[RFC PATCH 15/17] block/nvme: Use per-queue AIO context

[Philippe Mathieu-Daudé]

To be able to use multiple queues on the same hardware,
we need to have each queue able to receive IRQ notifications
in the correct AIO context.
The context has to be proper to each queue, not to the block
driver. Move aio_context from BDRVNVMeState to NVMeQueuePair.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
RFC because I'm not familiar with AIO context

 block/nvme.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

diff --git a/block/nvme.c b/block/nvme.c
index ac933cafd0..0f7cc568ef 100644
--- a/block/nvme.c
+++ b/block/nvme.c
@@ -51,6 +51,7 @@ typedef struct {
 } NVMeRequest;
 
 typedef struct {
+    AioContext *aio_context;
     CoQueue     free_req_queue;
     QemuMutex   lock;
 
@@ -93,7 +94,6 @@ QEMU_BUILD_BUG_ON(offsetof(NVMeRegs, doorbells) != 0x1000);
 #define QUEUE_INDEX_IO(n)   (1 + n)
 
 typedef struct {
-    AioContext *aio_context;
     QEMUVFIOState *vfio;
     NVMeRegs *regs;
     /* The submission/completion queue pairs.
@@ -190,6 +190,7 @@ static void nvme_free_req_queue_cb(void *opaque)
 }
 
 static NVMeQueuePair *nvme_create_queue_pair(BDRVNVMeState *s,
+                                             AioContext *aio_context,
                                              int idx, int size,
                                              Error **errp)
 {
@@ -207,6 +208,7 @@ static NVMeQueuePair *nvme_create_queue_pair(BDRVNVMeState 
*s,
     if (!q->prp_list_pages) {
         goto fail;
     }
+    q->aio_context = aio_context;
     memset(q->prp_list_pages, 0, s->page_size * NVME_QUEUE_SIZE);
     qemu_mutex_init(&q->lock);
     q->index = idx;
@@ -365,7 +367,7 @@ static bool nvme_process_completion(BDRVNVMeState *s, 
NVMeQueuePair *q)
         smp_mb_release();
         *q->cq.doorbell = cpu_to_le32(q->cq.head);
         if (!qemu_co_queue_empty(&q->free_req_queue)) {
-            replay_bh_schedule_oneshot_event(s->aio_context,
+            replay_bh_schedule_oneshot_event(q->aio_context,
                                              nvme_free_req_queue_cb, q);
         }
     }
@@ -419,7 +421,6 @@ static void nvme_cmd_sync_cb(void *opaque, int ret)
 static int nvme_cmd_sync(BlockDriverState *bs, NVMeQueuePair *q,
                          NvmeCmd *cmd)
 {
-    AioContext *aio_context = bdrv_get_aio_context(bs);
     NVMeRequest *req;
     BDRVNVMeState *s = bs->opaque;
     int ret = -EINPROGRESS;
@@ -429,7 +430,7 @@ static int nvme_cmd_sync(BlockDriverState *bs, 
NVMeQueuePair *q,
     }
     nvme_submit_command(s, q, req, cmd, nvme_cmd_sync_cb, &ret);
 
-    AIO_WAIT_WHILE(aio_context, ret == -EINPROGRESS);
+    AIO_WAIT_WHILE(q->aio_context, ret == -EINPROGRESS);
     return ret;
 }
 
@@ -547,7 +548,8 @@ static void nvme_handle_event(EventNotifier *n)
     nvme_poll_queues(s);
 }
 
-static bool nvme_add_io_queue(BlockDriverState *bs, Error **errp)
+static bool nvme_add_io_queue(BlockDriverState *bs,
+                              AioContext *aio_context, Error **errp)
 {
     BDRVNVMeState *s = bs->opaque;
     int n = s->nr_queues;
@@ -555,7 +557,7 @@ static bool nvme_add_io_queue(BlockDriverState *bs, Error 
**errp)
     NvmeCmd cmd;
     int queue_size = NVME_QUEUE_SIZE;
 
-    q = nvme_create_queue_pair(s, n, queue_size, errp);
+    q = nvme_create_queue_pair(s, aio_context, n, queue_size, errp);
     if (!q) {
         return false;
     }
@@ -600,6 +602,7 @@ static int nvme_init(BlockDriverState *bs, const char 
*device, int namespace,
                      Error **errp)
 {
     BDRVNVMeState *s = bs->opaque;
+    AioContext *aio_context = bdrv_get_aio_context(bs);
     int ret;
     uint64_t cap;
     uint64_t timeout_ms;
@@ -610,7 +613,6 @@ static int nvme_init(BlockDriverState *bs, const char 
*device, int namespace,
     qemu_co_queue_init(&s->dma_flush_queue);
     s->device = g_strdup(device);
     s->nsid = namespace;
-    s->aio_context = bdrv_get_aio_context(bs);
     ret = event_notifier_init(&s->irq_notifier, 0);
     if (ret) {
         error_setg(errp, "Failed to init event notifier");
@@ -660,7 +662,7 @@ static int nvme_init(BlockDriverState *bs, const char 
*device, int namespace,
 
     /* Set up admin queue. */
     s->queues = g_new(NVMeQueuePair *, 1);
-    s->queues[QUEUE_INDEX_ADMIN] = nvme_create_queue_pair(s, 0,
+    s->queues[QUEUE_INDEX_ADMIN] = nvme_create_queue_pair(s, aio_context, 0,
                                                           NVME_QUEUE_SIZE,
                                                           errp);
     if (!s->queues[QUEUE_INDEX_ADMIN]) {
@@ -695,7 +697,7 @@ static int nvme_init(BlockDriverState *bs, const char 
*device, int namespace,
     if (ret) {
         goto out;
     }
-    aio_set_event_notifier(bdrv_get_aio_context(bs), &s->irq_notifier,
+    aio_set_event_notifier(aio_context, &s->irq_notifier,
                            false, nvme_handle_event, nvme_poll_cb);
 
     nvme_identify(bs, namespace, &local_err);
@@ -706,7 +708,7 @@ static int nvme_init(BlockDriverState *bs, const char 
*device, int namespace,
     }
 
     /* Set up command queues. */
-    if (!nvme_add_io_queue(bs, errp)) {
+    if (!nvme_add_io_queue(bs, aio_context, errp)) {
         ret = -EIO;
     }
 out:
@@ -775,11 +777,11 @@ static void nvme_close(BlockDriverState *bs)
     BDRVNVMeState *s = bs->opaque;
 
     for (i = 0; i < s->nr_queues; ++i) {
+        aio_set_event_notifier(s->queues[i]->aio_context,
+                               &s->irq_notifier, false, NULL, NULL);
         nvme_free_queue_pair(s->queues[i]);
     }
     g_free(s->queues);
-    aio_set_event_notifier(bdrv_get_aio_context(bs), &s->irq_notifier,
-                           false, NULL, NULL);
     event_notifier_cleanup(&s->irq_notifier);
     qemu_vfio_pci_unmap_bar(s->vfio, 0, (void *)s->regs, 0, NVME_BAR_SIZE);
     qemu_vfio_close(s->vfio);
@@ -992,7 +994,7 @@ static coroutine_fn int 
nvme_co_prw_aligned(BlockDriverState *bs,
         .cdw12 = cpu_to_le32(cdw12),
     };
     NVMeCoData data = {
-        .ctx = bdrv_get_aio_context(bs),
+        .ctx = ioq->aio_context,
         .ret = -EINPROGRESS,
     };
 
@@ -1101,7 +1103,7 @@ static coroutine_fn int nvme_co_flush(BlockDriverState 
*bs)
         .nsid = cpu_to_le32(s->nsid),
     };
     NVMeCoData data = {
-        .ctx = bdrv_get_aio_context(bs),
+        .ctx = ioq->aio_context,
         .ret = -EINPROGRESS,
     };
 
@@ -1142,7 +1144,7 @@ static coroutine_fn int 
nvme_co_pwrite_zeroes(BlockDriverState *bs,
     };
 
     NVMeCoData data = {
-        .ctx = bdrv_get_aio_context(bs),
+        .ctx = ioq->aio_context,
         .ret = -EINPROGRESS,
     };
 
@@ -1192,7 +1194,7 @@ static int coroutine_fn nvme_co_pdiscard(BlockDriverState 
*bs,
     };
 
     NVMeCoData data = {
-        .ctx = bdrv_get_aio_context(bs),
+        .ctx = ioq->aio_context,
         .ret = -EINPROGRESS,
     };
 
@@ -1289,7 +1291,6 @@ static void nvme_attach_aio_context(BlockDriverState *bs,
 {
     BDRVNVMeState *s = bs->opaque;
 
-    s->aio_context = new_context;
     aio_set_event_notifier(new_context, &s->irq_notifier,
                            false, nvme_handle_event, nvme_poll_cb);
 }
-- 
2.21.3