/****************************************************************************** * xenstore.c * * Low-level kernel interface to the XenStore. * * Copyright (C) 2005 Rusty Russell, IBM Corporation * Copyright (C) 2009,2010 Spectra Logic Corporation * * This file may be distributed separately from the Linux kernel, or * incorporated into other software packages, subject to the following license: * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this source file (the "Software"), to deal in the Software without * restriction, including without limitation the rights to use, copy, modify, * merge, publish, distribute, sublicense, and/or sell copies of the Software, * and to permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /** * \file xenstore.c * \brief XenStore interface * * The XenStore interface is a simple storage system that is a means of * communicating state and configuration data between the Xen Domain 0 * and the various guest domains. All configuration data other than * a small amount of essential information required during the early * boot process of launching a Xen aware guest, is managed using the * XenStore. * * The XenStore is ASCII string based, and has a structure and semantics * similar to a filesystem. There are files and directories, the directories * able to contain files or other directories. The depth of the hierachy * is only limited by the XenStore's maximum path length. * * The communication channel between the XenStore service and other * domains is via two, guest specific, ring buffers in a shared memory * area. One ring buffer is used for communicating in each direction. * The grant table references for this shared memory are given to the * guest either via the xen_start_info structure for a fully para- * virtualized guest, or via HVM hypercalls for a hardware virtualized * guest. * * The XenStore communication relies on an event channel and thus * interrupts. For this reason, the attachment of the XenStore * relies on an interrupt driven configuration hook to hold off * boot processing until communication with the XenStore service * can be established. * * Several Xen services depend on the XenStore, most notably the * XenBus used to discover and manage Xen devices. These services * are implemented as NewBus child attachments to a bus exported * by this XenStore driver. */ static struct xs_watch *find_watch(const char *token); MALLOC_DEFINE(M_XENSTORE, "xenstore", "XenStore data and results"); /** * Pointer to shared memory communication structures allowing us * to communicate with the XenStore service. * * When operating in full PV mode, this pointer is set early in kernel * startup from within xen_machdep.c. In HVM mode, we use hypercalls * to get the guest frame number for the shared page and then map it * into kva. See xs_init() for details. */ struct xenstore_domain_interface *xen_store; /*-------------------------- Private Data Structures ------------------------*/ /** * Structure capturing messages received from the XenStore service. */ struct xs_stored_msg { TAILQ_ENTRY(xs_stored_msg) list; struct xsd_sockmsg hdr; union { /* Queued replies. */ struct { char *body; } reply; /* Queued watch events. */ struct { struct xs_watch *handle; const char **vec; u_int vec_size; } watch; } u; }; TAILQ_HEAD(xs_stored_msg_list, xs_stored_msg); /** * Container for all XenStore related state. */ struct xs_softc { /** Newbus device for the XenStore. */ device_t xs_dev; /** * Lock serializing access to ring producer/consumer * indexes. Use of this lock guarantees that wakeups * of blocking readers/writers are not missed due to * races with the XenStore service. */ struct mtx ring_lock; /* * Mutex used to insure exclusive access to the outgoing * communication ring. We use a lock type that can be * held while sleeping so that xs_write() can block waiting * for space in the ring to free up, without allowing another * writer to come in and corrupt a partial message write. */ struct sx request_mutex; /** * A list of replies to our requests. * * The reply list is filled by xs_rcv_thread(). It * is consumed by the context that issued the request * to which a reply is made. The requester blocks in * xs_read_reply(). * * /note Only one requesting context can be active at a time. * This is guaranteed by the request_mutex and insures * that the requester sees replies matching the order * of its requests. */ struct xs_stored_msg_list reply_list; /** Lock protecting the reply list. */ struct mtx reply_lock; /** * List of registered watches. */ struct xs_watch_list registered_watches; /** Lock protecting the registered watches list. */ struct mtx registered_watches_lock; /** * List of pending watch callback events. */ struct xs_stored_msg_list watch_events; /** Lock protecting the watch calback list. */ struct mtx watch_events_lock; /** * Sleepable lock used to prevent VM suspension while a * xenstore transaction is outstanding. * * Each active transaction holds a shared lock on the * suspend mutex. Our suspend method blocks waiting * to acquire an exclusive lock. This guarantees that * suspend processing will only proceed once all active * transactions have been retired. */ struct sx suspend_mutex; /** * The processid of the xenwatch thread. */ pid_t xenwatch_pid; /** * Sleepable mutex used to gate the execution of XenStore * watch event callbacks. * * xenwatch_thread holds an exclusive lock on this mutex * while delivering event callbacks, and xenstore_unregister_watch() * uses an exclusive lock of this mutex to guarantee that no * callbacks of the just unregistered watch are pending * before returning to its caller. */ struct sx xenwatch_mutex; /** * The HVM guest pseudo-physical frame number. This is Xen's mapping * of the true machine frame number into our "physical address space". */ unsigned long gpfn; /** * The event channel for communicating with the * XenStore service. */ int evtchn; /** Handle for XenStore interrupts. */ xen_intr_handle_t xen_intr_handle; /** * Interrupt driven config hook allowing us to defer * attaching children until interrupts (and thus communication * with the XenStore service) are available. */ struct intr_config_hook xs_attachcb; /** * Xenstore is a user-space process that usually runs in Dom0, * so if this domain is booting as Dom0, xenstore wont we accessible, * and we have to defer the initialization of xenstore related * devices to later (when xenstore is started). */ bool initialized; /** * Task to run when xenstore is initialized (Dom0 only), will * take care of attaching xenstore related devices. */ struct task xs_late_init; }; /*-------------------------------- Global Data ------------------------------*/ static struct xs_softc xs; /*------------------------- Private Utility Functions -----------------------*/ /** * Count and optionally record pointers to a number of NUL terminated * strings in a buffer. * * \param strings A pointer to a contiguous buffer of NUL terminated strings. * \param dest An array to store pointers to each string found in strings. * \param len The length of the buffer pointed to by strings. * * \return A count of the number of strings found. */ static u_int extract_strings(const char *strings, const char **dest, u_int len) { u_int num; const char *p; for (p = strings, num = 0; p < strings + len; p += strlen(p) + 1) { if (dest != NULL) *dest++ = p; num++; } return (num); } /** * Convert a contiguous buffer containing a series of NUL terminated * strings into an array of pointers to strings. * * The returned pointer references the array of string pointers which * is followed by the storage for the string data. It is the client's * responsibility to free this storage. * * The storage addressed by strings is free'd prior to split returning. * * \param strings A pointer to a contiguous buffer of NUL terminated strings. * \param len The length of the buffer pointed to by strings. * \param num The number of strings found and returned in the strings * array. * * \return An array of pointers to the strings found in the input buffer. */ static const char ** split(char *strings, u_int len, u_int *num) { const char **ret; /* Protect against unterminated buffers. */ if (len > 0) strings[len - 1] = '\0'; /* Count the strings. */ *num = extract_strings(strings, /*dest*/NULL, len); /* Transfer to one big alloc for easy freeing by the caller. */ ret = malloc(*num * sizeof(char *) + len, M_XENSTORE, M_WAITOK); memcpy(&ret[*num], strings, len); free(strings, M_XENSTORE); /* Extract pointers to newly allocated array. */ strings = (char *)&ret[*num]; (void)extract_strings(strings, /*dest*/ret, len); return (ret); } /*------------------------- Public Utility Functions -------------------------*/ /*------- API comments for these methods can be found in xenstorevar.h -------*/ struct sbuf * xs_join(const char *dir, const char *name) { struct sbuf *sb; sb = sbuf_new_auto(); sbuf_cat(sb, dir); if (name[0] != '\0') { sbuf_putc(sb, '/'); sbuf_cat(sb, name); } sbuf_finish(sb); return (sb); } /*-------------------- Low Level Communication Management --------------------*/ /** * Interrupt handler for the XenStore event channel. * * XenStore reads and writes block on "xen_store" for buffer * space. Wakeup any blocking operations when the XenStore * service has modified the queues. */ static void xs_intr(void * arg __unused /*__attribute__((unused))*/) { /* If xenstore has not been initialized, initialize it now */ if (!xs.initialized) { xs.initialized = true; /* * Since this task is probing and attaching devices we * have to hold the Giant lock. */ taskqueue_enqueue(taskqueue_swi_giant, &xs.xs_late_init); } /* * Hold ring lock across wakeup so that clients * cannot miss a wakeup. */ mtx_lock(&xs.ring_lock); wakeup(xen_store); mtx_unlock(&xs.ring_lock); } /** * Verify that the indexes for a ring are valid. * * The difference between the producer and consumer cannot * exceed the size of the ring. * * \param cons The consumer index for the ring to test. * \param prod The producer index for the ring to test. * * \retval 1 If indexes are in range. * \retval 0 If the indexes are out of range. */ static int xs_check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod) { return ((prod - cons) <= XENSTORE_RING_SIZE); } /** * Return a pointer to, and the length of, the contiguous * free region available for output in a ring buffer. * * \param cons The consumer index for the ring. * \param prod The producer index for the ring. * \param buf The base address of the ring's storage. * \param len The amount of contiguous storage available. * * \return A pointer to the start location of the free region. */ static void * xs_get_output_chunk(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod, char *buf, uint32_t *len) { *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod); if ((XENSTORE_RING_SIZE - (prod - cons)) < *len) *len = XENSTORE_RING_SIZE - (prod - cons); return (buf + MASK_XENSTORE_IDX(prod)); } /** * Return a pointer to, and the length of, the contiguous * data available to read from a ring buffer. * * \param cons The consumer index for the ring. * \param prod The producer index for the ring. * \param buf The base address of the ring's storage. * \param len The amount of contiguous data available to read. * * \return A pointer to the start location of the available data. */ static const void * xs_get_input_chunk(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod, const char *buf, uint32_t *len) { *len = XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(cons); if ((prod - cons) < *len) *len = prod - cons; return (buf + MASK_XENSTORE_IDX(cons)); } /** * Transmit data to the XenStore service. * * \param tdata A pointer to the contiguous data to send. * \param len The amount of data to send. * * \return On success 0, otherwise an errno value indicating the * cause of failure. * * \invariant Called from thread context. * \invariant The buffer pointed to by tdata is at least len bytes * in length. * \invariant xs.request_mutex exclusively locked. */ static int xs_write_store(const void *tdata, unsigned len) { XENSTORE_RING_IDX cons, prod; const char *data = (const char *)tdata; int error; sx_assert(&xs.request_mutex, SX_XLOCKED); while (len != 0) { void *dst; u_int avail; /* Hold lock so we can't miss wakeups should we block. */ mtx_lock(&xs.ring_lock); cons = xen_store->req_cons; prod = xen_store->req_prod; if ((prod - cons) == XENSTORE_RING_SIZE) { /* * Output ring is full. Wait for a ring event. * * Note that the events from both queues * are combined, so being woken does not * guarantee that data exist in the read * ring. * * To simplify error recovery and the retry, * we specify PDROP so our lock is *not* held * when msleep returns. */ error = msleep(xen_store, &xs.ring_lock, PCATCH|PDROP, "xbwrite", /*timeout*/0); if (error && error != EWOULDBLOCK) return (error); /* Try again. */ continue; } mtx_unlock(&xs.ring_lock); /* Verify queue sanity. */ if (!xs_check_indexes(cons, prod)) { xen_store->req_cons = xen_store->req_prod = 0; return (EIO); } dst = xs_get_output_chunk(cons, prod, xen_store->req, &avail); if (avail > len) avail = len; memcpy(dst, data, avail); data += avail; len -= avail; /* * The store to the producer index, which indicates * to the other side that new data has arrived, must * be visible only after our copy of the data into the * ring has completed. */ wmb(); xen_store->req_prod += avail; /* * xen_intr_signal() implies mb(). The other side will see * the change to req_prod at the time of the interrupt. */ xen_intr_signal(xs.xen_intr_handle); } return (0); } /** * Receive data from the XenStore service. * * \param tdata A pointer to the contiguous buffer to receive the data. * \param len The amount of data to receive. * * \return On success 0, otherwise an errno value indicating the * cause of failure. * * \invariant Called from thread context. * \invariant The buffer pointed to by tdata is at least len bytes * in length. * * \note xs_read does not perform any internal locking to guarantee * serial access to the incoming ring buffer. However, there * is only one context processing reads: xs_rcv_thread(). */ static int xs_read_store(void *tdata, unsigned len) { XENSTORE_RING_IDX cons, prod; char *data = (char *)tdata; int error; while (len != 0) { u_int avail; const char *src; /* Hold lock so we can't miss wakeups should we block. */ mtx_lock(&xs.ring_lock); cons = xen_store->rsp_cons; prod = xen_store->rsp_prod; if (cons == prod) { /* * Nothing to read. Wait for a ring event. * * Note that the events from both queues * are combined, so being woken does not * guarantee that data exist in the read * ring. * * To simplify error recovery and the retry, * we specify PDROP so our lock is *not* held * when msleep returns. */ error = msleep(xen_store, &xs.ring_lock, PCATCH|PDROP, "xbread", /*timeout*/0); if (error && error != EWOULDBLOCK) return (error); continue; } mtx_unlock(&xs.ring_lock); /* Verify queue sanity. */ if (!xs_check_indexes(cons, prod)) { xen_store->rsp_cons = xen_store->rsp_prod = 0; return (EIO); } src = xs_get_input_chunk(cons, prod, xen_store->rsp, &avail); if (avail > len) avail = len; /* * Insure the data we read is related to the indexes * we read above. */ rmb(); memcpy(data, src, avail); data += avail; len -= avail; /* * Insure that the producer of this ring does not see * the ring space as free until after we have copied it * out. */ mb(); xen_store->rsp_cons += avail; /* * xen_intr_signal() implies mb(). The producer will see * the updated consumer index when the event is delivered. */ xen_intr_signal(xs.xen_intr_handle); } return (0); } /*----------------------- Received Message Processing ------------------------*/ /** * Block reading the next message from the XenStore service and * process the result. * * \param type The returned type of the XenStore message received. * * \return 0 on success. Otherwise an errno value indicating the * type of failure encountered. */ static int xs_process_msg(enum xsd_sockmsg_type *type) { struct xs_stored_msg *msg; char *body; int error; msg = malloc(sizeof(*msg), M_XENSTORE, M_WAITOK); error = xs_read_store(&msg->hdr, sizeof(msg->hdr)); if (error) { free(msg, M_XENSTORE); return (error); } body = malloc(msg->hdr.len + 1, M_XENSTORE, M_WAITOK); error = xs_read_store(body, msg->hdr.len); if (error) { free(body, M_XENSTORE); free(msg, M_XENSTORE); return (error); } body[msg->hdr.len] = '\0'; *type = msg->hdr.type; if (msg->hdr.type == XS_WATCH_EVENT) { msg->u.watch.vec = split(body, msg->hdr.len, &msg->u.watch.vec_size); mtx_lock(&xs.registered_watches_lock); msg->u.watch.handle = find_watch( msg->u.watch.vec[XS_WATCH_TOKEN]); if (msg->u.watch.handle != NULL) { mtx_lock(&xs.watch_events_lock); TAILQ_INSERT_TAIL(&xs.watch_events, msg, list); wakeup(&xs.watch_events); mtx_unlock(&xs.watch_events_lock); } else { free(msg->u.watch.vec, M_XENSTORE); free(msg, M_XENSTORE); } mtx_unlock(&xs.registered_watches_lock); } else { msg->u.reply.body = body; mtx_lock(&xs.reply_lock); TAILQ_INSERT_TAIL(&xs.reply_list, msg, list); wakeup(&xs.reply_list); mtx_unlock(&xs.reply_lock); } return (0); } /** * Thread body of the XenStore receive thread. * * This thread blocks waiting for data from the XenStore service * and processes and received messages. */ static void xs_rcv_thread(void *arg __unused) { int error; enum xsd_sockmsg_type type; for (;;) { error = xs_process_msg(&type); if (error) printf("XENSTORE error %d while reading message\n", error); } } /*---------------- XenStore Message Request/Reply Processing -----------------*/ /** * Filter invoked before transmitting any message to the XenStore service. * * The role of the filter may expand, but currently serves to manage * the interactions of messages with transaction state. * * \param request_msg_type The message type for the request. */ static inline void xs_request_filter(uint32_t request_msg_type) { if (request_msg_type == XS_TRANSACTION_START) sx_slock(&xs.suspend_mutex); } /** * Filter invoked after transmitting any message to the XenStore service. * * The role of the filter may expand, but currently serves to manage * the interactions of messages with transaction state. * * \param request_msg_type The message type for the original request. * \param reply_msg_type The message type for any received reply. * \param request_reply_error The error status from the attempt to send * the request or retrieve the reply. */ static inline void xs_reply_filter(uint32_t request_msg_type, uint32_t reply_msg_type, int request_reply_error) { /* * The count of transactions drops if we attempted * to end a transaction (even if that attempt fails * in error), we receive a transaction end acknowledgement, * or if our attempt to begin a transaction fails. */ if (request_msg_type == XS_TRANSACTION_END || (request_reply_error == 0 && reply_msg_type == XS_TRANSACTION_END) || (request_msg_type == XS_TRANSACTION_START && (request_reply_error != 0 || reply_msg_type == XS_ERROR))) sx_sunlock(&xs.suspend_mutex); } #define xsd_error_count (sizeof(xsd_errors) / sizeof(xsd_errors[0])) /** * Convert a XenStore error string into an errno number. * * \param errorstring The error string to convert. * * \return The errno best matching the input string. * * \note Unknown error strings are converted to EINVAL. */ static int xs_get_error(const char *errorstring) { u_int i; for (i = 0; i < xsd_error_count; i++) { if (!strcmp(errorstring, xsd_errors[i].errstring)) return (xsd_errors[i].errnum); } log(LOG_WARNING, "XENSTORE xen store gave: unknown error %s", errorstring); return (EINVAL); } /** * Block waiting for a reply to a message request. * * \param type The returned type of the reply. * \param len The returned body length of the reply. * \param result The returned body of the reply. * * \return 0 on success. Otherwise an errno indicating the * cause of failure. */ static int xs_read_reply(enum xsd_sockmsg_type *type, u_int *len, void **result) { struct xs_stored_msg *msg; char *body; int error; mtx_lock(&xs.reply_lock); while (TAILQ_EMPTY(&xs.reply_list)) { error = mtx_sleep(&xs.reply_list, &xs.reply_lock, PCATCH, "xswait", hz/10); if (error && error != EWOULDBLOCK) { mtx_unlock(&xs.reply_lock); return (error); } } msg = TAILQ_FIRST(&xs.reply_list); TAILQ_REMOVE(&xs.reply_list, msg, list); mtx_unlock(&xs.reply_lock); *type = msg->hdr.type; if (len) *len = msg->hdr.len; body = msg->u.reply.body; free(msg, M_XENSTORE); *result = body; return (0); } /** * Pass-thru interface for XenStore access by userland processes * via the XenStore device. * * Reply type and length data are returned by overwriting these * fields in the passed in request message. * * \param msg A properly formatted message to transmit to * the XenStore service. * \param result The returned body of the reply. * * \return 0 on success. Otherwise an errno indicating the cause * of failure. * * \note The returned result is provided in malloced storage and thus * must be free'd by the caller with 'free(result, M_XENSTORE); */ int xs_dev_request_and_reply(struct xsd_sockmsg *msg, void **result) { uint32_t request_type; int error; request_type = msg->type; xs_request_filter(request_type); sx_xlock(&xs.request_mutex); if ((error = xs_write_store(msg, sizeof(*msg) + msg->len)) == 0) error = xs_read_reply(&msg->type, &msg->len, result); sx_xunlock(&xs.request_mutex); xs_reply_filter(request_type, msg->type, error); return (error); } /** * Send a message with an optionally muti-part body to the XenStore service. * * \param t The transaction to use for this request. * \param request_type The type of message to send. * \param iovec Pointers to the body sections of the request. * \param num_vecs The number of body sections in the request. * \param len The returned length of the reply. * \param result The returned body of the reply. * * \return 0 on success. Otherwise an errno indicating * the cause of failure. * * \note The returned result is provided in malloced storage and thus * must be free'd by the caller with 'free(*result, M_XENSTORE); */ static int xs_talkv(struct xs_transaction t, enum xsd_sockmsg_type request_type, const struct iovec *iovec, u_int num_vecs, u_int *len, void **result) { struct xsd_sockmsg msg; void *ret = NULL; u_int i; int error; msg.tx_id = t.id; msg.req_id = 0; msg.type = request_type; msg.len = 0; for (i = 0; i < num_vecs; i++) msg.len += iovec[i].iov_len; xs_request_filter(request_type); sx_xlock(&xs.request_mutex); error = xs_write_store(&msg, sizeof(msg)); if (error) { printf("xs_talkv failed %d\n", error); goto error_lock_held; } for (i = 0; i < num_vecs; i++) { error = xs_write_store(iovec[i].iov_base, iovec[i].iov_len); if (error) { printf("xs_talkv failed %d\n", error); goto error_lock_held; } } error = xs_read_reply(&msg.type, len, &ret); error_lock_held: sx_xunlock(&xs.request_mutex); xs_reply_filter(request_type, msg.type, error); if (error) return (error); if (msg.type == XS_ERROR) { error = xs_get_error(ret); free(ret, M_XENSTORE); return (error); } /* Reply is either error or an echo of our request message type. */ KASSERT(msg.type == request_type, ("bad xenstore message type")); if (result) *result = ret; else free(ret, M_XENSTORE); return (0); } /** * Wrapper for xs_talkv allowing easy transmission of a message with * a single, contiguous, message body. * * \param t The transaction to use for this request. * \param request_type The type of message to send. * \param body The body of the request. * \param len The returned length of the reply. * \param result The returned body of the reply. * * \return 0 on success. Otherwise an errno indicating * the cause of failure. * * \note The returned result is provided in malloced storage and thus * must be free'd by the caller with 'free(*result, M_XENSTORE); */ static int xs_single(struct xs_transaction t, enum xsd_sockmsg_type request_type, const char *body, u_int *len, void **result) { struct iovec iovec; iovec.iov_base = (void *)(uintptr_t)body; iovec.iov_len = strlen(body) + 1; return (xs_talkv(t, request_type, &iovec, 1, len, result)); } /*------------------------- XenStore Watch Support ---------------------------*/ /** * Transmit a watch request to the XenStore service. * * \param path The path in the XenStore to watch. * \param tocken A unique identifier for this watch. * * \return 0 on success. Otherwise an errno indicating the * cause of failure. */ static int xs_watch(const char *path, const char *token) { struct iovec iov[2]; iov[0].iov_base = (void *)(uintptr_t) path; iov[0].iov_len = strlen(path) + 1; iov[1].iov_base = (void *)(uintptr_t) token; iov[1].iov_len = strlen(token) + 1; return (xs_talkv(XST_NIL, XS_WATCH, iov, 2, NULL, NULL)); } /** * Transmit an uwatch request to the XenStore service. * * \param path The path in the XenStore to watch. * \param tocken A unique identifier for this watch. * * \return 0 on success. Otherwise an errno indicating the * cause of failure. */ static int xs_unwatch(const char *path, const char *token) { struct iovec iov[2]; iov[0].iov_base = (void *)(uintptr_t) path; iov[0].iov_len = strlen(path) + 1; iov[1].iov_base = (void *)(uintptr_t) token; iov[1].iov_len = strlen(token) + 1; return (xs_talkv(XST_NIL, XS_UNWATCH, iov, 2, NULL, NULL)); } /** * Convert from watch token (unique identifier) to the associated * internal tracking structure for this watch. * * \param tocken The unique identifier for the watch to find. * * \return A pointer to the found watch structure or NULL. */ static struct xs_watch * find_watch(const char *token) { struct xs_watch *i, *cmp; cmp = (void *)strtoul(token, NULL, 16); LIST_FOREACH(i, &xs.registered_watches, list) if (i == cmp) return (i); return (NULL); } /** * Thread body of the XenStore watch event dispatch thread. */ static void xenwatch_thread(void *unused) { struct xs_stored_msg *msg; for (;;) { mtx_lock(&xs.watch_events_lock); while (TAILQ_EMPTY(&xs.watch_events)) mtx_sleep(&xs.watch_events, &xs.watch_events_lock, PWAIT | PCATCH, "waitev", hz/10); mtx_unlock(&xs.watch_events_lock); sx_xlock(&xs.xenwatch_mutex); mtx_lock(&xs.watch_events_lock); msg = TAILQ_FIRST(&xs.watch_events); if (msg) TAILQ_REMOVE(&xs.watch_events, msg, list); mtx_unlock(&xs.watch_events_lock); if (msg != NULL) { /* * XXX There are messages coming in with a NULL * XXX callback. This deserves further investigation; * XXX the workaround here simply prevents the kernel * XXX from panic'ing on startup. */ if (msg->u.watch.handle->callback != NULL) msg->u.watch.handle->callback( msg->u.watch.handle, (const char **)msg->u.watch.vec, msg->u.watch.vec_size); free(msg->u.watch.vec, M_XENSTORE); free(msg, M_XENSTORE); } sx_xunlock(&xs.xenwatch_mutex); } } /*----------- XenStore Configuration, Initialization, and Control ------------*/ /** * Setup communication channels with the XenStore service. * * \return On success, 0. Otherwise an errno value indicating the * type of failure. */ static int xs_init_comms(void) { int error; if (xen_store->rsp_prod != xen_store->rsp_cons) { log(LOG_WARNING, "XENSTORE response ring is not quiescent " "(%08x:%08x): fixing up\n", xen_store->rsp_cons, xen_store->rsp_prod); xen_store->rsp_cons = xen_store->rsp_prod; } xen_intr_unbind(&xs.xen_intr_handle); error = xen_intr_bind_local_port(xs.xs_dev, xs.evtchn, /*filter*/NULL, xs_intr, /*arg*/NULL, INTR_TYPE_NET|INTR_MPSAFE, &xs.xen_intr_handle); if (error) { log(LOG_WARNING, "XENSTORE request irq failed %i\n", error); return (error); } return (0); } /*------------------ Private Device Attachment Functions --------------------*/ static void xs_identify(driver_t *driver, device_t parent) { BUS_ADD_CHILD(parent, 0, "xenstore", 0); } /** * Probe for the existance of the XenStore. * * \param dev */ static int xs_probe(device_t dev) { /* * We are either operating within a PV kernel or being probed * as the child of the successfully attached xenpci device. * Thus we are in a Xen environment and there will be a XenStore. * Unconditionally return success. */ device_set_desc(dev, "XenStore"); return (BUS_PROBE_NOWILDCARD); } static void xs_attach_deferred(void *arg) { bus_generic_probe(xs.xs_dev); bus_generic_attach(xs.xs_dev); config_intrhook_disestablish(&xs.xs_attachcb); } static void xs_attach_late(void *arg, int pending) { KASSERT((pending == 1), ("xs late attach queued several times")); bus_generic_probe(xs.xs_dev); bus_generic_attach(xs.xs_dev); } /** * Attach to the XenStore. * * This routine also prepares for the probe/attach of drivers that rely * on the XenStore. */ static int xs_attach(device_t dev) { int error; /* Allow us to get device_t from softc and vice-versa. */ xs.xs_dev = dev; device_set_softc(dev, &xs); /* Initialize the interface to xenstore. */ struct proc *p; xs.initialized = false; if (xen_hvm_domain()) { xs.evtchn = hvm_get_parameter(HVM_PARAM_STORE_EVTCHN); xs.gpfn = hvm_get_parameter(HVM_PARAM_STORE_PFN); xen_store = pmap_mapdev(xs.gpfn * PAGE_SIZE, PAGE_SIZE); xs.initialized = true; } else if (xen_pv_domain()) { if (HYPERVISOR_start_info->store_evtchn == 0) { struct evtchn_alloc_unbound alloc_unbound; /* Allocate a local event channel for xenstore */ alloc_unbound.dom = DOMID_SELF; alloc_unbound.remote_dom = DOMID_SELF; error = HYPERVISOR_event_channel_op( EVTCHNOP_alloc_unbound, &alloc_unbound); if (error != 0) panic( "unable to alloc event channel for Dom0: %d", error); HYPERVISOR_start_info->store_evtchn = alloc_unbound.port; xs.evtchn = alloc_unbound.port; /* Allocate memory for the xs shared ring */ xen_store = malloc(PAGE_SIZE, M_XENSTORE, M_WAITOK | M_ZERO); } else { xs.evtchn = HYPERVISOR_start_info->store_evtchn; xs.initialized = true; } } else { panic("Unknown domain type, cannot initialize xenstore."); } TAILQ_INIT(&xs.reply_list); TAILQ_INIT(&xs.watch_events); mtx_init(&xs.ring_lock, "ring lock", NULL, MTX_DEF); mtx_init(&xs.reply_lock, "reply lock", NULL, MTX_DEF); sx_init(&xs.xenwatch_mutex, "xenwatch"); sx_init(&xs.request_mutex, "xenstore request"); sx_init(&xs.suspend_mutex, "xenstore suspend"); mtx_init(&xs.registered_watches_lock, "watches", NULL, MTX_DEF); mtx_init(&xs.watch_events_lock, "watch events", NULL, MTX_DEF); /* Initialize the shared memory rings to talk to xenstored */ error = xs_init_comms(); if (error) return (error); error = kproc_create(xenwatch_thread, NULL, &p, RFHIGHPID, 0, "xenwatch"); if (error) return (error); xs.xenwatch_pid = p->p_pid; error = kproc_create(xs_rcv_thread, NULL, NULL, RFHIGHPID, 0, "xenstore_rcv"); xs.xs_attachcb.ich_func = xs_attach_deferred; xs.xs_attachcb.ich_arg = NULL; if (xs.initialized) { config_intrhook_establish(&xs.xs_attachcb); } else { TASK_INIT(&xs.xs_late_init, 0, xs_attach_late, NULL); } return (error); } /** * Prepare for suspension of this VM by halting XenStore access after * all transactions and individual requests have completed. */ static int xs_suspend(device_t dev) { int error; /* Suspend child Xen devices. */ error = bus_generic_suspend(dev); if (error != 0) return (error); sx_xlock(&xs.suspend_mutex); sx_xlock(&xs.request_mutex); return (0); } /** * Resume XenStore operations after this VM is resumed. */ static int xs_resume(device_t dev __unused) { struct xs_watch *watch; char token[sizeof(watch) * 2 + 1]; xs_init_comms(); sx_xunlock(&xs.request_mutex); /* * No need for registered_watches_lock: the suspend_mutex * is sufficient. */ LIST_FOREACH(watch, &xs.registered_watches, list) { sprintf(token, "%lX", (long)watch); xs_watch(watch->node, token); } sx_xunlock(&xs.suspend_mutex); /* Resume child Xen devices. */ bus_generic_resume(dev); return (0); } /*-------------------- Private Device Attachment Data -----------------------*/ static device_method_t xenstore_methods[] = { /* Device interface */ DEVMETHOD(device_identify, xs_identify), DEVMETHOD(device_probe, xs_probe), DEVMETHOD(device_attach, xs_attach), DEVMETHOD(device_detach, bus_generic_detach), DEVMETHOD(device_shutdown, bus_generic_shutdown), DEVMETHOD(device_suspend, xs_suspend), DEVMETHOD(device_resume, xs_resume), /* Bus interface */ DEVMETHOD(bus_add_child, bus_generic_add_child), DEVMETHOD(bus_alloc_resource, bus_generic_alloc_resource), DEVMETHOD(bus_release_resource, bus_generic_release_resource), DEVMETHOD(bus_activate_resource, bus_generic_activate_resource), DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource), DEVMETHOD_END }; DEFINE_CLASS_0(xenstore, xenstore_driver, xenstore_methods, 0); static devclass_t xenstore_devclass; DRIVER_MODULE(xenstore, xenpv, xenstore_driver, xenstore_devclass, 0, 0); /*------------------------------- Sysctl Data --------------------------------*/ /* XXX Shouldn't the node be somewhere else? */ SYSCTL_NODE(_dev, OID_AUTO, xen, CTLFLAG_RD, NULL, "Xen"); SYSCTL_INT(_dev_xen, OID_AUTO, xsd_port, CTLFLAG_RD, &xs.evtchn, 0, ""); SYSCTL_ULONG(_dev_xen, OID_AUTO, xsd_kva, CTLFLAG_RD, (u_long *) &xen_store, 0, ""); /*-------------------------------- Public API --------------------------------*/ /*------- API comments for these methods can be found in xenstorevar.h -------*/ int xs_directory(struct xs_transaction t, const char *dir, const char *node, u_int *num, const char ***result) { struct sbuf *path; char *strings; u_int len = 0; int error; path = xs_join(dir, node); error = xs_single(t, XS_DIRECTORY, sbuf_data(path), &len, (void **)&strings); sbuf_delete(path); if (error) return (error); *result = split(strings, len, num); return (0); } int xs_exists(struct xs_transaction t, const char *dir, const char *node) { const char **d; int error, dir_n; error = xs_directory(t, dir, node, &dir_n, &d); if (error) return (0); free(d, M_XENSTORE); return (1); } int xs_read(struct xs_transaction t, const char *dir, const char *node, u_int *len, void **result) { struct sbuf *path; void *ret; int error; path = xs_join(dir, node); error = xs_single(t, XS_READ, sbuf_data(path), len, &ret); sbuf_delete(path); if (error) return (error); *result = ret; return (0); } int xs_write(struct xs_transaction t, const char *dir, const char *node, const char *string) { struct sbuf *path; struct iovec iovec[2]; int error; path = xs_join(dir, node); iovec[0].iov_base = (void *)(uintptr_t) sbuf_data(path); iovec[0].iov_len = sbuf_len(path) + 1; iovec[1].iov_base = (void *)(uintptr_t) string; iovec[1].iov_len = strlen(string); error = xs_talkv(t, XS_WRITE, iovec, 2, NULL, NULL); sbuf_delete(path); return (error); } int xs_mkdir(struct xs_transaction t, const char *dir, const char *node) { struct sbuf *path; int ret; path = xs_join(dir, node); ret = xs_single(t, XS_MKDIR, sbuf_data(path), NULL, NULL); sbuf_delete(path); return (ret); } int xs_rm(struct xs_transaction t, const char *dir, const char *node) { struct sbuf *path; int ret; path = xs_join(dir, node); ret = xs_single(t, XS_RM, sbuf_data(path), NULL, NULL); sbuf_delete(path); return (ret); } int xs_rm_tree(struct xs_transaction xbt, const char *base, const char *node) { struct xs_transaction local_xbt; struct sbuf *root_path_sbuf; struct sbuf *cur_path_sbuf; char *root_path; char *cur_path; const char **dir; int error; retry: root_path_sbuf = xs_join(base, node); cur_path_sbuf = xs_join(base, node); root_path = sbuf_data(root_path_sbuf); cur_path = sbuf_data(cur_path_sbuf); dir = NULL; local_xbt.id = 0; if (xbt.id == 0) { error = xs_transaction_start(&local_xbt); if (error != 0) goto out; xbt = local_xbt; } while (1) { u_int count; u_int i; error = xs_directory(xbt, cur_path, "", &count, &dir); if (error) goto out; for (i = 0; i < count; i++) { error = xs_rm(xbt, cur_path, dir[i]); if (error == ENOTEMPTY) { struct sbuf *push_dir; /* * Descend to clear out this sub directory. * We'll return to cur_dir once push_dir * is empty. */ push_dir = xs_join(cur_path, dir[i]); sbuf_delete(cur_path_sbuf); cur_path_sbuf = push_dir; cur_path = sbuf_data(cur_path_sbuf); break; } else if (error != 0) { goto out; } } free(dir, M_XENSTORE); dir = NULL; if (i == count) { char *last_slash; /* Directory is empty. It is now safe to remove. */ error = xs_rm(xbt, cur_path, ""); if (error != 0) goto out; if (!strcmp(cur_path, root_path)) break; /* Return to processing the parent directory. */ last_slash = strrchr(cur_path, '/'); KASSERT(last_slash != NULL, ("xs_rm_tree: mangled path %s", cur_path)); *last_slash = '\0'; } } out: sbuf_delete(cur_path_sbuf); sbuf_delete(root_path_sbuf); if (dir != NULL) free(dir, M_XENSTORE); if (local_xbt.id != 0) { int terror; terror = xs_transaction_end(local_xbt, /*abort*/error != 0); xbt.id = 0; if (terror == EAGAIN && error == 0) goto retry; } return (error); } int xs_transaction_start(struct xs_transaction *t) { char *id_str; int error; error = xs_single(XST_NIL, XS_TRANSACTION_START, "", NULL, (void **)&id_str); if (error == 0) { t->id = strtoul(id_str, NULL, 0); free(id_str, M_XENSTORE); } return (error); } int xs_transaction_end(struct xs_transaction t, int abort) { char abortstr[2]; if (abort) strcpy(abortstr, "F"); else strcpy(abortstr, "T"); return (xs_single(t, XS_TRANSACTION_END, abortstr, NULL, NULL)); } int xs_scanf(struct xs_transaction t, const char *dir, const char *node, int *scancountp, const char *fmt, ...) { va_list ap; int error, ns; char *val; error = xs_read(t, dir, node, NULL, (void **) &val); if (error) return (error); va_start(ap, fmt); ns = vsscanf(val, fmt, ap); va_end(ap); free(val, M_XENSTORE); /* Distinctive errno. */ if (ns == 0) return (ERANGE); if (scancountp) *scancountp = ns; return (0); } int xs_vprintf(struct xs_transaction t, const char *dir, const char *node, const char *fmt, va_list ap) { struct sbuf *sb; int error; sb = sbuf_new_auto(); sbuf_vprintf(sb, fmt, ap); sbuf_finish(sb); error = xs_write(t, dir, node, sbuf_data(sb)); sbuf_delete(sb); return (error); } int xs_printf(struct xs_transaction t, const char *dir, const char *node, const char *fmt, ...) { va_list ap; int error; va_start(ap, fmt); error = xs_vprintf(t, dir, node, fmt, ap); va_end(ap); return (error); } int xs_gather(struct xs_transaction t, const char *dir, ...) { va_list ap; const char *name; int error; va_start(ap, dir); error = 0; while (error == 0 && (name = va_arg(ap, char *)) != NULL) { const char *fmt = va_arg(ap, char *); void *result = va_arg(ap, void *); char *p; error = xs_read(t, dir, name, NULL, (void **) &p); if (error) break; if (fmt) { if (sscanf(p, fmt, result) == 0) error = EINVAL; free(p, M_XENSTORE); } else *(char **)result = p; } va_end(ap); return (error); } int xs_register_watch(struct xs_watch *watch) { /* Pointer in ascii is the token. */ char token[sizeof(watch) * 2 + 1]; int error; sprintf(token, "%lX", (long)watch); sx_slock(&xs.suspend_mutex); mtx_lock(&xs.registered_watches_lock); KASSERT(find_watch(token) == NULL, ("watch already registered")); LIST_INSERT_HEAD(&xs.registered_watches, watch, list); mtx_unlock(&xs.registered_watches_lock); error = xs_watch(watch->node, token); /* Ignore errors due to multiple registration. */ if (error == EEXIST) error = 0; if (error != 0) { mtx_lock(&xs.registered_watches_lock); LIST_REMOVE(watch, list); mtx_unlock(&xs.registered_watches_lock); } sx_sunlock(&xs.suspend_mutex); return (error); } void xs_unregister_watch(struct xs_watch *watch) { struct xs_stored_msg *msg, *tmp; char token[sizeof(watch) * 2 + 1]; int error; sprintf(token, "%lX", (long)watch); sx_slock(&xs.suspend_mutex); mtx_lock(&xs.registered_watches_lock); if (find_watch(token) == NULL) { mtx_unlock(&xs.registered_watches_lock); sx_sunlock(&xs.suspend_mutex); return; } LIST_REMOVE(watch, list); mtx_unlock(&xs.registered_watches_lock); error = xs_unwatch(watch->node, token); if (error) log(LOG_WARNING, "XENSTORE Failed to release watch %s: %i\n", watch->node, error); sx_sunlock(&xs.suspend_mutex); /* Cancel pending watch events. */ mtx_lock(&xs.watch_events_lock); TAILQ_FOREACH_SAFE(msg, &xs.watch_events, list, tmp) { if (msg->u.watch.handle != watch) continue; TAILQ_REMOVE(&xs.watch_events, msg, list); free(msg->u.watch.vec, M_XENSTORE); free(msg, M_XENSTORE); } mtx_unlock(&xs.watch_events_lock); /* Flush any currently-executing callback, unless we are it. :-) */ if (curproc->p_pid != xs.xenwatch_pid) { sx_xlock(&xs.xenwatch_mutex); sx_xunlock(&xs.xenwatch_mutex); } }