Add qemu 2.4.0

Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>

1 files changed, 337 insertions, 0 deletions

diff --git a/qemu/block/linux-aio.c b/qemu/block/linux-aio.c
new file mode 100644
index 000000000..c991443c5
--- /dev/null
+++ b/qemu/block/linux-aio.c
@@ -0,0 +1,337 @@
+/*
+ * Linux native AIO support.
+ *
+ * Copyright (C) 2009 IBM, Corp.
+ * Copyright (C) 2009 Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+#include "qemu-common.h"
+#include "block/aio.h"
+#include "qemu/queue.h"
+#include "block/raw-aio.h"
+#include "qemu/event_notifier.h"
+
+#include <libaio.h>
+
+/*
+ * Queue size (per-device).
+ *
+ * XXX: eventually we need to communicate this to the guest and/or make it
+ *      tunable by the guest.  If we get more outstanding requests at a time
+ *      than this we will get EAGAIN from io_submit which is communicated to
+ *      the guest as an I/O error.
+ */
+#define MAX_EVENTS 128
+
+#define MAX_QUEUED_IO  128
+
+struct qemu_laiocb {
+    BlockAIOCB common;
+    struct qemu_laio_state *ctx;
+    struct iocb iocb;
+    ssize_t ret;
+    size_t nbytes;
+    QEMUIOVector *qiov;
+    bool is_read;
+    QSIMPLEQ_ENTRY(qemu_laiocb) next;
+};
+
+typedef struct {
+    int plugged;
+    unsigned int n;
+    bool blocked;
+    QSIMPLEQ_HEAD(, qemu_laiocb) pending;
+} LaioQueue;
+
+struct qemu_laio_state {
+    io_context_t ctx;
+    EventNotifier e;
+
+    /* io queue for submit at batch */
+    LaioQueue io_q;
+
+    /* I/O completion processing */
+    QEMUBH *completion_bh;
+    struct io_event events[MAX_EVENTS];
+    int event_idx;
+    int event_max;
+};
+
+static void ioq_submit(struct qemu_laio_state *s);
+
+static inline ssize_t io_event_ret(struct io_event *ev)
+{
+    return (ssize_t)(((uint64_t)ev->res2 << 32) | ev->res);
+}
+
+/*
+ * Completes an AIO request (calls the callback and frees the ACB).
+ */
+static void qemu_laio_process_completion(struct qemu_laio_state *s,
+    struct qemu_laiocb *laiocb)
+{
+    int ret;
+
+    ret = laiocb->ret;
+    if (ret != -ECANCELED) {
+        if (ret == laiocb->nbytes) {
+            ret = 0;
+        } else if (ret >= 0) {
+            /* Short reads mean EOF, pad with zeros. */
+            if (laiocb->is_read) {
+                qemu_iovec_memset(laiocb->qiov, ret, 0,
+                    laiocb->qiov->size - ret);
+            } else {
+                ret = -EINVAL;
+            }
+        }
+    }
+    laiocb->common.cb(laiocb->common.opaque, ret);
+
+    qemu_aio_unref(laiocb);
+}
+
+/* The completion BH fetches completed I/O requests and invokes their
+ * callbacks.
+ *
+ * The function is somewhat tricky because it supports nested event loops, for
+ * example when a request callback invokes aio_poll().  In order to do this,
+ * the completion events array and index are kept in qemu_laio_state.  The BH
+ * reschedules itself as long as there are completions pending so it will
+ * either be called again in a nested event loop or will be called after all
+ * events have been completed.  When there are no events left to complete, the
+ * BH returns without rescheduling.
+ */
+static void qemu_laio_completion_bh(void *opaque)
+{
+    struct qemu_laio_state *s = opaque;
+
+    /* Fetch more completion events when empty */
+    if (s->event_idx == s->event_max) {
+        do {
+            struct timespec ts = { 0 };
+            s->event_max = io_getevents(s->ctx, MAX_EVENTS, MAX_EVENTS,
+                                        s->events, &ts);
+        } while (s->event_max == -EINTR);
+
+        s->event_idx = 0;
+        if (s->event_max <= 0) {
+            s->event_max = 0;
+            return; /* no more events */
+        }
+    }
+
+    /* Reschedule so nested event loops see currently pending completions */
+    qemu_bh_schedule(s->completion_bh);
+
+    /* Process completion events */
+    while (s->event_idx < s->event_max) {
+        struct iocb *iocb = s->events[s->event_idx].obj;
+        struct qemu_laiocb *laiocb =
+                container_of(iocb, struct qemu_laiocb, iocb);
+
+        laiocb->ret = io_event_ret(&s->events[s->event_idx]);
+        s->event_idx++;
+
+        qemu_laio_process_completion(s, laiocb);
+    }
+
+    if (!s->io_q.plugged && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+        ioq_submit(s);
+    }
+}
+
+static void qemu_laio_completion_cb(EventNotifier *e)
+{
+    struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
+
+    if (event_notifier_test_and_clear(&s->e)) {
+        qemu_bh_schedule(s->completion_bh);
+    }
+}
+
+static void laio_cancel(BlockAIOCB *blockacb)
+{
+    struct qemu_laiocb *laiocb = (struct qemu_laiocb *)blockacb;
+    struct io_event event;
+    int ret;
+
+    if (laiocb->ret != -EINPROGRESS) {
+        return;
+    }
+    ret = io_cancel(laiocb->ctx->ctx, &laiocb->iocb, &event);
+    laiocb->ret = -ECANCELED;
+    if (ret != 0) {
+        /* iocb is not cancelled, cb will be called by the event loop later */
+        return;
+    }
+
+    laiocb->common.cb(laiocb->common.opaque, laiocb->ret);
+}
+
+static const AIOCBInfo laio_aiocb_info = {
+    .aiocb_size         = sizeof(struct qemu_laiocb),
+    .cancel_async       = laio_cancel,
+};
+
+static void ioq_init(LaioQueue *io_q)
+{
+    QSIMPLEQ_INIT(&io_q->pending);
+    io_q->plugged = 0;
+    io_q->n = 0;
+    io_q->blocked = false;
+}
+
+static void ioq_submit(struct qemu_laio_state *s)
+{
+    int ret, len;
+    struct qemu_laiocb *aiocb;
+    struct iocb *iocbs[MAX_QUEUED_IO];
+    QSIMPLEQ_HEAD(, qemu_laiocb) completed;
+
+    do {
+        len = 0;
+        QSIMPLEQ_FOREACH(aiocb, &s->io_q.pending, next) {
+            iocbs[len++] = &aiocb->iocb;
+            if (len == MAX_QUEUED_IO) {
+                break;
+            }
+        }
+
+        ret = io_submit(s->ctx, len, iocbs);
+        if (ret == -EAGAIN) {
+            break;
+        }
+        if (ret < 0) {
+            abort();
+        }
+
+        s->io_q.n -= ret;
+        aiocb = container_of(iocbs[ret - 1], struct qemu_laiocb, iocb);
+        QSIMPLEQ_SPLIT_AFTER(&s->io_q.pending, aiocb, next, &completed);
+    } while (ret == len && !QSIMPLEQ_EMPTY(&s->io_q.pending));
+    s->io_q.blocked = (s->io_q.n > 0);
+}
+
+void laio_io_plug(BlockDriverState *bs, void *aio_ctx)
+{
+    struct qemu_laio_state *s = aio_ctx;
+
+    s->io_q.plugged++;
+}
+
+void laio_io_unplug(BlockDriverState *bs, void *aio_ctx, bool unplug)
+{
+    struct qemu_laio_state *s = aio_ctx;
+
+    assert(s->io_q.plugged > 0 || !unplug);
+
+    if (unplug && --s->io_q.plugged > 0) {
+        return;
+    }
+
+    if (!s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+        ioq_submit(s);
+    }
+}
+
+BlockAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockCompletionFunc *cb, void *opaque, int type)
+{
+    struct qemu_laio_state *s = aio_ctx;
+    struct qemu_laiocb *laiocb;
+    struct iocb *iocbs;
+    off_t offset = sector_num * 512;
+
+    laiocb = qemu_aio_get(&laio_aiocb_info, bs, cb, opaque);
+    laiocb->nbytes = nb_sectors * 512;
+    laiocb->ctx = s;
+    laiocb->ret = -EINPROGRESS;
+    laiocb->is_read = (type == QEMU_AIO_READ);
+    laiocb->qiov = qiov;
+
+    iocbs = &laiocb->iocb;
+
+    switch (type) {
+    case QEMU_AIO_WRITE:
+        io_prep_pwritev(iocbs, fd, qiov->iov, qiov->niov, offset);
+	break;
+    case QEMU_AIO_READ:
+        io_prep_preadv(iocbs, fd, qiov->iov, qiov->niov, offset);
+	break;
+    /* Currently Linux kernel does not support other operations */
+    default:
+        fprintf(stderr, "%s: invalid AIO request type 0x%x.\n",
+                        __func__, type);
+        goto out_free_aiocb;
+    }
+    io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e));
+
+    QSIMPLEQ_INSERT_TAIL(&s->io_q.pending, laiocb, next);
+    s->io_q.n++;
+    if (!s->io_q.blocked &&
+        (!s->io_q.plugged || s->io_q.n >= MAX_QUEUED_IO)) {
+        ioq_submit(s);
+    }
+    return &laiocb->common;
+
+out_free_aiocb:
+    qemu_aio_unref(laiocb);
+    return NULL;
+}
+
+void laio_detach_aio_context(void *s_, AioContext *old_context)
+{
+    struct qemu_laio_state *s = s_;
+
+    aio_set_event_notifier(old_context, &s->e, NULL);
+    qemu_bh_delete(s->completion_bh);
+}
+
+void laio_attach_aio_context(void *s_, AioContext *new_context)
+{
+    struct qemu_laio_state *s = s_;
+
+    s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
+    aio_set_event_notifier(new_context, &s->e, qemu_laio_completion_cb);
+}
+
+void *laio_init(void)
+{
+    struct qemu_laio_state *s;
+
+    s = g_malloc0(sizeof(*s));
+    if (event_notifier_init(&s->e, false) < 0) {
+        goto out_free_state;
+    }
+
+    if (io_setup(MAX_EVENTS, &s->ctx) != 0) {
+        goto out_close_efd;
+    }
+
+    ioq_init(&s->io_q);
+
+    return s;
+
+out_close_efd:
+    event_notifier_cleanup(&s->e);
+out_free_state:
+    g_free(s);
+    return NULL;
+}
+
+void laio_cleanup(void *s_)
+{
+    struct qemu_laio_state *s = s_;
+
+    event_notifier_cleanup(&s->e);
+
+    if (io_destroy(s->ctx) != 0) {
+        fprintf(stderr, "%s: destroy AIO context %p failed\n",
+                        __func__, &s->ctx);
+    }
+    g_free(s);
+}