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Diffstat (limited to 'drivers/xen/xenbus/xenbus_comms.c')
-rw-r--r--drivers/xen/xenbus/xenbus_comms.c233
1 files changed, 233 insertions, 0 deletions
diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
new file mode 100644
index 00000000000..6efbe3f29ca
--- /dev/null
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -0,0 +1,233 @@
+/******************************************************************************
+ * xenbus_comms.c
+ *
+ * Low level code to talks to Xen Store: ringbuffer and event channel.
+ *
+ * Copyright (C) 2005 Rusty Russell, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when 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 <linux/wait.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <xen/xenbus.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/events.h>
+#include <xen/page.h>
+#include "xenbus_comms.h"
+
+static int xenbus_irq;
+
+static DECLARE_WORK(probe_work, xenbus_probe);
+
+static DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
+
+static irqreturn_t wake_waiting(int irq, void *unused)
+{
+ if (unlikely(xenstored_ready == 0)) {
+ xenstored_ready = 1;
+ schedule_work(&probe_work);
+ }
+
+ wake_up(&xb_waitq);
+ return IRQ_HANDLED;
+}
+
+static int check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod)
+{
+ return ((prod - cons) <= XENSTORE_RING_SIZE);
+}
+
+static void *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);
+}
+
+static const void *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);
+}
+
+/**
+ * xb_write - low level write
+ * @data: buffer to send
+ * @len: length of buffer
+ *
+ * Returns 0 on success, error otherwise.
+ */
+int xb_write(const void *data, unsigned len)
+{
+ struct xenstore_domain_interface *intf = xen_store_interface;
+ XENSTORE_RING_IDX cons, prod;
+ int rc;
+
+ while (len != 0) {
+ void *dst;
+ unsigned int avail;
+
+ rc = wait_event_interruptible(
+ xb_waitq,
+ (intf->req_prod - intf->req_cons) !=
+ XENSTORE_RING_SIZE);
+ if (rc < 0)
+ return rc;
+
+ /* Read indexes, then verify. */
+ cons = intf->req_cons;
+ prod = intf->req_prod;
+ if (!check_indexes(cons, prod)) {
+ intf->req_cons = intf->req_prod = 0;
+ return -EIO;
+ }
+
+ dst = get_output_chunk(cons, prod, intf->req, &avail);
+ if (avail == 0)
+ continue;
+ if (avail > len)
+ avail = len;
+
+ /* Must write data /after/ reading the consumer index. */
+ mb();
+
+ memcpy(dst, data, avail);
+ data += avail;
+ len -= avail;
+
+ /* Other side must not see new producer until data is there. */
+ wmb();
+ intf->req_prod += avail;
+
+ /* Implies mb(): other side will see the updated producer. */
+ notify_remote_via_evtchn(xen_store_evtchn);
+ }
+
+ return 0;
+}
+
+int xb_data_to_read(void)
+{
+ struct xenstore_domain_interface *intf = xen_store_interface;
+ return (intf->rsp_cons != intf->rsp_prod);
+}
+
+int xb_wait_for_data_to_read(void)
+{
+ return wait_event_interruptible(xb_waitq, xb_data_to_read());
+}
+
+int xb_read(void *data, unsigned len)
+{
+ struct xenstore_domain_interface *intf = xen_store_interface;
+ XENSTORE_RING_IDX cons, prod;
+ int rc;
+
+ while (len != 0) {
+ unsigned int avail;
+ const char *src;
+
+ rc = xb_wait_for_data_to_read();
+ if (rc < 0)
+ return rc;
+
+ /* Read indexes, then verify. */
+ cons = intf->rsp_cons;
+ prod = intf->rsp_prod;
+ if (!check_indexes(cons, prod)) {
+ intf->rsp_cons = intf->rsp_prod = 0;
+ return -EIO;
+ }
+
+ src = get_input_chunk(cons, prod, intf->rsp, &avail);
+ if (avail == 0)
+ continue;
+ if (avail > len)
+ avail = len;
+
+ /* Must read data /after/ reading the producer index. */
+ rmb();
+
+ memcpy(data, src, avail);
+ data += avail;
+ len -= avail;
+
+ /* Other side must not see free space until we've copied out */
+ mb();
+ intf->rsp_cons += avail;
+
+ pr_debug("Finished read of %i bytes (%i to go)\n", avail, len);
+
+ /* Implies mb(): other side will see the updated consumer. */
+ notify_remote_via_evtchn(xen_store_evtchn);
+ }
+
+ return 0;
+}
+
+/**
+ * xb_init_comms - Set up interrupt handler off store event channel.
+ */
+int xb_init_comms(void)
+{
+ struct xenstore_domain_interface *intf = xen_store_interface;
+ int err;
+
+ if (intf->req_prod != intf->req_cons)
+ printk(KERN_ERR "XENBUS request ring is not quiescent "
+ "(%08x:%08x)!\n", intf->req_cons, intf->req_prod);
+
+ if (intf->rsp_prod != intf->rsp_cons) {
+ printk(KERN_WARNING "XENBUS response ring is not quiescent "
+ "(%08x:%08x): fixing up\n",
+ intf->rsp_cons, intf->rsp_prod);
+ intf->rsp_cons = intf->rsp_prod;
+ }
+
+ if (xenbus_irq)
+ unbind_from_irqhandler(xenbus_irq, &xb_waitq);
+
+ err = bind_evtchn_to_irqhandler(
+ xen_store_evtchn, wake_waiting,
+ 0, "xenbus", &xb_waitq);
+ if (err <= 0) {
+ printk(KERN_ERR "XENBUS request irq failed %i\n", err);
+ return err;
+ }
+
+ xenbus_irq = err;
+
+ return 0;
+}