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