[dpdk-dev] [PATCH v3 13/20] vfio: add multiprocess support.

Anatoly Burakov anatoly.burakov at intel.com
Wed May 28 16:38:10 CEST 2014


Since VFIO cannot be used to map the same device twice, secondary
processes receive the device/group fd's by means of communicating over a
local socket. Only group and container fd's should be sent, as device
fd's can be obtained via ioctl() calls' on the group fd.

For multiprocess, VFIO distinguishes between existing but unused groups
(e.g. grups that aren't bound to VFIO driver) and non-existing groups in
order to know if the secondary process requests a valid group, or if
secondary process requests something that doesn't exist.

VFIO multiprocess sync communicates over a simple protocol. It defines
two requests - request for group fd, and request for container fd.
Possible replies are: SOCKET_OK (an OK signal), SOCKET_ERR (error
signal) and SOCKET_NO_FD (a signal that indicates that the requested
VFIO group is valid, but no fd is present for that group - indicating
that the respective group is simply not bound to VFIO driver).

Here is the logic in a nutshell:

1. secondary process sends SOCKET_REQ_CONTAINER or SOCKET_REQ_GROUP
1a. in case of SOCKET_REQ_GROUP, client also then sends group number
2. primary process receives message
2a. in case of invalid group, SOCKET_ERR is sent back to secondary
2b. in case of unbound group, SOCKET_NO_FD is sent back to secondary
2c. in case of valid group, SOCKET_OK is sent and followed by fd
3. socket is closed

in case of any error, socket is closed and SOCKET_ERR is sent.

Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
 lib/librte_eal/linuxapp/eal/Makefile               |   1 +
 lib/librte_eal/linuxapp/eal/eal_pci_vfio.c         |  79 ++++-
 lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c | 395 +++++++++++++++++++++
 lib/librte_eal/linuxapp/eal/include/eal_pci_init.h |  19 +
 4 files changed, 492 insertions(+), 2 deletions(-)
 create mode 100644 lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c

diff --git a/lib/librte_eal/linuxapp/eal/Makefile b/lib/librte_eal/linuxapp/eal/Makefile
index cb87f8a..572d173 100644
--- a/lib/librte_eal/linuxapp/eal/Makefile
+++ b/lib/librte_eal/linuxapp/eal/Makefile
@@ -59,6 +59,7 @@ SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_log.c
 SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_pci.c
 SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_pci_uio.c
 SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_pci_vfio.c
+SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_pci_vfio_mp_sync.c
 SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_debug.c
 SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_lcore.c
 SRCS-$(CONFIG_RTE_LIBRTE_EAL_LINUXAPP) += eal_timer.c
diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
index e1d6973..f0d4f55 100644
--- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
@@ -303,7 +303,7 @@ pci_vfio_setup_interrupts(struct rte_pci_device *dev, int vfio_dev_fd)
 }
 
 /* open container fd or get an existing one */
-static int
+int
 pci_vfio_get_container_fd(void)
 {
 	int ret, vfio_container_fd;
@@ -333,13 +333,36 @@ pci_vfio_get_container_fd(void)
 		}
 
 		return vfio_container_fd;
+	} else {
+		/*
+		 * if we're in a secondary process, request container fd from the
+		 * primary process via our socket
+		 */
+		int socket_fd;
+		if ((socket_fd = vfio_mp_sync_connect_to_primary()) < 0) {
+			RTE_LOG(ERR, EAL, "  cannot connect to primary process!\n");
+			return -1;
+		}
+		if (vfio_mp_sync_send_request(socket_fd, SOCKET_REQ_CONTAINER) < 0) {
+			RTE_LOG(ERR, EAL, "  cannot request container fd!\n");
+			close(socket_fd);
+			return -1;
+		}
+		vfio_container_fd = vfio_mp_sync_receive_fd(socket_fd);
+		if (vfio_container_fd < 0) {
+			RTE_LOG(ERR, EAL, "  cannot get container fd!\n");
+			close(socket_fd);
+			return -1;
+		}
+		close(socket_fd);
+		return vfio_container_fd;
 	}
 
 	return -1;
 }
 
 /* open group fd or get an existing one */
-static int
+int
 pci_vfio_get_group_fd(int iommu_group_no)
 {
 	int i;
@@ -375,6 +398,44 @@ pci_vfio_get_group_fd(int iommu_group_no)
 		vfio_cfg.vfio_groups[vfio_cfg.vfio_group_idx].fd = vfio_group_fd;
 		return vfio_group_fd;
 	}
+	/* if we're in a secondary process, request group fd from the primary
+	 * process via our socket
+	 */
+	else {
+		int socket_fd, ret;
+		if ((socket_fd = vfio_mp_sync_connect_to_primary()) < 0) {
+			RTE_LOG(ERR, EAL, "  cannot connect to primary process!\n");
+			return -1;
+		}
+		if (vfio_mp_sync_send_request(socket_fd, SOCKET_REQ_GROUP) < 0) {
+			RTE_LOG(ERR, EAL, "  cannot request container fd!\n");
+			close(socket_fd);
+			return -1;
+		}
+		if (vfio_mp_sync_send_request(socket_fd, iommu_group_no) < 0) {
+			RTE_LOG(ERR, EAL, "  cannot send group number!\n");
+			close(socket_fd);
+			return -1;
+		}
+		ret = vfio_mp_sync_receive_request(socket_fd);
+		switch (ret) {
+		case SOCKET_NO_FD:
+			close(socket_fd);
+			return 0;
+		case SOCKET_OK:
+			vfio_group_fd = vfio_mp_sync_receive_fd(socket_fd);
+			/* if we got the fd, return it */
+			if (vfio_group_fd > 0) {
+				close(socket_fd);
+				return vfio_group_fd;
+			}
+			/* fall-through on error */
+		default:
+			RTE_LOG(ERR, EAL, "  cannot get container fd!\n");
+			close(socket_fd);
+			return -1;
+		}
+	}
 	return -1;
 }
 
@@ -602,6 +663,20 @@ pci_vfio_map_resource(struct rte_pci_device *dev)
 		/* get number of registers (up to BAR5) */
 		vfio_res->nb_maps = RTE_MIN((int) device_info.num_regions,
 				VFIO_PCI_BAR5_REGION_INDEX + 1);
+	} else {
+		/* if we're in a secondary process, just find our tailq entry */
+		TAILQ_FOREACH(vfio_res, pci_res_list, next) {
+			if (memcmp(&vfio_res->pci_addr, &dev->addr, sizeof(dev->addr)))
+				continue;
+			break;
+		}
+		/* if we haven't found our tailq entry, something's wrong */
+		if (vfio_res == NULL) {
+			RTE_LOG(ERR, EAL, "  %s cannot find TAILQ entry for PCI device!\n",
+					pci_addr);
+			close(vfio_dev_fd);
+			return -1;
+		}
 	}
 
 	/* map BARs */
diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c b/lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c
new file mode 100644
index 0000000..26dbaa5
--- /dev/null
+++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c
@@ -0,0 +1,395 @@
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <string.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+
+/* sys/un.h with __USE_MISC uses strlen, which is unsafe and should not be used. */
+#ifdef __USE_MISC
+#define REMOVED_USE_MISC
+#undef __USE_MISC
+#endif
+#include <sys/un.h>
+/* make sure we redefine __USE_MISC only if it was previously undefined */
+#ifdef REMOVED_USE_MISC
+#define __USE_MISC
+#undef REMOVED_USE_MISC
+#endif
+
+#include <rte_log.h>
+#include <rte_pci.h>
+#include <rte_tailq.h>
+#include <rte_eal_memconfig.h>
+#include <rte_malloc.h>
+
+#include "eal_filesystem.h"
+#include "eal_pci_init.h"
+
+/**
+ * @file
+ * VFIO socket for communication between primary and secondary processes.
+ *
+ * This file is only compiled if CONFIG_RTE_EAL_VFIO is set to "y".
+ */
+
+#ifdef VFIO_PRESENT
+
+#define SOCKET_PATH_FMT "%s/.%s_mp_socket"
+#define CMSGLEN (CMSG_LEN(sizeof(int)))
+#define FD_TO_CMSGHDR(fd, chdr) \
+		do {\
+			(chdr).cmsg_len = CMSGLEN;\
+			(chdr).cmsg_level = SOL_SOCKET;\
+			(chdr).cmsg_type = SCM_RIGHTS;\
+			memcpy((chdr).__cmsg_data, &(fd), sizeof(fd));\
+		} while (0)
+#define CMSGHDR_TO_FD(chdr, fd) \
+			memcpy(&(fd), (chdr).__cmsg_data, sizeof(fd))
+
+static pthread_t socket_thread;
+static int mp_socket_fd;
+
+
+/* get socket path (/var/run if root, $HOME otherwise) */
+static void
+get_socket_path(char *buffer, int bufsz)
+{
+	const char *dir = "/var/run";
+	const char *home_dir = getenv("HOME");
+
+	if (getuid() != 0 && home_dir != NULL)
+		dir = home_dir;
+
+	/* use current prefix as file path */
+	rte_snprintf(buffer, bufsz, SOCKET_PATH_FMT, dir,
+			internal_config.hugefile_prefix);
+}
+
+
+
+/*
+ * data flow for socket comm protocol:
+ * 1. client sends SOCKET_REQ_CONTAINER or SOCKET_REQ_GROUP
+ * 1a. in case of SOCKET_REQ_GROUP, client also then sends group number
+ * 2. server receives message
+ * 2a. in case of invalid group, SOCKET_ERR is sent back to client
+ * 2b. in case of unbound group, SOCKET_NO_FD is sent back to client
+ * 2c. in case of valid group, SOCKET_OK is sent and immediately followed by fd
+ *
+ * in case of any error, socket is closed.
+ */
+
+/* send a request, return -1 on error */
+int
+vfio_mp_sync_send_request(int socket, int req)
+{
+	struct msghdr hdr;
+	struct iovec iov;
+	int buf;
+	int ret;
+
+	memset(&hdr, 0, sizeof(hdr));
+
+	buf = req;
+
+	hdr.msg_iov = &iov;
+	hdr.msg_iovlen = 1;
+	iov.iov_base = (char *) &buf;
+	iov.iov_len = sizeof(buf);
+
+	ret = sendmsg(socket, &hdr, 0);
+	if (ret < 0)
+		return -1;
+	return 0;
+}
+
+/* receive a request and return it */
+int
+vfio_mp_sync_receive_request(int socket)
+{
+	int buf;
+	struct msghdr hdr;
+	struct iovec iov;
+	int ret, req;
+
+	memset(&hdr, 0, sizeof(hdr));
+
+	buf = SOCKET_ERR;
+
+	hdr.msg_iov = &iov;
+	hdr.msg_iovlen = 1;
+	iov.iov_base = (char *) &buf;
+	iov.iov_len = sizeof(buf);
+
+	ret = recvmsg(socket, &hdr, 0);
+	if (ret < 0)
+		return -1;
+
+	req = buf;
+
+	return req;
+}
+
+/* send OK in message, fd in control message */
+int
+vfio_mp_sync_send_fd(int socket, int fd)
+{
+	int buf;
+	struct msghdr hdr;
+	struct cmsghdr *chdr;
+	char chdr_buf[CMSGLEN];
+	struct iovec iov;
+	int ret;
+
+	chdr = (struct cmsghdr *) chdr_buf;
+	memset(chdr, 0, sizeof(chdr_buf));
+	memset(&hdr, 0, sizeof(hdr));
+
+	hdr.msg_iov = &iov;
+	hdr.msg_iovlen = 1;
+	iov.iov_base = (char *) &buf;
+	iov.iov_len = sizeof(buf);
+	hdr.msg_control = chdr;
+	hdr.msg_controllen = CMSGLEN;
+
+	buf = SOCKET_OK;
+	FD_TO_CMSGHDR(fd, *chdr);
+
+	ret = sendmsg(socket, &hdr, 0);
+	if (ret < 0)
+		return -1;
+	return 0;
+}
+
+/* receive OK in message, fd in control message */
+int
+vfio_mp_sync_receive_fd(int socket)
+{
+	int buf;
+	struct msghdr hdr;
+	struct cmsghdr *chdr;
+	char chdr_buf[CMSGLEN];
+	struct iovec iov;
+	int ret, req, fd;
+
+	buf = SOCKET_ERR;
+
+	chdr = (struct cmsghdr *) chdr_buf;
+	memset(chdr, 0, sizeof(chdr_buf));
+	memset(&hdr, 0, sizeof(hdr));
+
+	hdr.msg_iov = &iov;
+	hdr.msg_iovlen = 1;
+	iov.iov_base = (char *) &buf;
+	iov.iov_len = sizeof(buf);
+	hdr.msg_control = chdr;
+	hdr.msg_controllen = CMSGLEN;
+
+	ret = recvmsg(socket, &hdr, 0);
+	if (ret < 0)
+		return -1;
+
+	req = buf;
+
+	if (req != SOCKET_OK)
+		return -1;
+
+	CMSGHDR_TO_FD(*chdr, fd);
+
+	return fd;
+}
+
+/* connect socket_fd in secondary process to the primary process's socket */
+int
+vfio_mp_sync_connect_to_primary(void)
+{
+	struct sockaddr_un addr;
+	socklen_t sockaddr_len;
+	int socket_fd;
+
+	/* set up a socket */
+	socket_fd = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+	if (socket_fd < 0) {
+		RTE_LOG(ERR, EAL, "Failed to create socket!\n");
+		return -1;
+	}
+
+	get_socket_path(addr.sun_path, sizeof(addr.sun_path));
+	addr.sun_family = AF_UNIX;
+
+	sockaddr_len = sizeof(struct sockaddr_un);
+
+	if (connect(socket_fd, (struct sockaddr *) &addr, sockaddr_len) == 0)
+		return socket_fd;
+
+	/* if connect failed */
+	close(socket_fd);
+	return -1;
+}
+
+
+
+/*
+ * socket listening thread for primary process
+ */
+static __attribute__((noreturn)) void *
+pci_vfio_mp_sync_thread(void __rte_unused * arg)
+{
+	int ret, fd, vfio_group_no;
+
+	/* wait for requests on the socket */
+	for (;;) {
+		int conn_sock;
+		struct sockaddr_un addr;
+		socklen_t sockaddr_len = sizeof(addr);
+
+		/* this is a blocking call */
+		conn_sock = accept(mp_socket_fd, (struct sockaddr *) &addr,
+				&sockaddr_len);
+
+		/* just restart on error */
+		if (conn_sock == -1)
+			continue;
+
+		/* set socket to linger after close */
+		struct linger l;
+		l.l_onoff = 1;
+		l.l_linger = 60;
+		setsockopt(conn_sock, SOL_SOCKET, SO_LINGER, &l, sizeof(l));
+
+		ret = vfio_mp_sync_receive_request(conn_sock);
+
+		switch (ret) {
+		case SOCKET_REQ_CONTAINER:
+			fd = pci_vfio_get_container_fd();
+			if (fd < 0)
+				vfio_mp_sync_send_request(conn_sock, SOCKET_ERR);
+			else
+				vfio_mp_sync_send_fd(conn_sock, fd);
+			break;
+		case SOCKET_REQ_GROUP:
+			/* wait for group number */
+			vfio_group_no = vfio_mp_sync_receive_request(conn_sock);
+			if (vfio_group_no < 0) {
+				close(conn_sock);
+				continue;
+			}
+
+			fd = pci_vfio_get_group_fd(vfio_group_no);
+
+			if (fd < 0)
+				vfio_mp_sync_send_request(conn_sock, SOCKET_ERR);
+			/* if VFIO group exists but isn't bound to VFIO driver */
+			else if (fd == 0)
+				vfio_mp_sync_send_request(conn_sock, SOCKET_NO_FD);
+			/* if group exists and is bound to VFIO driver */
+			else {
+				vfio_mp_sync_send_request(conn_sock, SOCKET_OK);
+				vfio_mp_sync_send_fd(conn_sock, fd);
+			}
+			break;
+		default:
+			vfio_mp_sync_send_request(conn_sock, SOCKET_ERR);
+			break;
+		}
+		close(conn_sock);
+	}
+}
+
+static int
+vfio_mp_sync_socket_setup(void)
+{
+	int ret, socket_fd;
+	struct sockaddr_un addr;
+	socklen_t sockaddr_len;
+
+	/* set up a socket */
+	socket_fd = socket(AF_UNIX, SOCK_SEQPACKET, 0);
+	if (socket_fd < 0) {
+		RTE_LOG(ERR, EAL, "Failed to create socket!\n");
+		return -1;
+	}
+
+	get_socket_path(addr.sun_path, sizeof(addr.sun_path));
+	addr.sun_family = AF_UNIX;
+
+	sockaddr_len = sizeof(struct sockaddr_un);
+
+	unlink(addr.sun_path);
+
+	ret = bind(socket_fd, (struct sockaddr *) &addr, sockaddr_len);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to bind socket: %s!\n", strerror(errno));
+		close(socket_fd);
+		return -1;
+	}
+
+	ret = listen(socket_fd, 50);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to listen: %s!\n", strerror(errno));
+		close(socket_fd);
+		return -1;
+	}
+
+	/* save the socket in local configuration */
+	mp_socket_fd = socket_fd;
+
+	return 0;
+}
+
+/*
+ * set up a local socket and tell it to listen for incoming connections
+ */
+int
+pci_vfio_mp_sync_setup(void)
+{
+	int ret;
+
+	if (vfio_mp_sync_socket_setup() < 0) {
+		RTE_LOG(ERR, EAL, "Failed to set up local socket!\n");
+		return -1;
+	}
+
+	ret = pthread_create(&socket_thread, NULL,
+			pci_vfio_mp_sync_thread, NULL);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Failed to create thread for communication with "
+				"secondary processes!\n");
+		close(mp_socket_fd);
+		return -1;
+	}
+	return 0;
+}
+
+#endif
diff --git a/lib/librte_eal/linuxapp/eal/include/eal_pci_init.h b/lib/librte_eal/linuxapp/eal/include/eal_pci_init.h
index 23fb3c3..45846cc 100644
--- a/lib/librte_eal/linuxapp/eal/include/eal_pci_init.h
+++ b/lib/librte_eal/linuxapp/eal/include/eal_pci_init.h
@@ -71,9 +71,28 @@ int pci_uio_map_resource(struct rte_pci_device *dev);
 
 int pci_vfio_enable(void);
 int pci_vfio_is_enabled(void);
+int pci_vfio_mp_sync_setup(void);
 
 /* map VFIO resource prototype */
 int pci_vfio_map_resource(struct rte_pci_device *dev);
+int pci_vfio_get_group_fd(int iommu_group_fd);
+int pci_vfio_get_container_fd(void);
+
+/*
+ * Function prototypes for VFIO multiprocess sync functions
+ */
+int vfio_mp_sync_send_request(int socket, int req);
+int vfio_mp_sync_receive_request(int socket);
+int vfio_mp_sync_send_fd(int socket, int fd);
+int vfio_mp_sync_receive_fd(int socket);
+int vfio_mp_sync_connect_to_primary(void);
+
+/* socket comm protocol definitions */
+#define SOCKET_REQ_CONTAINER 0x100
+#define SOCKET_REQ_GROUP 0x200
+#define SOCKET_OK 0x0
+#define SOCKET_NO_FD 0x1
+#define SOCKET_ERR 0xFF
 
 /*
  * we don't need to store device fd's anywhere since they can be obtained from
-- 
1.8.1.4



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