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qemu-kvm/kvm-virtio-blk-add-iothread...

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From 733fc13f65286c849ad6618be89df450f8bc5f7e Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Wed, 20 Dec 2023 08:47:55 -0500
Subject: [PATCH 09/22] virtio-blk: add iothread-vq-mapping parameter
RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
RH-MergeRequest: 219: virtio-blk: add iothread-vq-mapping parameter
RH-Jira: RHEL-17369 RHEL-20764 RHEL-7356
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Hanna Czenczek <hreitz@redhat.com>
RH-Commit: [5/17] c371fe62376c4eb54da88272a5966cec28404224 (stefanha/centos-stream-qemu-kvm)
Add the iothread-vq-mapping parameter to assign virtqueues to IOThreads.
Store the vq:AioContext mapping in the new struct
VirtIOBlockDataPlane->vq_aio_context[] field and refactor the code to
use the per-vq AioContext instead of the BlockDriverState's AioContext.
Reimplement --device virtio-blk-pci,iothread= and non-IOThread mode by
assigning all virtqueues to the IOThread and main loop's AioContext in
vq_aio_context[], respectively.
The comment in struct VirtIOBlockDataPlane about EventNotifiers is
stale. Remove it.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20231220134755.814917-5-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit b6948ab01df068bef591868c22d1f873d2d05cde)
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/block/dataplane/virtio-blk.c | 155 ++++++++++++++++++++++++--------
hw/block/dataplane/virtio-blk.h | 3 +
hw/block/virtio-blk.c | 92 ++++++++++++++++---
include/hw/virtio/virtio-blk.h | 2 +
4 files changed, 202 insertions(+), 50 deletions(-)
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 7bbbd981ad..6debd4401e 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -32,13 +32,11 @@ struct VirtIOBlockDataPlane {
VirtIOBlkConf *conf;
VirtIODevice *vdev;
- /* Note that these EventNotifiers are assigned by value. This is
- * fine as long as you do not call event_notifier_cleanup on them
- * (because you don't own the file descriptor or handle; you just
- * use it).
+ /*
+ * The AioContext for each virtqueue. The BlockDriverState will use the
+ * first element as its AioContext.
*/
- IOThread *iothread;
- AioContext *ctx;
+ AioContext **vq_aio_context;
};
/* Raise an interrupt to signal guest, if necessary */
@@ -47,6 +45,45 @@ void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq)
virtio_notify_irqfd(s->vdev, vq);
}
+/* Generate vq:AioContext mappings from a validated iothread-vq-mapping list */
+static void
+apply_vq_mapping(IOThreadVirtQueueMappingList *iothread_vq_mapping_list,
+ AioContext **vq_aio_context, uint16_t num_queues)
+{
+ IOThreadVirtQueueMappingList *node;
+ size_t num_iothreads = 0;
+ size_t cur_iothread = 0;
+
+ for (node = iothread_vq_mapping_list; node; node = node->next) {
+ num_iothreads++;
+ }
+
+ for (node = iothread_vq_mapping_list; node; node = node->next) {
+ IOThread *iothread = iothread_by_id(node->value->iothread);
+ AioContext *ctx = iothread_get_aio_context(iothread);
+
+ /* Released in virtio_blk_data_plane_destroy() */
+ object_ref(OBJECT(iothread));
+
+ if (node->value->vqs) {
+ uint16List *vq;
+
+ /* Explicit vq:IOThread assignment */
+ for (vq = node->value->vqs; vq; vq = vq->next) {
+ vq_aio_context[vq->value] = ctx;
+ }
+ } else {
+ /* Round-robin vq:IOThread assignment */
+ for (unsigned i = cur_iothread; i < num_queues;
+ i += num_iothreads) {
+ vq_aio_context[i] = ctx;
+ }
+ }
+
+ cur_iothread++;
+ }
+}
+
/* Context: QEMU global mutex held */
bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
VirtIOBlockDataPlane **dataplane,
@@ -58,7 +95,7 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
*dataplane = NULL;
- if (conf->iothread) {
+ if (conf->iothread || conf->iothread_vq_mapping_list) {
if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
error_setg(errp,
"device is incompatible with iothread "
@@ -86,13 +123,24 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
s = g_new0(VirtIOBlockDataPlane, 1);
s->vdev = vdev;
s->conf = conf;
+ s->vq_aio_context = g_new(AioContext *, conf->num_queues);
+
+ if (conf->iothread_vq_mapping_list) {
+ apply_vq_mapping(conf->iothread_vq_mapping_list, s->vq_aio_context,
+ conf->num_queues);
+ } else if (conf->iothread) {
+ AioContext *ctx = iothread_get_aio_context(conf->iothread);
+ for (unsigned i = 0; i < conf->num_queues; i++) {
+ s->vq_aio_context[i] = ctx;
+ }
- if (conf->iothread) {
- s->iothread = conf->iothread;
- object_ref(OBJECT(s->iothread));
- s->ctx = iothread_get_aio_context(s->iothread);
+ /* Released in virtio_blk_data_plane_destroy() */
+ object_ref(OBJECT(conf->iothread));
} else {
- s->ctx = qemu_get_aio_context();
+ AioContext *ctx = qemu_get_aio_context();
+ for (unsigned i = 0; i < conf->num_queues; i++) {
+ s->vq_aio_context[i] = ctx;
+ }
}
*dataplane = s;
@@ -104,6 +152,7 @@ bool virtio_blk_data_plane_create(VirtIODevice *vdev, VirtIOBlkConf *conf,
void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
{
VirtIOBlock *vblk;
+ VirtIOBlkConf *conf = s->conf;
if (!s) {
return;
@@ -111,9 +160,21 @@ void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
vblk = VIRTIO_BLK(s->vdev);
assert(!vblk->dataplane_started);
- if (s->iothread) {
- object_unref(OBJECT(s->iothread));
+
+ if (conf->iothread_vq_mapping_list) {
+ IOThreadVirtQueueMappingList *node;
+
+ for (node = conf->iothread_vq_mapping_list; node; node = node->next) {
+ IOThread *iothread = iothread_by_id(node->value->iothread);
+ object_unref(OBJECT(iothread));
+ }
+ }
+
+ if (conf->iothread) {
+ object_unref(OBJECT(conf->iothread));
}
+
+ g_free(s->vq_aio_context);
g_free(s);
}
@@ -177,19 +238,13 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
trace_virtio_blk_data_plane_start(s);
- r = blk_set_aio_context(s->conf->conf.blk, s->ctx, &local_err);
+ r = blk_set_aio_context(s->conf->conf.blk, s->vq_aio_context[0],
+ &local_err);
if (r < 0) {
error_report_err(local_err);
goto fail_aio_context;
}
- /* Kick right away to begin processing requests already in vring */
- for (i = 0; i < nvqs; i++) {
- VirtQueue *vq = virtio_get_queue(s->vdev, i);
-
- event_notifier_set(virtio_queue_get_host_notifier(vq));
- }
-
/*
* These fields must be visible to the IOThread when it processes the
* virtqueue, otherwise it will think dataplane has not started yet.
@@ -206,8 +261,12 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
if (!blk_in_drain(s->conf->conf.blk)) {
for (i = 0; i < nvqs; i++) {
VirtQueue *vq = virtio_get_queue(s->vdev, i);
+ AioContext *ctx = s->vq_aio_context[i];
- virtio_queue_aio_attach_host_notifier(vq, s->ctx);
+ /* Kick right away to begin processing requests already in vring */
+ event_notifier_set(virtio_queue_get_host_notifier(vq));
+
+ virtio_queue_aio_attach_host_notifier(vq, ctx);
}
}
return 0;
@@ -236,23 +295,18 @@ int virtio_blk_data_plane_start(VirtIODevice *vdev)
*
* Context: BH in IOThread
*/
-static void virtio_blk_data_plane_stop_bh(void *opaque)
+static void virtio_blk_data_plane_stop_vq_bh(void *opaque)
{
- VirtIOBlockDataPlane *s = opaque;
- unsigned i;
-
- for (i = 0; i < s->conf->num_queues; i++) {
- VirtQueue *vq = virtio_get_queue(s->vdev, i);
- EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq);
+ VirtQueue *vq = opaque;
+ EventNotifier *host_notifier = virtio_queue_get_host_notifier(vq);
- virtio_queue_aio_detach_host_notifier(vq, s->ctx);
+ virtio_queue_aio_detach_host_notifier(vq, qemu_get_current_aio_context());
- /*
- * Test and clear notifier after disabling event, in case poll callback
- * didn't have time to run.
- */
- virtio_queue_host_notifier_read(host_notifier);
- }
+ /*
+ * Test and clear notifier after disabling event, in case poll callback
+ * didn't have time to run.
+ */
+ virtio_queue_host_notifier_read(host_notifier);
}
/* Context: QEMU global mutex held */
@@ -279,7 +333,12 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
trace_virtio_blk_data_plane_stop(s);
if (!blk_in_drain(s->conf->conf.blk)) {
- aio_wait_bh_oneshot(s->ctx, virtio_blk_data_plane_stop_bh, s);
+ for (i = 0; i < nvqs; i++) {
+ VirtQueue *vq = virtio_get_queue(s->vdev, i);
+ AioContext *ctx = s->vq_aio_context[i];
+
+ aio_wait_bh_oneshot(ctx, virtio_blk_data_plane_stop_vq_bh, vq);
+ }
}
/*
@@ -322,3 +381,23 @@ void virtio_blk_data_plane_stop(VirtIODevice *vdev)
s->stopping = false;
}
+
+void virtio_blk_data_plane_detach(VirtIOBlockDataPlane *s)
+{
+ VirtIODevice *vdev = VIRTIO_DEVICE(s->vdev);
+
+ for (uint16_t i = 0; i < s->conf->num_queues; i++) {
+ VirtQueue *vq = virtio_get_queue(vdev, i);
+ virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
+ }
+}
+
+void virtio_blk_data_plane_attach(VirtIOBlockDataPlane *s)
+{
+ VirtIODevice *vdev = VIRTIO_DEVICE(s->vdev);
+
+ for (uint16_t i = 0; i < s->conf->num_queues; i++) {
+ VirtQueue *vq = virtio_get_queue(vdev, i);
+ virtio_queue_aio_attach_host_notifier(vq, s->vq_aio_context[i]);
+ }
+}
diff --git a/hw/block/dataplane/virtio-blk.h b/hw/block/dataplane/virtio-blk.h
index 5e18bb99ae..1a806fe447 100644
--- a/hw/block/dataplane/virtio-blk.h
+++ b/hw/block/dataplane/virtio-blk.h
@@ -28,4 +28,7 @@ void virtio_blk_data_plane_notify(VirtIOBlockDataPlane *s, VirtQueue *vq);
int virtio_blk_data_plane_start(VirtIODevice *vdev);
void virtio_blk_data_plane_stop(VirtIODevice *vdev);
+void virtio_blk_data_plane_detach(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_attach(VirtIOBlockDataPlane *s);
+
#endif /* HW_DATAPLANE_VIRTIO_BLK_H */
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index ec9ed09a6a..46e73b2c96 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -1151,6 +1151,7 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
return;
}
}
+
virtio_blk_handle_vq(s, vq);
}
@@ -1463,6 +1464,68 @@ static int virtio_blk_load_device(VirtIODevice *vdev, QEMUFile *f,
return 0;
}
+static bool
+validate_iothread_vq_mapping_list(IOThreadVirtQueueMappingList *list,
+ uint16_t num_queues, Error **errp)
+{
+ g_autofree unsigned long *vqs = bitmap_new(num_queues);
+ g_autoptr(GHashTable) iothreads =
+ g_hash_table_new(g_str_hash, g_str_equal);
+
+ for (IOThreadVirtQueueMappingList *node = list; node; node = node->next) {
+ const char *name = node->value->iothread;
+ uint16List *vq;
+
+ if (!iothread_by_id(name)) {
+ error_setg(errp, "IOThread \"%s\" object does not exist", name);
+ return false;
+ }
+
+ if (!g_hash_table_add(iothreads, (gpointer)name)) {
+ error_setg(errp,
+ "duplicate IOThread name \"%s\" in iothread-vq-mapping",
+ name);
+ return false;
+ }
+
+ if (node != list) {
+ if (!!node->value->vqs != !!list->value->vqs) {
+ error_setg(errp, "either all items in iothread-vq-mapping "
+ "must have vqs or none of them must have it");
+ return false;
+ }
+ }
+
+ for (vq = node->value->vqs; vq; vq = vq->next) {
+ if (vq->value >= num_queues) {
+ error_setg(errp, "vq index %u for IOThread \"%s\" must be "
+ "less than num_queues %u in iothread-vq-mapping",
+ vq->value, name, num_queues);
+ return false;
+ }
+
+ if (test_and_set_bit(vq->value, vqs)) {
+ error_setg(errp, "cannot assign vq %u to IOThread \"%s\" "
+ "because it is already assigned", vq->value, name);
+ return false;
+ }
+ }
+ }
+
+ if (list->value->vqs) {
+ for (uint16_t i = 0; i < num_queues; i++) {
+ if (!test_bit(i, vqs)) {
+ error_setg(errp,
+ "missing vq %u IOThread assignment in iothread-vq-mapping",
+ i);
+ return false;
+ }
+ }
+ }
+
+ return true;
+}
+
static void virtio_resize_cb(void *opaque)
{
VirtIODevice *vdev = opaque;
@@ -1487,34 +1550,24 @@ static void virtio_blk_resize(void *opaque)
static void virtio_blk_drained_begin(void *opaque)
{
VirtIOBlock *s = opaque;
- VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
- AioContext *ctx = blk_get_aio_context(s->conf.conf.blk);
if (!s->dataplane || !s->dataplane_started) {
return;
}
- for (uint16_t i = 0; i < s->conf.num_queues; i++) {
- VirtQueue *vq = virtio_get_queue(vdev, i);
- virtio_queue_aio_detach_host_notifier(vq, ctx);
- }
+ virtio_blk_data_plane_detach(s->dataplane);
}
/* Resume virtqueue ioeventfd processing after drain */
static void virtio_blk_drained_end(void *opaque)
{
VirtIOBlock *s = opaque;
- VirtIODevice *vdev = VIRTIO_DEVICE(opaque);
- AioContext *ctx = blk_get_aio_context(s->conf.conf.blk);
if (!s->dataplane || !s->dataplane_started) {
return;
}
- for (uint16_t i = 0; i < s->conf.num_queues; i++) {
- VirtQueue *vq = virtio_get_queue(vdev, i);
- virtio_queue_aio_attach_host_notifier(vq, ctx);
- }
+ virtio_blk_data_plane_attach(s->dataplane);
}
static const BlockDevOps virtio_block_ops = {
@@ -1600,6 +1653,19 @@ static void virtio_blk_device_realize(DeviceState *dev, Error **errp)
return;
}
+ if (conf->iothread_vq_mapping_list) {
+ if (conf->iothread) {
+ error_setg(errp, "iothread and iothread-vq-mapping properties "
+ "cannot be set at the same time");
+ return;
+ }
+
+ if (!validate_iothread_vq_mapping_list(conf->iothread_vq_mapping_list,
+ conf->num_queues, errp)) {
+ return;
+ }
+ }
+
s->config_size = virtio_get_config_size(&virtio_blk_cfg_size_params,
s->host_features);
virtio_init(vdev, VIRTIO_ID_BLOCK, s->config_size);
@@ -1702,6 +1768,8 @@ static Property virtio_blk_properties[] = {
DEFINE_PROP_BOOL("seg-max-adjust", VirtIOBlock, conf.seg_max_adjust, true),
DEFINE_PROP_LINK("iothread", VirtIOBlock, conf.iothread, TYPE_IOTHREAD,
IOThread *),
+ DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST("iothread-vq-mapping", VirtIOBlock,
+ conf.iothread_vq_mapping_list),
DEFINE_PROP_BIT64("discard", VirtIOBlock, host_features,
VIRTIO_BLK_F_DISCARD, true),
DEFINE_PROP_BOOL("report-discard-granularity", VirtIOBlock,
diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h
index 9881009c22..5e4091e4da 100644
--- a/include/hw/virtio/virtio-blk.h
+++ b/include/hw/virtio/virtio-blk.h
@@ -21,6 +21,7 @@
#include "sysemu/block-backend.h"
#include "sysemu/block-ram-registrar.h"
#include "qom/object.h"
+#include "qapi/qapi-types-virtio.h"
#define TYPE_VIRTIO_BLK "virtio-blk-device"
OBJECT_DECLARE_SIMPLE_TYPE(VirtIOBlock, VIRTIO_BLK)
@@ -37,6 +38,7 @@ struct VirtIOBlkConf
{
BlockConf conf;
IOThread *iothread;
+ IOThreadVirtQueueMappingList *iothread_vq_mapping_list;
char *serial;
uint32_t request_merging;
uint16_t num_queues;
--
2.39.3
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