote_addr->svm_cid, > > > remote_addr->svm_port)) { > > > err = -EINVAL; > > > goto out; > > > } > > > > > > - memcpy(&vsk->remote_addr, remote_addr, sizeof(vsk->remote_addr)); > > > sock->state = SS_CONNECTED; > > > > > > /* sock map disallows redirection of non-TCP sockets with sk_state != > > > @@ -2487,7 +2527,7 @@ int vsock_core_register(const struct vsock_transport *t, int features) > > > > > > t_h2g = transport_h2g; > > > t_g2h = transport_g2h; > > > - t_dgram = transport_dgram; > > > + t_dgram = transport_dgram_fallback; > > > t_local = transport_local; > > > > > > if (features & VSOCK_TRANSPORT_F_H2G) { > > > @@ -2506,7 +2546,7 @@ int vsock_core_register(const struct vsock_transport *t, int features) > > > t_g2h = t; > > > } > > > > > > - if (features & VSOCK_TRANSPORT_F_DGRAM) { > > > + if (features & VSOCK_TRANSPORT_F_DGRAM_FALLBACK) { > > > if (t_dgram) { > > > err = -EBUSY; > > > goto err_busy; > > > @@ -2524,7 +2564,7 @@ int vsock_core_register(const struct vsock_transport *t, int features) > > > > > > transport_h2g = t_h2g; > > > transport_g2h = t_g2h; > > > - transport_dgram = t_dgram; > > > + transport_dgram_fallback = t_dgram; > > > transport_local = t_local; > > > > > > err_busy: > > > @@ -2543,8 +2583,8 @@ void vsock_core_unregister(const struct vsock_transport *t) > > > if (transport_g2h == t) > > > transport_g2h = NULL; > > > > > > - if (transport_dgram == t) > > > - transport_dgram = NULL; > > > + if (transport_dgram_fallback == t) > > > + transport_dgram_fallback = NULL; > > > > > > if (transport_local == t) > > > transport_local = NULL; > > > diff --git a/net/vmw_vsock/hyperv_transport.c b/net/vmw_vsock/hyperv_transport.c > > > index 7f1ea434656d..c29000f2612a 100644 > > > --- a/net/vmw_vsock/hyperv_transport.c > > > +++ b/net/vmw_vsock/hyperv_transport.c > > > @@ -551,11 +551,6 @@ static void hvs_destruct(struct vsock_sock *vsk) > > > kfree(hvs); > > > } > > > > > > -static int hvs_dgram_bind(struct vsock_sock *vsk, struct sockaddr_vm *addr) > > > -{ > > > - return -EOPNOTSUPP; > > > -} > > > - > > > static int hvs_dgram_enqueue(struct vsock_sock *vsk, > > > struct sockaddr_vm *remote, struct msghdr *msg, > > > size_t dgram_len) > > > @@ -826,7 +821,6 @@ static struct vsock_transport hvs_transport = { > > > .connect = hvs_connect, > > > .shutdown = hvs_shutdown, > > > > > > - .dgram_bind = hvs_dgram_bind, > > > .dgram_enqueue = hvs_dgram_enqueue, > > > .dgram_allow = hvs_dgram_allow, > > > > > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > > > index 66edffdbf303..ac2126c7dac5 100644 > > > --- a/net/vmw_vsock/virtio_transport.c > > > +++ b/net/vmw_vsock/virtio_transport.c > > > @@ -428,7 +428,6 @@ static struct virtio_transport virtio_transport = { > > > .shutdown = virtio_transport_shutdown, > > > .cancel_pkt = virtio_transport_cancel_pkt, > > > > > > - .dgram_bind = virtio_transport_dgram_bind, > > > .dgram_enqueue = virtio_transport_dgram_enqueue, > > > .dgram_allow = virtio_transport_dgram_allow, > > > > > > diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c > > > index 01ea1402ad40..ffcbdd77feaa 100644 > > > --- a/net/vmw_vsock/virtio_transport_common.c > > > +++ b/net/vmw_vsock/virtio_transport_common.c > > > @@ -781,13 +781,6 @@ bool virtio_transport_stream_allow(u32 cid, u32 port) > > > } > > > EXPORT_SYMBOL_GPL(virtio_transport_stream_allow); > > > > > > -int virtio_transport_dgram_bind(struct vsock_sock *vsk, > > > - struct sockaddr_vm *addr) > > > -{ > > > - return -EOPNOTSUPP; > > > -} > > > -EXPORT_SYMBOL_GPL(virtio_transport_dgram_bind); > > > - > > > bool virtio_transport_dgram_allow(u32 cid, u32 port) > > > { > > > return false; > > > diff --git a/net/vmw_vsock/vmci_transport.c b/net/vmw_vsock/vmci_transport.c > > > index 0bbbdb222245..857b0461f856 100644 > > > --- a/net/vmw_vsock/vmci_transport.c > > > +++ b/net/vmw_vsock/vmci_transport.c > > > @@ -2072,7 +2072,7 @@ static int __init vmci_transport_init(void) > > > /* Register only with dgram feature, other features (H2G, G2H) will be > > > * registered when the first host or guest becomes active. > > > */ > > > - err = vsock_core_register(&vmci_transport, VSOCK_TRANSPORT_F_DGRAM); > > > + err = vsock_core_register(&vmci_transport, VSOCK_TRANSPORT_F_DGRAM_FALLBACK); > > > if (err < 0) > > > goto err_unsubscribe; > > > > > > diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c > > > index 2a59dd177c74..278235ea06c4 100644 > > > --- a/net/vmw_vsock/vsock_loopback.c > > > +++ b/net/vmw_vsock/vsock_loopback.c > > > @@ -61,7 +61,6 @@ static struct virtio_transport loopback_transport = { > > > .shutdown = virtio_transport_shutdown, > > > .cancel_pkt = vsock_loopback_cancel_pkt, > > > > > > - .dgram_bind = virtio_transport_dgram_bind, > > > .dgram_enqueue = virtio_transport_dgram_enqueue, > > > .dgram_allow = virtio_transport_dgram_allow, > > > > > >