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/******************************************************************************
* xenbus_comms.c
*
* Low level code to talks to Xen Store: ringbuffer and event channel.
*
* Copyright (C) 2005 Rusty Russell, IBM 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/syslog.h>
#include <machine/xen/xen-os.h>
#include <xen/hypervisor.h>
#include <xen/xen_intr.h>
#include <xen/evtchn.h>
#include <xen/interface/io/xs_wire.h>
#include <xen/xenbus/xenbus_comms.h>
static unsigned int xenstore_irq;
static inline struct xenstore_domain_interface *
xenstore_domain_interface(void)
{
return (struct xenstore_domain_interface *)xen_store;
}
static void
xb_intr(void * arg __attribute__((unused)))
{
wakeup(xen_store);
}
static int
xb_check_indexes(XENSTORE_RING_IDX cons, XENSTORE_RING_IDX prod)
{
return ((prod - cons) <= XENSTORE_RING_SIZE);
}
static void *
xb_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 *
xb_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));
}
int
xb_write(const void *tdata, unsigned len, struct lock_object *lock)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
XENSTORE_RING_IDX cons, prod;
const char *data = (const char *)tdata;
int error;
while (len != 0) {
void *dst;
unsigned int avail;
while ((intf->req_prod - intf->req_cons)
== XENSTORE_RING_SIZE) {
error = _sleep(intf,
lock,
PCATCH, "xbwrite", hz/10);
if (error && error != EWOULDBLOCK)
return (error);
}
/* Read indexes, then verify. */
cons = intf->req_cons;
prod = intf->req_prod;
mb();
if (!xb_check_indexes(cons, prod)) {
intf->req_cons = intf->req_prod = 0;
return (EIO);
}
dst = xb_get_output_chunk(cons, prod, intf->req, &avail);
if (avail == 0)
continue;
if (avail > len)
avail = len;
mb();
memcpy(dst, data, avail);
data += avail;
len -= avail;
/* Other side must not see new header until data is there. */
wmb();
intf->req_prod += avail;
/* This implies mb() before other side sees interrupt. */
notify_remote_via_evtchn(xen_store_evtchn);
}
return (0);
}
int
xb_read(void *tdata, unsigned len, struct lock_object *lock)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
XENSTORE_RING_IDX cons, prod;
char *data = (char *)tdata;
int error;
while (len != 0) {
unsigned int avail;
const char *src;
while (intf->rsp_cons == intf->rsp_prod) {
error = _sleep(intf, lock,
PCATCH, "xbread", hz/10);
if (error && error != EWOULDBLOCK)
return (error);
}
/* Read indexes, then verify. */
cons = intf->rsp_cons;
prod = intf->rsp_prod;
if (!xb_check_indexes(cons, prod)) {
intf->rsp_cons = intf->rsp_prod = 0;
return (EIO);
}
src = xb_get_input_chunk(cons, prod, intf->rsp, &avail);
if (avail == 0)
continue;
if (avail > len)
avail = len;
/* We must read header before we read data. */
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;
/* Implies mb(): they will see new header. */
notify_remote_via_evtchn(xen_store_evtchn);
}
return (0);
}
/* Set up interrupt handler off store event channel. */
int
xb_init_comms(void)
{
struct xenstore_domain_interface *intf = xenstore_domain_interface();
int error;
if (intf->rsp_prod != intf->rsp_cons) {
log(LOG_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 (xenstore_irq)
unbind_from_irqhandler(xenstore_irq);
error = bind_caller_port_to_irqhandler(
xen_store_evtchn, "xenbus",
xb_intr, NULL, INTR_TYPE_NET, &xenstore_irq);
if (error) {
log(LOG_WARNING, "XENBUS request irq failed %i\n", error);
return (error);
}
return (0);
}
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