cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
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qemu-coroutine-sleep.c (2133B)

      1/*
      2 * QEMU coroutine sleep
      3 *
      4 * Copyright IBM, Corp. 2011
      5 *
      6 * Authors:
      7 *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
      8 *
      9 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
     10 * See the COPYING.LIB file in the top-level directory.
     11 *
     12 */
     13
     14#include "qemu/osdep.h"
     15#include "qemu/coroutine.h"
     16#include "qemu/coroutine_int.h"
     17#include "qemu/timer.h"
     18#include "block/aio.h"
     19
     20static const char *qemu_co_sleep_ns__scheduled = "qemu_co_sleep_ns";
     21
     22void qemu_co_sleep_wake(QemuCoSleep *w)
     23{
     24    Coroutine *co;
     25
     26    co = w->to_wake;
     27    w->to_wake = NULL;
     28    if (co) {
     29        /* Write of schedule protected by barrier write in aio_co_schedule */
     30        const char *scheduled = qatomic_cmpxchg(&co->scheduled,
     31                                                qemu_co_sleep_ns__scheduled, NULL);
     32
     33        assert(scheduled == qemu_co_sleep_ns__scheduled);
     34        aio_co_wake(co);
     35    }
     36}
     37
     38static void co_sleep_cb(void *opaque)
     39{
     40    QemuCoSleep *w = opaque;
     41    qemu_co_sleep_wake(w);
     42}
     43
     44void coroutine_fn qemu_co_sleep(QemuCoSleep *w)
     45{
     46    Coroutine *co = qemu_coroutine_self();
     47
     48    const char *scheduled = qatomic_cmpxchg(&co->scheduled, NULL,
     49                                            qemu_co_sleep_ns__scheduled);
     50    if (scheduled) {
     51        fprintf(stderr,
     52                "%s: Co-routine was already scheduled in '%s'\n",
     53                __func__, scheduled);
     54        abort();
     55    }
     56
     57    w->to_wake = co;
     58    qemu_coroutine_yield();
     59
     60    /* w->to_wake is cleared before resuming this coroutine.  */
     61    assert(w->to_wake == NULL);
     62}
     63
     64void coroutine_fn qemu_co_sleep_ns_wakeable(QemuCoSleep *w,
     65                                            QEMUClockType type, int64_t ns)
     66{
     67    AioContext *ctx = qemu_get_current_aio_context();
     68    QEMUTimer ts;
     69
     70    aio_timer_init(ctx, &ts, type, SCALE_NS, co_sleep_cb, w);
     71    timer_mod(&ts, qemu_clock_get_ns(type) + ns);
     72
     73    /*
     74     * The timer will fire in the current AiOContext, so the callback
     75     * must happen after qemu_co_sleep yields and there is no race
     76     * between timer_mod and qemu_co_sleep.
     77     */
     78    qemu_co_sleep(w);
     79    timer_del(&ts);
     80}