u-boot/drivers/xen/xenbus.c

558 lines
12 KiB
C
Raw Normal View History

// SPDX-License-Identifier: GPL-2.0
/*
* (C) 2006 - Cambridge University
* (C) 2020 - EPAM Systems Inc.
*
* File: xenbus.c [1]
* Author: Steven Smith (sos22@cam.ac.uk)
* Changes: Grzegorz Milos (gm281@cam.ac.uk)
* Changes: John D. Ramsdell
*
* Date: Jun 2006, changes Aug 2006
*
* Description: Minimal implementation of xenbus
*
* [1] - http://xenbits.xen.org/gitweb/?p=mini-os.git;a=summary
*/
#include <common.h>
#include <log.h>
#include <asm/armv8/mmu.h>
#include <asm/io.h>
#include <asm/xen/system.h>
#include <linux/bug.h>
#include <linux/compat.h>
#include <xen/events.h>
#include <xen/hvm.h>
#include <xen/xenbus.h>
#include <xen/interface/io/xs_wire.h>
#define map_frame_virt(v) (v << PAGE_SHIFT)
#define SCNd16 "d"
/* Wait for reply time out, ms */
#define WAIT_XENBUS_TO_MS 5000
/* Polling time out, ms */
#define WAIT_XENBUS_POLL_TO_MS 1
static struct xenstore_domain_interface *xenstore_buf;
static char *errmsg(struct xsd_sockmsg *rep);
u32 xenbus_evtchn;
struct write_req {
const void *data;
unsigned int len;
};
static void memcpy_from_ring(const void *r, void *d, int off, int len)
{
int c1, c2;
const char *ring = r;
char *dest = d;
c1 = min(len, XENSTORE_RING_SIZE - off);
c2 = len - c1;
memcpy(dest, ring + off, c1);
memcpy(dest + c1, ring, c2);
}
/**
* xenbus_get_reply() - Receive reply from xenbus
* @req_reply: reply message structure
*
* Wait for reply message event from the ring and copy received message
* to input xsd_sockmsg structure. Repeat until full reply is
* proceeded.
*
* Return: false - timeout
* true - reply is received
*/
static bool xenbus_get_reply(struct xsd_sockmsg **req_reply)
{
struct xsd_sockmsg msg;
unsigned int prod = xenstore_buf->rsp_prod;
again:
if (!wait_event_timeout(NULL, prod != xenstore_buf->rsp_prod,
WAIT_XENBUS_TO_MS)) {
printk("%s: wait_event timeout\n", __func__);
return false;
}
prod = xenstore_buf->rsp_prod;
if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < sizeof(msg))
goto again;
rmb();
memcpy_from_ring(xenstore_buf->rsp, &msg,
MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
sizeof(msg));
if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < sizeof(msg) + msg.len)
goto again;
/* We do not support and expect any Xen bus wathes. */
BUG_ON(msg.type == XS_WATCH_EVENT);
*req_reply = malloc(sizeof(msg) + msg.len);
memcpy_from_ring(xenstore_buf->rsp, *req_reply,
MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
msg.len + sizeof(msg));
mb();
xenstore_buf->rsp_cons += msg.len + sizeof(msg);
wmb();
notify_remote_via_evtchn(xenbus_evtchn);
return true;
}
char *xenbus_switch_state(xenbus_transaction_t xbt, const char *path,
XenbusState state)
{
char *current_state;
char *msg = NULL;
char *msg2 = NULL;
char value[2];
XenbusState rs;
int xbt_flag = 0;
int retry = 0;
do {
if (xbt == XBT_NIL) {
msg = xenbus_transaction_start(&xbt);
if (msg)
goto exit;
xbt_flag = 1;
}
msg = xenbus_read(xbt, path, &current_state);
if (msg)
goto exit;
rs = (XenbusState)(current_state[0] - '0');
free(current_state);
if (rs == state) {
msg = NULL;
goto exit;
}
snprintf(value, 2, "%d", state);
msg = xenbus_write(xbt, path, value);
exit:
if (xbt_flag) {
msg2 = xenbus_transaction_end(xbt, 0, &retry);
xbt = XBT_NIL;
}
if (msg == NULL && msg2 != NULL)
msg = msg2;
else
free(msg2);
} while (retry);
return msg;
}
char *xenbus_wait_for_state_change(const char *path, XenbusState *state)
{
for (;;) {
char *res, *msg;
XenbusState rs;
msg = xenbus_read(XBT_NIL, path, &res);
if (msg)
return msg;
rs = (XenbusState)(res[0] - 48);
free(res);
if (rs == *state) {
wait_event_timeout(NULL, false, WAIT_XENBUS_POLL_TO_MS);
} else {
*state = rs;
break;
}
}
return NULL;
}
/* Send data to xenbus. This can block. All of the requests are seen
* by xenbus as if sent atomically. The header is added
* automatically, using type %type, req_id %req_id, and trans_id
* %trans_id.
*/
static void xb_write(int type, int req_id, xenbus_transaction_t trans_id,
const struct write_req *req, int nr_reqs)
{
XENSTORE_RING_IDX prod;
int r;
int len = 0;
const struct write_req *cur_req;
int req_off;
int total_off;
int this_chunk;
struct xsd_sockmsg m = {
.type = type,
.req_id = req_id,
.tx_id = trans_id
};
struct write_req header_req = {
&m,
sizeof(m)
};
for (r = 0; r < nr_reqs; r++)
len += req[r].len;
m.len = len;
len += sizeof(m);
cur_req = &header_req;
BUG_ON(len > XENSTORE_RING_SIZE);
prod = xenstore_buf->req_prod;
/* We are running synchronously, so it is a bug if we do not
* have enough room to send a message: please note that a message
* can occupy multiple slots in the ring buffer.
*/
BUG_ON(prod + len - xenstore_buf->req_cons > XENSTORE_RING_SIZE);
total_off = 0;
req_off = 0;
while (total_off < len) {
this_chunk = min(cur_req->len - req_off,
XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod));
memcpy((char *)xenstore_buf->req + MASK_XENSTORE_IDX(prod),
(char *)cur_req->data + req_off, this_chunk);
prod += this_chunk;
req_off += this_chunk;
total_off += this_chunk;
if (req_off == cur_req->len) {
req_off = 0;
if (cur_req == &header_req)
cur_req = req;
else
cur_req++;
}
}
BUG_ON(req_off != 0);
BUG_ON(total_off != len);
BUG_ON(prod > xenstore_buf->req_cons + XENSTORE_RING_SIZE);
/* Remote must see entire message before updating indexes */
wmb();
xenstore_buf->req_prod += len;
/* Send evtchn to notify remote */
notify_remote_via_evtchn(xenbus_evtchn);
}
/* Send a message to xenbus, in the same fashion as xb_write, and
* block waiting for a reply. The reply is malloced and should be
* freed by the caller.
*/
struct xsd_sockmsg *xenbus_msg_reply(int type,
xenbus_transaction_t trans,
struct write_req *io,
int nr_reqs)
{
struct xsd_sockmsg *rep;
/* We do not use request identifier which is echoed in daemon's response. */
xb_write(type, 0, trans, io, nr_reqs);
/* Now wait for the message to arrive. */
if (!xenbus_get_reply(&rep))
return NULL;
return rep;
}
static char *errmsg(struct xsd_sockmsg *rep)
{
char *res;
if (!rep) {
char msg[] = "No reply";
size_t len = strlen(msg) + 1;
return memcpy(malloc(len), msg, len);
}
if (rep->type != XS_ERROR)
return NULL;
res = malloc(rep->len + 1);
memcpy(res, rep + 1, rep->len);
res[rep->len] = 0;
free(rep);
return res;
}
/* List the contents of a directory. Returns a malloc()ed array of
* pointers to malloc()ed strings. The array is NULL terminated. May
* block.
*/
char *xenbus_ls(xenbus_transaction_t xbt, const char *pre, char ***contents)
{
struct xsd_sockmsg *reply, *repmsg;
struct write_req req[] = { { pre, strlen(pre) + 1 } };
int nr_elems, x, i;
char **res, *msg;
repmsg = xenbus_msg_reply(XS_DIRECTORY, xbt, req, ARRAY_SIZE(req));
msg = errmsg(repmsg);
if (msg) {
*contents = NULL;
return msg;
}
reply = repmsg + 1;
for (x = nr_elems = 0; x < repmsg->len; x++)
nr_elems += (((char *)reply)[x] == 0);
res = malloc(sizeof(res[0]) * (nr_elems + 1));
for (x = i = 0; i < nr_elems; i++) {
int l = strlen((char *)reply + x);
res[i] = malloc(l + 1);
memcpy(res[i], (char *)reply + x, l + 1);
x += l + 1;
}
res[i] = NULL;
free(repmsg);
*contents = res;
return NULL;
}
char *xenbus_read(xenbus_transaction_t xbt, const char *path, char **value)
{
struct write_req req[] = { {path, strlen(path) + 1} };
struct xsd_sockmsg *rep;
char *res, *msg;
rep = xenbus_msg_reply(XS_READ, xbt, req, ARRAY_SIZE(req));
msg = errmsg(rep);
if (msg) {
*value = NULL;
return msg;
}
res = malloc(rep->len + 1);
memcpy(res, rep + 1, rep->len);
res[rep->len] = 0;
free(rep);
*value = res;
return NULL;
}
char *xenbus_write(xenbus_transaction_t xbt, const char *path,
const char *value)
{
struct write_req req[] = {
{path, strlen(path) + 1},
{value, strlen(value)},
};
struct xsd_sockmsg *rep;
char *msg;
rep = xenbus_msg_reply(XS_WRITE, xbt, req, ARRAY_SIZE(req));
msg = errmsg(rep);
if (msg)
return msg;
free(rep);
return NULL;
}
char *xenbus_rm(xenbus_transaction_t xbt, const char *path)
{
struct write_req req[] = { {path, strlen(path) + 1} };
struct xsd_sockmsg *rep;
char *msg;
rep = xenbus_msg_reply(XS_RM, xbt, req, ARRAY_SIZE(req));
msg = errmsg(rep);
if (msg)
return msg;
free(rep);
return NULL;
}
char *xenbus_get_perms(xenbus_transaction_t xbt, const char *path, char **value)
{
struct write_req req[] = { {path, strlen(path) + 1} };
struct xsd_sockmsg *rep;
char *res, *msg;
rep = xenbus_msg_reply(XS_GET_PERMS, xbt, req, ARRAY_SIZE(req));
msg = errmsg(rep);
if (msg) {
*value = NULL;
return msg;
}
res = malloc(rep->len + 1);
memcpy(res, rep + 1, rep->len);
res[rep->len] = 0;
free(rep);
*value = res;
return NULL;
}
#define PERM_MAX_SIZE 32
char *xenbus_set_perms(xenbus_transaction_t xbt, const char *path,
domid_t dom, char perm)
{
char value[PERM_MAX_SIZE];
struct write_req req[] = {
{path, strlen(path) + 1},
{value, 0},
};
struct xsd_sockmsg *rep;
char *msg;
snprintf(value, PERM_MAX_SIZE, "%c%hu", perm, dom);
req[1].len = strlen(value) + 1;
rep = xenbus_msg_reply(XS_SET_PERMS, xbt, req, ARRAY_SIZE(req));
msg = errmsg(rep);
if (msg)
return msg;
free(rep);
return NULL;
}
char *xenbus_transaction_start(xenbus_transaction_t *xbt)
{
/* Xenstored becomes angry if you send a length 0 message, so just
* shove a nul terminator on the end
*/
struct write_req req = { "", 1};
struct xsd_sockmsg *rep;
char *err;
rep = xenbus_msg_reply(XS_TRANSACTION_START, 0, &req, 1);
err = errmsg(rep);
if (err)
return err;
sscanf((char *)(rep + 1), "%lu", xbt);
free(rep);
return NULL;
}
char *xenbus_transaction_end(xenbus_transaction_t t, int abort, int *retry)
{
struct xsd_sockmsg *rep;
struct write_req req;
char *err;
*retry = 0;
req.data = abort ? "F" : "T";
req.len = 2;
rep = xenbus_msg_reply(XS_TRANSACTION_END, t, &req, 1);
err = errmsg(rep);
if (err) {
if (!strcmp(err, "EAGAIN")) {
*retry = 1;
free(err);
return NULL;
} else {
return err;
}
}
free(rep);
return NULL;
}
int xenbus_read_integer(const char *path)
{
char *res, *buf;
int t;
res = xenbus_read(XBT_NIL, path, &buf);
if (res) {
printk("Failed to read %s.\n", path);
free(res);
return -1;
}
sscanf(buf, "%d", &t);
free(buf);
return t;
}
int xenbus_read_uuid(const char *path, unsigned char uuid[16])
{
char *res, *buf;
res = xenbus_read(XBT_NIL, path, &buf);
if (res) {
printk("Failed to read %s.\n", path);
free(res);
return 0;
}
if (strlen(buf) != ((2 * 16) + 4) /* 16 hex bytes and 4 hyphens */
|| sscanf(buf,
"%2hhx%2hhx%2hhx%2hhx-"
"%2hhx%2hhx-"
"%2hhx%2hhx-"
"%2hhx%2hhx-"
"%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx",
uuid, uuid + 1, uuid + 2, uuid + 3,
uuid + 4, uuid + 5, uuid + 6, uuid + 7,
uuid + 8, uuid + 9, uuid + 10, uuid + 11,
uuid + 12, uuid + 13, uuid + 14, uuid + 15) != 16) {
printk("Xenbus path %s value %s is not a uuid!\n", path, buf);
free(buf);
return 0;
}
free(buf);
return 1;
}
char *xenbus_printf(xenbus_transaction_t xbt,
const char *node, const char *path,
const char *fmt, ...)
{
#define BUFFER_SIZE 256
char fullpath[BUFFER_SIZE];
char val[BUFFER_SIZE];
va_list args;
BUG_ON(strlen(node) + strlen(path) + 1 >= BUFFER_SIZE);
sprintf(fullpath, "%s/%s", node, path);
va_start(args, fmt);
vsprintf(val, fmt, args);
va_end(args);
return xenbus_write(xbt, fullpath, val);
}
domid_t xenbus_get_self_id(void)
{
char *dom_id;
domid_t ret;
BUG_ON(xenbus_read(XBT_NIL, "domid", &dom_id));
sscanf(dom_id, "%"SCNd16, &ret);
return ret;
}
void init_xenbus(void)
{
u64 v;
debug("%s\n", __func__);
if (hvm_get_parameter(HVM_PARAM_STORE_EVTCHN, &v))
BUG();
xenbus_evtchn = v;
if (hvm_get_parameter(HVM_PARAM_STORE_PFN, &v))
BUG();
xenstore_buf = (struct xenstore_domain_interface *)map_frame_virt(v);
}
void fini_xenbus(void)
{
debug("%s\n", __func__);
}