cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

qemu-co-shared-resource.c (2690B)

      1/*
      2 * Helper functionality for distributing a fixed total amount of
      3 * an abstract resource among multiple coroutines.
      4 *
      5 * Copyright (c) 2019 Virtuozzo International GmbH
      6 *
      7 * Permission is hereby granted, free of charge, to any person obtaining a copy
      8 * of this software and associated documentation files (the "Software"), to deal
      9 * in the Software without restriction, including without limitation the rights
     10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     11 * copies of the Software, and to permit persons to whom the Software is
     12 * furnished to do so, subject to the following conditions:
     13 *
     14 * The above copyright notice and this permission notice shall be included in
     15 * all copies or substantial portions of the Software.
     16 *
     17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     23 * THE SOFTWARE.
     24 */
     25
     26#include "qemu/osdep.h"
     27#include "qemu/coroutine.h"
     28#include "qemu/co-shared-resource.h"
     29
     30struct SharedResource {
     31    uint64_t total; /* Set in shres_create() and not changed anymore */
     32
     33    /* State fields protected by lock */
     34    uint64_t available;
     35    CoQueue queue;
     36
     37    QemuMutex lock;
     38};
     39
     40SharedResource *shres_create(uint64_t total)
     41{
     42    SharedResource *s = g_new0(SharedResource, 1);
     43
     44    s->total = s->available = total;
     45    qemu_co_queue_init(&s->queue);
     46    qemu_mutex_init(&s->lock);
     47
     48    return s;
     49}
     50
     51void shres_destroy(SharedResource *s)
     52{
     53    assert(s->available == s->total);
     54    qemu_mutex_destroy(&s->lock);
     55    g_free(s);
     56}
     57
     58/* Called with lock held. */
     59static bool co_try_get_from_shres_locked(SharedResource *s, uint64_t n)
     60{
     61    if (s->available >= n) {
     62        s->available -= n;
     63        return true;
     64    }
     65
     66    return false;
     67}
     68
     69bool co_try_get_from_shres(SharedResource *s, uint64_t n)
     70{
     71    QEMU_LOCK_GUARD(&s->lock);
     72    return co_try_get_from_shres_locked(s, n);
     73}
     74
     75void coroutine_fn co_get_from_shres(SharedResource *s, uint64_t n)
     76{
     77    assert(n <= s->total);
     78    QEMU_LOCK_GUARD(&s->lock);
     79    while (!co_try_get_from_shres_locked(s, n)) {
     80        qemu_co_queue_wait(&s->queue, &s->lock);
     81    }
     82}
     83
     84void coroutine_fn co_put_to_shres(SharedResource *s, uint64_t n)
     85{
     86    QEMU_LOCK_GUARD(&s->lock);
     87    assert(s->total - s->available >= n);
     88    s->available += n;
     89    qemu_co_queue_restart_all(&s->queue);
     90}