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Date:   Thu, 22 Jun 2023 23:16:49 +0000
From:   Bobby Eshleman <bobbyeshleman@gmail.com>
To:     Arseniy Krasnov <oxffffaa@gmail.com>
Cc:     Bobby Eshleman <bobby.eshleman@bytedance.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
        Bryan Tan <bryantan@vmware.com>,
        Vishnu Dasa <vdasa@vmware.com>,
        VMware PV-Drivers Reviewers <pv-drivers@vmware.com>,
        Dan Carpenter <dan.carpenter@linaro.org>,
        Simon Horman <simon.horman@corigine.com>, 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, Jiang Wang <jiang.wang@bytedance.com>
Subject: Re: [PATCH RFC net-next v4 8/8] tests: add vsock dgram tests
Message-ID: <ZJTWYRGd95xl+yRE@bullseye>
References: <20230413-b4-vsock-dgram-v4-0-0cebbb2ae899@bytedance.com>
 <20230413-b4-vsock-dgram-v4-8-0cebbb2ae899@bytedance.com>
 <484c7b6f-5ce5-ce43-2dfd-0ae3063f1e47@gmail.com>
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In-Reply-To: <484c7b6f-5ce5-ce43-2dfd-0ae3063f1e47@gmail.com>
Precedence: bulk

On Sun, Jun 11, 2023 at 11:54:57PM +0300, Arseniy Krasnov wrote:
> Hello Bobby!
> 
> Sorry, may be I become a little bit annoying:), but I tried to run vsock_test with
> this v4 version, and again get the same crash:

Haha not annoying at all. I appreciate the testing!

> 
> # cat client.sh 
> ./vsock_test  --mode=client --control-host=192.168.1.1 --control-port=12345 --peer-cid=2
> # ./client.sh 
> Control socket connected to 192.168.1.1:12345.
> 0 - SOCK_STREAM connection reset...[   20.065237] BUG: kernel NULL pointer dereference, addre0
> [   20.065895] #PF: supervisor read access in kernel mode
> [   20.065895] #PF: error_code(0x0000) - not-present page
> [   20.065895] PGD 0 P4D 0 
> [   20.065895] Oops: 0000 [#1] PREEMPT SMP PTI
> [   20.065895] CPU: 0 PID: 111 Comm: vsock_test Not tainted 6.4.0-rc3-gefcccba07069 #385
> [   20.065895] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd44
> [   20.065895] RIP: 0010:static_key_count+0x0/0x20
> [   20.065895] Code: 04 4c 8b 46 08 49 29 c0 4c 01 c8 4c 89 47 08 89 0e 89 56 04 48 89 46 08 f
> [   20.065895] RSP: 0018:ffffbbb000223dc0 EFLAGS: 00010202
> [   20.065895] RAX: ffffffff85709880 RBX: ffffffffc0079140 RCX: 0000000000000000
> [   20.065895] RDX: ffff9f73c2175700 RSI: 0000000000000000 RDI: 0000000000000000
> [   20.065895] RBP: ffff9f73c2385900 R08: ffffbbb000223d30 R09: ffff9f73ff896000
> [   20.065895] R10: 0000000000001000 R11: 0000000000000000 R12: ffffbbb000223e80
> [   20.065895] R13: 0000000000000000 R14: 0000000000000002 R15: ffff9f73c1cfaa80
> [   20.065895] FS:  00007f1ad82f55c0(0000) GS:ffff9f73fe400000(0000) knlGS:0000000000000000
> [   20.065895] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   20.065895] CR2: 0000000000000000 CR3: 000000003f954000 CR4: 00000000000006f0
> [   20.065895] Call Trace:
> [   20.065895]  <TASK>
> [   20.065895]  once_deferred+0xd/0x30
> [   20.065895]  vsock_assign_transport+0x9a/0x1b0 [vsock]
> [   20.065895]  vsock_connect+0xb4/0x3a0 [vsock]
> [   20.065895]  ? var_wake_function+0x60/0x60
> [   20.065895]  __sys_connect+0x9e/0xd0
> [   20.065895]  ? _raw_spin_unlock_irq+0xe/0x30
> [   20.065895]  ? do_setitimer+0x128/0x1f0
> [   20.065895]  ? alarm_setitimer+0x4c/0x90
> [   20.065895]  ? fpregs_assert_state_consistent+0x1d/0x50
> [   20.065895]  ? exit_to_user_mode_prepare+0x36/0x130
> [   20.065895]  __x64_sys_connect+0x11/0x20
> [   20.065895]  do_syscall_64+0x3b/0xc0
> [   20.065895]  entry_SYSCALL_64_after_hwframe+0x4b/0xb5
> [   20.065895] RIP: 0033:0x7f1ad822dd13
> [   20.065895] Code: 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 64 8
> [   20.065895] RSP: 002b:00007ffc513e3c98 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
> [   20.065895] RAX: ffffffffffffffda RBX: 000055aed298e020 RCX: 00007f1ad822dd13
> [   20.065895] RDX: 0000000000000010 RSI: 00007ffc513e3cb0 RDI: 0000000000000004
> [   20.065895] RBP: 0000000000000004 R08: 000055aed32b2018 R09: 0000000000000000
> [   20.065895] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> [   20.065895] R13: 000055aed298acb1 R14: 00007ffc513e3cb0 R15: 00007ffc513e3d40
> [   20.065895]  </TASK>
> [   20.065895] Modules linked in: vsock_loopback vhost_vsock vmw_vsock_virtio_transport vmw_vb

^ I'm guessing this is the difference between our setups. I have been
going all built-in, let me see if I can reproduce w/ modules...

> [   20.065895] CR2: 0000000000000000
> [   20.154060] ---[ end trace 0000000000000000 ]---
> [   20.155519] RIP: 0010:static_key_count+0x0/0x20
> [   20.156932] Code: 04 4c 8b 46 08 49 29 c0 4c 01 c8 4c 89 47 08 89 0e 89 56 04 48 89 46 08 f
> [   20.161367] RSP: 0018:ffffbbb000223dc0 EFLAGS: 00010202
> [   20.162613] RAX: ffffffff85709880 RBX: ffffffffc0079140 RCX: 0000000000000000
> [   20.164262] RDX: ffff9f73c2175700 RSI: 0000000000000000 RDI: 0000000000000000
> [   20.165934] RBP: ffff9f73c2385900 R08: ffffbbb000223d30 R09: ffff9f73ff896000
> [   20.167684] R10: 0000000000001000 R11: 0000000000000000 R12: ffffbbb000223e80
> [   20.169427] R13: 0000000000000000 R14: 0000000000000002 R15: ffff9f73c1cfaa80
> [   20.171109] FS:  00007f1ad82f55c0(0000) GS:ffff9f73fe400000(0000) knlGS:0000000000000000
> [   20.173000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   20.174381] CR2: 0000000000000000 CR3: 000000003f954000 CR4: 00000000000006f0
> 
> So, what HEAD do You use? May be You have some specific config (I use x86-64 defconfig + vsock/vhost
> related things) ?
> 

For this series I used net-next:
	28cfea989d6f55c3d10608eba2a2bae609c5bf3e

> Thanks, Arseniy
> 

As always, thanks for the bug finding! I'll report back when I
reproduce or with questions if I can't.

Best,
Bobby

> 
> On 10.06.2023 03:58, Bobby Eshleman wrote:
> > From: Jiang Wang <jiang.wang@bytedance.com>
> > 
> > This patch adds tests for vsock datagram.
> > 
> > Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
> > Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
> > ---
> >  tools/testing/vsock/util.c       | 141 ++++++++++++-
> >  tools/testing/vsock/util.h       |   6 +
> >  tools/testing/vsock/vsock_test.c | 432 +++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 578 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/testing/vsock/util.c b/tools/testing/vsock/util.c
> > index 01b636d3039a..811e70d7cf1e 100644
> > --- a/tools/testing/vsock/util.c
> > +++ b/tools/testing/vsock/util.c
> > @@ -99,7 +99,8 @@ static int vsock_connect(unsigned int cid, unsigned int port, int type)
> >  	int ret;
> >  	int fd;
> >  
> > -	control_expectln("LISTENING");
> > +	if (type != SOCK_DGRAM)
> > +		control_expectln("LISTENING");
> >  
> >  	fd = socket(AF_VSOCK, type, 0);
> >  
> > @@ -130,6 +131,11 @@ int vsock_seqpacket_connect(unsigned int cid, unsigned int port)
> >  	return vsock_connect(cid, port, SOCK_SEQPACKET);
> >  }
> >  
> > +int vsock_dgram_connect(unsigned int cid, unsigned int port)
> > +{
> > +	return vsock_connect(cid, port, SOCK_DGRAM);
> > +}
> > +
> >  /* Listen on <cid, port> and return the first incoming connection.  The remote
> >   * address is stored to clientaddrp.  clientaddrp may be NULL.
> >   */
> > @@ -211,6 +217,34 @@ int vsock_seqpacket_accept(unsigned int cid, unsigned int port,
> >  	return vsock_accept(cid, port, clientaddrp, SOCK_SEQPACKET);
> >  }
> >  
> > +int vsock_dgram_bind(unsigned int cid, unsigned int port)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = port,
> > +			.svm_cid = cid,
> > +		},
> > +	};
> > +	int fd;
> > +
> > +	fd = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +	if (fd < 0) {
> > +		perror("socket");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	if (bind(fd, &addr.sa, sizeof(addr.svm)) < 0) {
> > +		perror("bind");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	return fd;
> > +}
> > +
> >  /* Transmit one byte and check the return value.
> >   *
> >   * expected_ret:
> > @@ -260,6 +294,57 @@ void send_byte(int fd, int expected_ret, int flags)
> >  	}
> >  }
> >  
> > +/* Transmit one byte and check the return value.
> > + *
> > + * expected_ret:
> > + *  <0 Negative errno (for testing errors)
> > + *   0 End-of-file
> > + *   1 Success
> > + */
> > +void sendto_byte(int fd, const struct sockaddr *dest_addr, int len, int expected_ret,
> > +		 int flags)
> > +{
> > +	const uint8_t byte = 'A';
> > +	ssize_t nwritten;
> > +
> > +	timeout_begin(TIMEOUT);
> > +	do {
> > +		nwritten = sendto(fd, &byte, sizeof(byte), flags, dest_addr,
> > +				  len);
> > +		timeout_check("write");
> > +	} while (nwritten < 0 && errno == EINTR);
> > +	timeout_end();
> > +
> > +	if (expected_ret < 0) {
> > +		if (nwritten != -1) {
> > +			fprintf(stderr, "bogus sendto(2) return value %zd\n",
> > +				nwritten);
> > +			exit(EXIT_FAILURE);
> > +		}
> > +		if (errno != -expected_ret) {
> > +			perror("write");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +		return;
> > +	}
> > +
> > +	if (nwritten < 0) {
> > +		perror("write");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +	if (nwritten == 0) {
> > +		if (expected_ret == 0)
> > +			return;
> > +
> > +		fprintf(stderr, "unexpected EOF while sending byte\n");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +	if (nwritten != sizeof(byte)) {
> > +		fprintf(stderr, "bogus sendto(2) return value %zd\n", nwritten);
> > +		exit(EXIT_FAILURE);
> > +	}
> > +}
> > +
> >  /* Receive one byte and check the return value.
> >   *
> >   * expected_ret:
> > @@ -313,6 +398,60 @@ void recv_byte(int fd, int expected_ret, int flags)
> >  	}
> >  }
> >  
> > +/* Receive one byte and check the return value.
> > + *
> > + * expected_ret:
> > + *  <0 Negative errno (for testing errors)
> > + *   0 End-of-file
> > + *   1 Success
> > + */
> > +void recvfrom_byte(int fd, struct sockaddr *src_addr, socklen_t *addrlen,
> > +		   int expected_ret, int flags)
> > +{
> > +	uint8_t byte;
> > +	ssize_t nread;
> > +
> > +	timeout_begin(TIMEOUT);
> > +	do {
> > +		nread = recvfrom(fd, &byte, sizeof(byte), flags, src_addr, addrlen);
> > +		timeout_check("read");
> > +	} while (nread < 0 && errno == EINTR);
> > +	timeout_end();
> > +
> > +	if (expected_ret < 0) {
> > +		if (nread != -1) {
> > +			fprintf(stderr, "bogus recvfrom(2) return value %zd\n",
> > +				nread);
> > +			exit(EXIT_FAILURE);
> > +		}
> > +		if (errno != -expected_ret) {
> > +			perror("read");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +		return;
> > +	}
> > +
> > +	if (nread < 0) {
> > +		perror("read");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +	if (nread == 0) {
> > +		if (expected_ret == 0)
> > +			return;
> > +
> > +		fprintf(stderr, "unexpected EOF while receiving byte\n");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +	if (nread != sizeof(byte)) {
> > +		fprintf(stderr, "bogus recvfrom(2) return value %zd\n", nread);
> > +		exit(EXIT_FAILURE);
> > +	}
> > +	if (byte != 'A') {
> > +		fprintf(stderr, "unexpected byte read %c\n", byte);
> > +		exit(EXIT_FAILURE);
> > +	}
> > +}
> > +
> >  /* Run test cases.  The program terminates if a failure occurs. */
> >  void run_tests(const struct test_case *test_cases,
> >  	       const struct test_opts *opts)
> > diff --git a/tools/testing/vsock/util.h b/tools/testing/vsock/util.h
> > index fb99208a95ea..a69e128d120c 100644
> > --- a/tools/testing/vsock/util.h
> > +++ b/tools/testing/vsock/util.h
> > @@ -37,13 +37,19 @@ void init_signals(void);
> >  unsigned int parse_cid(const char *str);
> >  int vsock_stream_connect(unsigned int cid, unsigned int port);
> >  int vsock_seqpacket_connect(unsigned int cid, unsigned int port);
> > +int vsock_dgram_connect(unsigned int cid, unsigned int port);
> >  int vsock_stream_accept(unsigned int cid, unsigned int port,
> >  			struct sockaddr_vm *clientaddrp);
> >  int vsock_seqpacket_accept(unsigned int cid, unsigned int port,
> >  			   struct sockaddr_vm *clientaddrp);
> > +int vsock_dgram_bind(unsigned int cid, unsigned int port);
> >  void vsock_wait_remote_close(int fd);
> >  void send_byte(int fd, int expected_ret, int flags);
> > +void sendto_byte(int fd, const struct sockaddr *dest_addr, int len, int expected_ret,
> > +		 int flags);
> >  void recv_byte(int fd, int expected_ret, int flags);
> > +void recvfrom_byte(int fd, struct sockaddr *src_addr, socklen_t *addrlen,
> > +		   int expected_ret, int flags);
> >  void run_tests(const struct test_case *test_cases,
> >  	       const struct test_opts *opts);
> >  void list_tests(const struct test_case *test_cases);
> > diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
> > index ac1bd3ac1533..ded82d39ee5d 100644
> > --- a/tools/testing/vsock/vsock_test.c
> > +++ b/tools/testing/vsock/vsock_test.c
> > @@ -1053,6 +1053,413 @@ static void test_stream_virtio_skb_merge_server(const struct test_opts *opts)
> >  	close(fd);
> >  }
> >  
> > +static void test_dgram_sendto_client(const struct test_opts *opts)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = 1234,
> > +			.svm_cid = opts->peer_cid,
> > +		},
> > +	};
> > +	int fd;
> > +
> > +	/* Wait for the server to be ready */
> > +	control_expectln("BIND");
> > +
> > +	fd = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +	if (fd < 0) {
> > +		perror("socket");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	sendto_byte(fd, &addr.sa, sizeof(addr.svm), 1, 0);
> > +
> > +	/* Notify the server that the client has finished */
> > +	control_writeln("DONE");
> > +
> > +	close(fd);
> > +}
> > +
> > +static void test_dgram_sendto_server(const struct test_opts *opts)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = 1234,
> > +			.svm_cid = VMADDR_CID_ANY,
> > +		},
> > +	};
> > +	int len = sizeof(addr.sa);
> > +	int fd;
> > +
> > +	fd = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +	if (fd < 0) {
> > +		perror("socket");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	if (bind(fd, &addr.sa, sizeof(addr.svm)) < 0) {
> > +		perror("bind");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Notify the client that the server is ready */
> > +	control_writeln("BIND");
> > +
> > +	recvfrom_byte(fd, &addr.sa, &len, 1, 0);
> > +
> > +	/* Wait for the client to finish */
> > +	control_expectln("DONE");
> > +
> > +	close(fd);
> > +}
> > +
> > +static void test_dgram_connect_client(const struct test_opts *opts)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = 1234,
> > +			.svm_cid = opts->peer_cid,
> > +		},
> > +	};
> > +	int ret;
> > +	int fd;
> > +
> > +	/* Wait for the server to be ready */
> > +	control_expectln("BIND");
> > +
> > +	fd = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +	if (fd < 0) {
> > +		perror("bind");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	ret = connect(fd, &addr.sa, sizeof(addr.svm));
> > +	if (ret < 0) {
> > +		perror("connect");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	send_byte(fd, 1, 0);
> > +
> > +	/* Notify the server that the client has finished */
> > +	control_writeln("DONE");
> > +
> > +	close(fd);
> > +}
> > +
> > +static void test_dgram_connect_server(const struct test_opts *opts)
> > +{
> > +	test_dgram_sendto_server(opts);
> > +}
> > +
> > +static void test_dgram_multiconn_sendto_client(const struct test_opts *opts)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = 1234,
> > +			.svm_cid = opts->peer_cid,
> > +		},
> > +	};
> > +	int fds[MULTICONN_NFDS];
> > +	int i;
> > +
> > +	/* Wait for the server to be ready */
> > +	control_expectln("BIND");
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++) {
> > +		fds[i] = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +		if (fds[i] < 0) {
> > +			perror("socket");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +	}
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++)
> > +		sendto_byte(fds[i], &addr.sa, sizeof(addr.svm), 1, 0);
> > +
> > +	/* Notify the server that the client has finished */
> > +	control_writeln("DONE");
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++)
> > +		close(fds[i]);
> > +}
> > +
> > +static void test_dgram_multiconn_sendto_server(const struct test_opts *opts)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = 1234,
> > +			.svm_cid = VMADDR_CID_ANY,
> > +		},
> > +	};
> > +	int len = sizeof(addr.sa);
> > +	int fd;
> > +	int i;
> > +
> > +	fd = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +	if (fd < 0) {
> > +		perror("socket");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	if (bind(fd, &addr.sa, sizeof(addr.svm)) < 0) {
> > +		perror("bind");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Notify the client that the server is ready */
> > +	control_writeln("BIND");
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++)
> > +		recvfrom_byte(fd, &addr.sa, &len, 1, 0);
> > +
> > +	/* Wait for the client to finish */
> > +	control_expectln("DONE");
> > +
> > +	close(fd);
> > +}
> > +
> > +static void test_dgram_multiconn_send_client(const struct test_opts *opts)
> > +{
> > +	int fds[MULTICONN_NFDS];
> > +	int i;
> > +
> > +	/* Wait for the server to be ready */
> > +	control_expectln("BIND");
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++) {
> > +		fds[i] = vsock_dgram_connect(opts->peer_cid, 1234);
> > +		if (fds[i] < 0) {
> > +			perror("socket");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +	}
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++)
> > +		send_byte(fds[i], 1, 0);
> > +
> > +	/* Notify the server that the client has finished */
> > +	control_writeln("DONE");
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++)
> > +		close(fds[i]);
> > +}
> > +
> > +static void test_dgram_multiconn_send_server(const struct test_opts *opts)
> > +{
> > +	union {
> > +		struct sockaddr sa;
> > +		struct sockaddr_vm svm;
> > +	} addr = {
> > +		.svm = {
> > +			.svm_family = AF_VSOCK,
> > +			.svm_port = 1234,
> > +			.svm_cid = VMADDR_CID_ANY,
> > +		},
> > +	};
> > +	int fd;
> > +	int i;
> > +
> > +	fd = socket(AF_VSOCK, SOCK_DGRAM, 0);
> > +	if (fd < 0) {
> > +		perror("socket");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	if (bind(fd, &addr.sa, sizeof(addr.svm)) < 0) {
> > +		perror("bind");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Notify the client that the server is ready */
> > +	control_writeln("BIND");
> > +
> > +	for (i = 0; i < MULTICONN_NFDS; i++)
> > +		recv_byte(fd, 1, 0);
> > +
> > +	/* Wait for the client to finish */
> > +	control_expectln("DONE");
> > +
> > +	close(fd);
> > +}
> > +
> > +static void test_dgram_msg_bounds_client(const struct test_opts *opts)
> > +{
> > +	unsigned long recv_buf_size;
> > +	int page_size;
> > +	int msg_cnt;
> > +	int fd;
> > +
> > +	fd = vsock_dgram_connect(opts->peer_cid, 1234);
> > +	if (fd < 0) {
> > +		perror("connect");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Let the server know the client is ready */
> > +	control_writeln("CLNTREADY");
> > +
> > +	msg_cnt = control_readulong();
> > +	recv_buf_size = control_readulong();
> > +
> > +	/* Wait, until receiver sets buffer size. */
> > +	control_expectln("SRVREADY");
> > +
> > +	page_size = getpagesize();
> > +
> > +	for (int i = 0; i < msg_cnt; i++) {
> > +		unsigned long curr_hash;
> > +		ssize_t send_size;
> > +		size_t buf_size;
> > +		void *buf;
> > +
> > +		/* Use "small" buffers and "big" buffers. */
> > +		if (i & 1)
> > +			buf_size = page_size +
> > +					(rand() % (MAX_MSG_SIZE - page_size));
> > +		else
> > +			buf_size = 1 + (rand() % page_size);
> > +
> > +		buf_size = min(buf_size, recv_buf_size);
> > +
> > +		buf = malloc(buf_size);
> > +
> > +		if (!buf) {
> > +			perror("malloc");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +
> > +		memset(buf, rand() & 0xff, buf_size);
> > +		/* Set at least one MSG_EOR + some random. */
> > +
> > +		send_size = send(fd, buf, buf_size, 0);
> > +
> > +		if (send_size < 0) {
> > +			perror("send");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +
> > +		if (send_size != buf_size) {
> > +			fprintf(stderr, "Invalid send size\n");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +
> > +		/* In theory the implementation isn't required to transmit
> > +		 * these packets in order, so we use this SYNC control message
> > +		 * so that server and client coordinate sending and receiving
> > +		 * one packet at a time. The client sends a packet and waits
> > +		 * until it has been received before sending another.
> > +		 */
> > +		control_writeln("PKTSENT");
> > +		control_expectln("PKTRECV");
> > +
> > +		/* Send the server a hash of the packet */
> > +		curr_hash = hash_djb2(buf, buf_size);
> > +		control_writeulong(curr_hash);
> > +		free(buf);
> > +	}
> > +
> > +	control_writeln("SENDDONE");
> > +	close(fd);
> > +}
> > +
> > +static void test_dgram_msg_bounds_server(const struct test_opts *opts)
> > +{
> > +	const unsigned long msg_cnt = 16;
> > +	unsigned long sock_buf_size;
> > +	struct msghdr msg = {0};
> > +	struct iovec iov = {0};
> > +	char buf[MAX_MSG_SIZE];
> > +	socklen_t len;
> > +	int fd;
> > +	int i;
> > +
> > +	fd = vsock_dgram_bind(VMADDR_CID_ANY, 1234);
> > +
> > +	if (fd < 0) {
> > +		perror("bind");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Set receive buffer to maximum */
> > +	sock_buf_size = -1;
> > +	if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF,
> > +		       &sock_buf_size, sizeof(sock_buf_size))) {
> > +		perror("setsockopt(SO_RECVBUF)");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Retrieve the receive buffer size */
> > +	len = sizeof(sock_buf_size);
> > +	if (getsockopt(fd, SOL_SOCKET, SO_RCVBUF,
> > +		       &sock_buf_size, &len)) {
> > +		perror("getsockopt(SO_RECVBUF)");
> > +		exit(EXIT_FAILURE);
> > +	}
> > +
> > +	/* Client ready to receive parameters */
> > +	control_expectln("CLNTREADY");
> > +
> > +	control_writeulong(msg_cnt);
> > +	control_writeulong(sock_buf_size);
> > +
> > +	/* Ready to receive data. */
> > +	control_writeln("SRVREADY");
> > +
> > +	iov.iov_base = buf;
> > +	iov.iov_len = sizeof(buf);
> > +	msg.msg_iov = &iov;
> > +	msg.msg_iovlen = 1;
> > +
> > +	for (i = 0; i < msg_cnt; i++) {
> > +		unsigned long remote_hash;
> > +		unsigned long curr_hash;
> > +		ssize_t recv_size;
> > +
> > +		control_expectln("PKTSENT");
> > +		recv_size = recvmsg(fd, &msg, 0);
> > +		control_writeln("PKTRECV");
> > +
> > +		if (!recv_size)
> > +			break;
> > +
> > +		if (recv_size < 0) {
> > +			perror("recvmsg");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +
> > +		curr_hash = hash_djb2(msg.msg_iov[0].iov_base, recv_size);
> > +		remote_hash = control_readulong();
> > +
> > +		if (curr_hash != remote_hash) {
> > +			fprintf(stderr, "Message bounds broken\n");
> > +			exit(EXIT_FAILURE);
> > +		}
> > +	}
> > +
> > +	close(fd);
> > +}
> > +
> >  static struct test_case test_cases[] = {
> >  	{
> >  		.name = "SOCK_STREAM connection reset",
> > @@ -1128,6 +1535,31 @@ static struct test_case test_cases[] = {
> >  		.run_client = test_stream_virtio_skb_merge_client,
> >  		.run_server = test_stream_virtio_skb_merge_server,
> >  	},
> > +	{
> > +		.name = "SOCK_DGRAM client sendto",
> > +		.run_client = test_dgram_sendto_client,
> > +		.run_server = test_dgram_sendto_server,
> > +	},
> > +	{
> > +		.name = "SOCK_DGRAM client connect",
> > +		.run_client = test_dgram_connect_client,
> > +		.run_server = test_dgram_connect_server,
> > +	},
> > +	{
> > +		.name = "SOCK_DGRAM multiple connections using sendto",
> > +		.run_client = test_dgram_multiconn_sendto_client,
> > +		.run_server = test_dgram_multiconn_sendto_server,
> > +	},
> > +	{
> > +		.name = "SOCK_DGRAM multiple connections using send",
> > +		.run_client = test_dgram_multiconn_send_client,
> > +		.run_server = test_dgram_multiconn_send_server,
> > +	},
> > +	{
> > +		.name = "SOCK_DGRAM msg bounds",
> > +		.run_client = test_dgram_msg_bounds_client,
> > +		.run_server = test_dgram_msg_bounds_server,
> > +	},
> >  	{},
> >  };
> >  
> >