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81da3f2b4fa9ccbbdcd135275ee62f0817bcab26
xen/tools/libvchan/init.c
T
Marek Marczykowski-Górecki dae844977e tools/libvchan: notify server when client is connected 
Let the server know when the client is connected. Otherwise server will
notice only when client send some data.
This change does not break existing clients, as libvchan user should
handle spurious notifications anyway (for example acknowledge of remote
side reading the data).

Cc: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Replace spaces with tabs to match the file's whitespace.
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
2020-05-19 16:19:15 +01:00

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/**
* @file
* @section AUTHORS
*
* Copyright (C) 2010 Rafal Wojtczuk <rafal@invisiblethingslab.com>
*
* Authors:
* Rafal Wojtczuk <rafal@invisiblethingslab.com>
* Daniel De Graaf <dgdegra@tycho.nsa.gov>
*
* @section LICENSE
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; If not, see <http://www.gnu.org/licenses/>.
*
* @section DESCRIPTION
*
* This file contains the setup code used to establish the ring buffer.
*/
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <sys/user.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <xenstore.h>
#include <xen/xen.h>
#include <xen/sys/evtchn.h>
#include <xen/sys/gntalloc.h>
#include <xen/sys/gntdev.h>
#include <libxenvchan.h>
#ifndef PAGE_SHIFT
#define PAGE_SHIFT 12
#endif
#ifndef PAGE_SIZE
#define PAGE_SIZE 4096
#endif
#define SMALL_RING_SHIFT 10
#define LARGE_RING_SHIFT 11
#define MAX_SMALL_RING (1 << SMALL_RING_SHIFT)
#define SMALL_RING_OFFSET 1024
#define MAX_LARGE_RING (1 << LARGE_RING_SHIFT)
#define LARGE_RING_OFFSET 2048
// if you go over this size, you'll have too many grants to fit in the shared page.
#define MAX_RING_SHIFT 20
#define MAX_RING_SIZE (1 << MAX_RING_SHIFT)
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif
#define max(a,b) ((a > b) ? a : b)
static int init_gnt_srv(struct libxenvchan *ctrl, int domain)
{
int pages_left = ctrl->read.order >= PAGE_SHIFT ? 1 << (ctrl->read.order - PAGE_SHIFT) : 0;
int pages_right = ctrl->write.order >= PAGE_SHIFT ? 1 << (ctrl->write.order - PAGE_SHIFT) : 0;
uint32_t ring_ref = -1;
void *ring;
ring = xengntshr_share_page_notify(ctrl->gntshr, domain,
&ring_ref, 1, offsetof(struct vchan_interface, srv_live),
ctrl->event_port);
if (!ring)
goto out;
memset(ring, 0, PAGE_SIZE);
ctrl->ring = ring;
ctrl->read.shr = &ctrl->ring->left;
ctrl->write.shr = &ctrl->ring->right;
ctrl->ring->left_order = ctrl->read.order;
ctrl->ring->right_order = ctrl->write.order;
ctrl->ring->cli_live = 2;
ctrl->ring->srv_live = 1;
ctrl->ring->cli_notify = VCHAN_NOTIFY_WRITE;
switch (ctrl->read.order) {
case SMALL_RING_SHIFT:
ctrl->read.buffer = ((void*)ctrl->ring) + SMALL_RING_OFFSET;
break;
case LARGE_RING_SHIFT:
ctrl->read.buffer = ((void*)ctrl->ring) + LARGE_RING_OFFSET;
break;
default:
ctrl->read.buffer = xengntshr_share_pages(ctrl->gntshr, domain,
pages_left, ctrl->ring->grants, 1);
if (!ctrl->read.buffer)
goto out_ring;
}
switch (ctrl->write.order) {
case SMALL_RING_SHIFT:
ctrl->write.buffer = ((void*)ctrl->ring) + SMALL_RING_OFFSET;
break;
case LARGE_RING_SHIFT:
ctrl->write.buffer = ((void*)ctrl->ring) + LARGE_RING_OFFSET;
break;
default:
ctrl->write.buffer = xengntshr_share_pages(ctrl->gntshr, domain,
pages_right, ctrl->ring->grants + pages_left, 1);
if (!ctrl->write.buffer)
goto out_unmap_left;
}
out:
return ring_ref;
out_unmap_left:
if (pages_left)
xengntshr_unshare(ctrl->gntshr, ctrl->read.buffer, pages_left);
out_ring:
xengntshr_unshare(ctrl->gntshr, ring, 1);
ring_ref = -1;
ctrl->ring = NULL;
ctrl->write.order = ctrl->read.order = 0;
goto out;
}
static int init_gnt_cli(struct libxenvchan *ctrl, int domain, uint32_t ring_ref)
{
int rv = -1;
uint32_t *grants;
ctrl->ring = xengnttab_map_grant_ref_notify(ctrl->gnttab,
domain, ring_ref, PROT_READ|PROT_WRITE,
offsetof(struct vchan_interface, cli_live), ctrl->event_port);
if (!ctrl->ring)
goto out;
ctrl->write.order = ctrl->ring->left_order;
ctrl->read.order = ctrl->ring->right_order;
ctrl->write.shr = &ctrl->ring->left;
ctrl->read.shr = &ctrl->ring->right;
if (ctrl->write.order < SMALL_RING_SHIFT || ctrl->write.order > MAX_RING_SHIFT)
goto out_unmap_ring;
if (ctrl->read.order < SMALL_RING_SHIFT || ctrl->read.order > MAX_RING_SHIFT)
goto out_unmap_ring;
if (ctrl->read.order == ctrl->write.order && ctrl->read.order < PAGE_SHIFT)
goto out_unmap_ring;
grants = ctrl->ring->grants;
switch (ctrl->write.order) {
case SMALL_RING_SHIFT:
ctrl->write.buffer = ((void*)ctrl->ring) + SMALL_RING_OFFSET;
break;
case LARGE_RING_SHIFT:
ctrl->write.buffer = ((void*)ctrl->ring) + LARGE_RING_OFFSET;
break;
default:
{
int pages_left = 1 << (ctrl->write.order - PAGE_SHIFT);
ctrl->write.buffer = xengnttab_map_domain_grant_refs(ctrl->gnttab,
pages_left, domain, grants, PROT_READ|PROT_WRITE);
if (!ctrl->write.buffer)
goto out_unmap_ring;
grants += pages_left;
}
}
switch (ctrl->read.order) {
case SMALL_RING_SHIFT:
ctrl->read.buffer = ((void*)ctrl->ring) + SMALL_RING_OFFSET;
break;
case LARGE_RING_SHIFT:
ctrl->read.buffer = ((void*)ctrl->ring) + LARGE_RING_OFFSET;
break;
default:
{
int pages_right = 1 << (ctrl->read.order - PAGE_SHIFT);
ctrl->read.buffer = xengnttab_map_domain_grant_refs(ctrl->gnttab,
pages_right, domain, grants, PROT_READ);
if (!ctrl->read.buffer)
goto out_unmap_left;
}
}
rv = 0;
out:
return rv;
out_unmap_left:
if (ctrl->write.order >= PAGE_SHIFT)
xengnttab_unmap(ctrl->gnttab, ctrl->write.buffer,
1 << (ctrl->write.order - PAGE_SHIFT));
out_unmap_ring:
xengnttab_unmap(ctrl->gnttab, ctrl->ring, 1);
ctrl->ring = 0;
ctrl->write.order = ctrl->read.order = 0;
rv = -1;
goto out;
}
static int init_evt_srv(struct libxenvchan *ctrl, int domain,
struct xentoollog_logger *logger)
{
xenevtchn_port_or_error_t port;
ctrl->event = xenevtchn_open(logger, 0);
if (!ctrl->event)
return -1;
port = xenevtchn_bind_unbound_port(ctrl->event, domain);
if (port < 0)
goto fail;
ctrl->event_port = port;
if (xenevtchn_unmask(ctrl->event, ctrl->event_port))
goto fail;
return 0;
fail:
if (port >= 0)
xenevtchn_unbind(ctrl->event, port);
xenevtchn_close(ctrl->event);
ctrl->event = NULL;
return -1;
}
static int init_xs_srv(struct libxenvchan *ctrl, int domain, const char* xs_base, int ring_ref)
{
int ret = -1;
struct xs_handle *xs;
struct xs_permissions perms[2];
char buf[64];
char ref[16];
char* domid_str = NULL;
xs_transaction_t xs_trans = XBT_NULL;
xs = xs_domain_open();
if (!xs)
goto fail;
domid_str = xs_read(xs, 0, "domid", NULL);
if (!domid_str)
goto fail_xs_open;
// owner domain is us
perms[0].id = atoi(domid_str);
// permissions for domains not listed = none
perms[0].perms = XS_PERM_NONE;
// other domains
perms[1].id = domain;
perms[1].perms = XS_PERM_READ;
retry_transaction:
xs_trans = xs_transaction_start(xs);
if (!xs_trans)
goto fail_xs_open;
snprintf(ref, sizeof ref, "%d", ring_ref);
snprintf(buf, sizeof buf, "%s/ring-ref", xs_base);
if (!xs_write(xs, xs_trans, buf, ref, strlen(ref)))
goto fail_xs_open;
if (!xs_set_permissions(xs, xs_trans, buf, perms, 2))
goto fail_xs_open;
snprintf(ref, sizeof ref, "%d", ctrl->event_port);
snprintf(buf, sizeof buf, "%s/event-channel", xs_base);
if (!xs_write(xs, xs_trans, buf, ref, strlen(ref)))
goto fail_xs_open;
if (!xs_set_permissions(xs, xs_trans, buf, perms, 2))
goto fail_xs_open;
if (!xs_transaction_end(xs, xs_trans, 0)) {
if (errno == EAGAIN)
goto retry_transaction;
} else {
ret = 0;
}
fail_xs_open:
free(domid_str);
xs_daemon_close(xs);
fail:
return ret;
}
static int min_order(size_t siz)
{
int rv = PAGE_SHIFT;
while (siz > (1 << rv))
rv++;
return rv;
}
struct libxenvchan *libxenvchan_server_init(struct xentoollog_logger *logger,
int domain, const char* xs_path,
size_t left_min, size_t right_min)
{
struct libxenvchan *ctrl;
int ring_ref;
if (left_min > MAX_RING_SIZE || right_min > MAX_RING_SIZE)
return 0;
ctrl = malloc(sizeof(*ctrl));
if (!ctrl)
return 0;
ctrl->ring = NULL;
ctrl->event = NULL;
ctrl->is_server = 1;
ctrl->server_persist = 0;
ctrl->read.order = min_order(left_min);
ctrl->write.order = min_order(right_min);
// if we can avoid allocating extra pages by using in-page rings, do so
if (left_min <= MAX_SMALL_RING && right_min <= MAX_LARGE_RING) {
ctrl->read.order = SMALL_RING_SHIFT;
ctrl->write.order = LARGE_RING_SHIFT;
} else if (left_min <= MAX_LARGE_RING && right_min <= MAX_SMALL_RING) {
ctrl->read.order = LARGE_RING_SHIFT;
ctrl->write.order = SMALL_RING_SHIFT;
} else if (left_min <= MAX_LARGE_RING) {
ctrl->read.order = LARGE_RING_SHIFT;
} else if (right_min <= MAX_LARGE_RING) {
ctrl->write.order = LARGE_RING_SHIFT;
}
ctrl->gntshr = xengntshr_open(logger, 0);
if (!ctrl->gntshr) {
free(ctrl);
return 0;
}
if (init_evt_srv(ctrl, domain, logger))
goto out;
ring_ref = init_gnt_srv(ctrl, domain);
if (ring_ref < 0)
goto out;
if (init_xs_srv(ctrl, domain, xs_path, ring_ref))
goto out;
return ctrl;
out:
libxenvchan_close(ctrl);
return 0;
}
static int init_evt_cli(struct libxenvchan *ctrl, int domain,
struct xentoollog_logger *logger)
{
xenevtchn_port_or_error_t port;
ctrl->event = xenevtchn_open(logger, 0);
if (!ctrl->event)
return -1;
port = xenevtchn_bind_interdomain(ctrl->event,
domain, ctrl->event_port);
if (port < 0)
goto fail;
ctrl->event_port = port;
if (xenevtchn_unmask(ctrl->event, ctrl->event_port))
goto fail;
return 0;
fail:
if (port >= 0)
xenevtchn_unbind(ctrl->event, port);
xenevtchn_close(ctrl->event);
ctrl->event = NULL;
return -1;
}
struct libxenvchan *libxenvchan_client_init(struct xentoollog_logger *logger,
int domain, const char* xs_path)
{
struct libxenvchan *ctrl = malloc(sizeof(struct libxenvchan));
struct xs_handle *xs = NULL;
char buf[64];
char *ref;
int ring_ref;
unsigned int len;
if (!ctrl)
return 0;
ctrl->ring = NULL;
ctrl->event = NULL;
ctrl->gnttab = NULL;
ctrl->write.order = ctrl->read.order = 0;
ctrl->is_server = 0;
xs = xs_daemon_open();
if (!xs)
xs = xs_domain_open();
if (!xs)
goto fail;
// find xenstore entry
snprintf(buf, sizeof buf, "%s/ring-ref", xs_path);
ref = xs_read(xs, 0, buf, &len);
if (!ref)
goto fail;
ring_ref = atoi(ref);
free(ref);
if (!ring_ref)
goto fail;
snprintf(buf, sizeof buf, "%s/event-channel", xs_path);
ref = xs_read(xs, 0, buf, &len);
if (!ref)
goto fail;
ctrl->event_port = atoi(ref);
free(ref);
if (!ctrl->event_port)
goto fail;
ctrl->gnttab = xengnttab_open(logger, 0);
if (!ctrl->gnttab)
goto fail;
// set up event channel
if (init_evt_cli(ctrl, domain, logger))
goto fail;
// set up shared page(s)
if (init_gnt_cli(ctrl, domain, ring_ref))
goto fail;
ctrl->ring->cli_live = 1;
ctrl->ring->srv_notify = VCHAN_NOTIFY_WRITE;
/* wake up the server */
xenevtchn_notify(ctrl->event, ctrl->event_port);
out:
if (xs)
xs_daemon_close(xs);
return ctrl;
fail:
libxenvchan_close(ctrl);
ctrl = NULL;
goto out;
}
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