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virtio-scsi: add iothread-vq-mapping parameter
Allow virtio-scsi virtqueues to be assigned to different IOThreads. This makes it possible to take advantage of host multi-queue block layer scalability by assigning virtqueues that have affinity with vCPUs to different IOThreads that have affinity with host CPUs. The same feature was introduced for virtio-blk in the past: https://developers.redhat.com/articles/2024/09/05/scaling-virtio-blk-disk-io-iothread-virtqueue-mapping Here are fio randread 4k iodepth=64 results from a 4 vCPU guest with an Intel P4800X SSD: iothreads IOPS ------------------------------ 1 189576 2 312698 4 346744 Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-ID: <20250311132616.1049687-12-stefanha@redhat.com> Tested-by: Peter Krempa <pkrempa@redhat.com> [kwolf: Updated 051 output, virtio-scsi can now use any iothread] Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi
Kevin Wolf
parent
b50629c335
commit
2e8e18c2e4
4 changed files with 108 additions and 52 deletions
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@ -18,6 +18,7 @@
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#include "system/block-backend.h"
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#include "hw/scsi/scsi.h"
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#include "scsi/constants.h"
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#include "hw/virtio/iothread-vq-mapping.h"
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#include "hw/virtio/virtio-bus.h"
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/* Context: BQL held */
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@ -27,8 +28,16 @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
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VirtIODevice *vdev = VIRTIO_DEVICE(s);
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BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
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VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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uint16_t num_vqs = vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED;
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if (vs->conf.iothread) {
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if (vs->conf.iothread && vs->conf.iothread_vq_mapping_list) {
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error_setg(errp,
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"iothread and iothread-vq-mapping properties cannot be set "
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"at the same time");
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return;
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}
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if (vs->conf.iothread || vs->conf.iothread_vq_mapping_list) {
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if (!k->set_guest_notifiers || !k->ioeventfd_assign) {
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error_setg(errp,
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"device is incompatible with iothread "
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@ -39,15 +48,50 @@ void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp)
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error_setg(errp, "ioeventfd is required for iothread");
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return;
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}
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s->ctx = iothread_get_aio_context(vs->conf.iothread);
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} else {
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if (!virtio_device_ioeventfd_enabled(vdev)) {
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}
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s->vq_aio_context = g_new(AioContext *, num_vqs);
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if (vs->conf.iothread_vq_mapping_list) {
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if (!iothread_vq_mapping_apply(vs->conf.iothread_vq_mapping_list,
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s->vq_aio_context, num_vqs, errp)) {
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g_free(s->vq_aio_context);
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s->vq_aio_context = NULL;
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return;
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}
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s->ctx = qemu_get_aio_context();
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} else if (vs->conf.iothread) {
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AioContext *ctx = iothread_get_aio_context(vs->conf.iothread);
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for (uint16_t i = 0; i < num_vqs; i++) {
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s->vq_aio_context[i] = ctx;
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}
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/* Released in virtio_scsi_dataplane_cleanup() */
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object_ref(OBJECT(vs->conf.iothread));
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} else {
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AioContext *ctx = qemu_get_aio_context();
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for (unsigned i = 0; i < num_vqs; i++) {
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s->vq_aio_context[i] = ctx;
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}
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}
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}
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/* Context: BQL held */
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void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s)
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{
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VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
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if (vs->conf.iothread_vq_mapping_list) {
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iothread_vq_mapping_cleanup(vs->conf.iothread_vq_mapping_list);
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}
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if (vs->conf.iothread) {
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object_unref(OBJECT(vs->conf.iothread));
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}
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g_free(s->vq_aio_context);
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s->vq_aio_context = NULL;
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}
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static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
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{
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BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
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@ -66,31 +110,20 @@ static int virtio_scsi_set_host_notifier(VirtIOSCSI *s, VirtQueue *vq, int n)
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}
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/* Context: BH in IOThread */
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static void virtio_scsi_dataplane_stop_bh(void *opaque)
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static void virtio_scsi_dataplane_stop_vq_bh(void *opaque)
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{
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VirtIOSCSI *s = opaque;
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VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
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AioContext *ctx = qemu_get_current_aio_context();
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VirtQueue *vq = opaque;
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EventNotifier *host_notifier;
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int i;
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virtio_queue_aio_detach_host_notifier(vs->ctrl_vq, s->ctx);
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host_notifier = virtio_queue_get_host_notifier(vs->ctrl_vq);
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virtio_queue_aio_detach_host_notifier(vq, ctx);
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host_notifier = virtio_queue_get_host_notifier(vq);
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/*
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* Test and clear notifier after disabling event, in case poll callback
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* didn't have time to run.
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*/
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virtio_queue_host_notifier_read(host_notifier);
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virtio_queue_aio_detach_host_notifier(vs->event_vq, s->ctx);
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host_notifier = virtio_queue_get_host_notifier(vs->event_vq);
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virtio_queue_host_notifier_read(host_notifier);
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for (i = 0; i < vs->conf.num_queues; i++) {
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virtio_queue_aio_detach_host_notifier(vs->cmd_vqs[i], s->ctx);
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host_notifier = virtio_queue_get_host_notifier(vs->cmd_vqs[i]);
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virtio_queue_host_notifier_read(host_notifier);
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}
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}
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/* Context: BQL held */
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@ -154,11 +187,14 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
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smp_wmb(); /* paired with aio_notify_accept() */
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if (s->bus.drain_count == 0) {
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virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx);
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virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx);
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virtio_queue_aio_attach_host_notifier(vs->ctrl_vq,
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s->vq_aio_context[0]);
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virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq,
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s->vq_aio_context[1]);
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for (i = 0; i < vs->conf.num_queues; i++) {
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virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx);
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AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
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virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], ctx);
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}
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}
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return 0;
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@ -207,7 +243,11 @@ void virtio_scsi_dataplane_stop(VirtIODevice *vdev)
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s->dataplane_stopping = true;
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if (s->bus.drain_count == 0) {
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aio_wait_bh_oneshot(s->ctx, virtio_scsi_dataplane_stop_bh, s);
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for (i = 0; i < vs->conf.num_queues + VIRTIO_SCSI_VQ_NUM_FIXED; i++) {
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VirtQueue *vq = virtio_get_queue(&vs->parent_obj, i);
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AioContext *ctx = s->vq_aio_context[i];
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aio_wait_bh_oneshot(ctx, virtio_scsi_dataplane_stop_vq_bh, vq);
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}
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}
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blk_drain_all(); /* ensure there are no in-flight requests */
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@ -27,6 +27,7 @@
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#include "hw/qdev-properties.h"
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#include "hw/scsi/scsi.h"
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#include "scsi/constants.h"
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#include "hw/virtio/iothread-vq-mapping.h"
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#include "hw/virtio/virtio-bus.h"
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#include "hw/virtio/virtio-access.h"
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#include "trace.h"
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@ -318,13 +319,6 @@ static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
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g_free(n);
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}
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static inline void virtio_scsi_ctx_check(VirtIOSCSI *s, SCSIDevice *d)
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{
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if (s->dataplane_started && d && blk_is_available(d->conf.blk)) {
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assert(blk_get_aio_context(d->conf.blk) == s->ctx);
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}
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}
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static void virtio_scsi_do_one_tmf_bh(VirtIOSCSIReq *req)
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{
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VirtIOSCSI *s = req->dev;
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@ -517,9 +511,11 @@ static void virtio_scsi_flush_defer_tmf_to_aio_context(VirtIOSCSI *s)
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assert(!s->dataplane_started);
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if (s->ctx) {
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for (uint32_t i = 0; i < s->parent_obj.conf.num_queues; i++) {
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AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
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/* Our BH only runs after previously scheduled BHs */
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aio_wait_bh_oneshot(s->ctx, dummy_bh, NULL);
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aio_wait_bh_oneshot(ctx, dummy_bh, NULL);
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}
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}
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@ -575,7 +571,6 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
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AioContext *ctx;
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int ret = 0;
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virtio_scsi_ctx_check(s, d);
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/* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE". */
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req->resp.tmf.response = VIRTIO_SCSI_S_OK;
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@ -639,6 +634,8 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
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case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
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case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET: {
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g_autoptr(GHashTable) aio_contexts = g_hash_table_new(NULL, NULL);
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if (!d) {
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goto fail;
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}
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@ -648,8 +645,15 @@ static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
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qatomic_inc(&req->remaining);
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ctx = s->ctx ?: qemu_get_aio_context();
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virtio_scsi_defer_tmf_to_aio_context(req, ctx);
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for (uint32_t i = 0; i < s->parent_obj.conf.num_queues; i++) {
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ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED + i];
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if (!g_hash_table_add(aio_contexts, ctx)) {
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continue; /* skip previously added AioContext */
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}
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virtio_scsi_defer_tmf_to_aio_context(req, ctx);
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}
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virtio_scsi_tmf_dec_remaining(req);
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ret = -EINPROGRESS;
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@ -770,9 +774,12 @@ static void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq)
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*/
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static bool virtio_scsi_defer_to_dataplane(VirtIOSCSI *s)
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{
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if (!s->ctx || s->dataplane_started) {
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if (s->dataplane_started) {
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return false;
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}
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if (s->vq_aio_context[0] == qemu_get_aio_context()) {
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return false; /* not using IOThreads */
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}
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virtio_device_start_ioeventfd(&s->parent_obj.parent_obj);
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return !s->dataplane_fenced;
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@ -946,7 +953,6 @@ static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
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virtio_scsi_complete_cmd_req(req);
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return -ENOENT;
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}
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virtio_scsi_ctx_check(s, d);
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req->sreq = scsi_req_new(d, req->req.cmd.tag,
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virtio_scsi_get_lun(req->req.cmd.lun),
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req->req.cmd.cdb, vs->cdb_size, req);
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@ -1218,14 +1224,16 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
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{
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VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
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VirtIOSCSI *s = VIRTIO_SCSI(vdev);
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AioContext *ctx = s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED];
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SCSIDevice *sd = SCSI_DEVICE(dev);
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int ret;
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if (s->ctx && !s->dataplane_fenced) {
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ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
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if (ret < 0) {
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return;
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}
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if (ctx != qemu_get_aio_context() && !s->dataplane_fenced) {
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/*
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* Try to make the BlockBackend's AioContext match ours. Ignore failure
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* because I/O will still work although block jobs and other users
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* might be slower when multiple AioContexts use a BlockBackend.
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*/
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blk_set_aio_context(sd->conf.blk, ctx, NULL);
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}
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if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
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@ -1260,7 +1268,7 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
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qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
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if (s->ctx) {
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if (s->vq_aio_context[VIRTIO_SCSI_VQ_NUM_FIXED] != qemu_get_aio_context()) {
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/* If other users keep the BlockBackend in the iothread, that's ok */
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blk_set_aio_context(sd->conf.blk, qemu_get_aio_context(), NULL);
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}
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@ -1294,7 +1302,7 @@ static void virtio_scsi_drained_begin(SCSIBus *bus)
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for (uint32_t i = 0; i < total_queues; i++) {
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VirtQueue *vq = virtio_get_queue(vdev, i);
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virtio_queue_aio_detach_host_notifier(vq, s->ctx);
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virtio_queue_aio_detach_host_notifier(vq, s->vq_aio_context[i]);
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}
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}
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@ -1320,10 +1328,12 @@ static void virtio_scsi_drained_end(SCSIBus *bus)
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for (uint32_t i = 0; i < total_queues; i++) {
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VirtQueue *vq = virtio_get_queue(vdev, i);
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AioContext *ctx = s->vq_aio_context[i];
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if (vq == vs->event_vq) {
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virtio_queue_aio_attach_host_notifier_no_poll(vq, s->ctx);
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virtio_queue_aio_attach_host_notifier_no_poll(vq, ctx);
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} else {
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virtio_queue_aio_attach_host_notifier(vq, s->ctx);
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virtio_queue_aio_attach_host_notifier(vq, ctx);
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}
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}
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}
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@ -1430,12 +1440,13 @@ void virtio_scsi_common_unrealize(DeviceState *dev)
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virtio_cleanup(vdev);
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}
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/* main loop */
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static void virtio_scsi_device_unrealize(DeviceState *dev)
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{
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VirtIOSCSI *s = VIRTIO_SCSI(dev);
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virtio_scsi_reset_tmf_bh(s);
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virtio_scsi_dataplane_cleanup(s);
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qbus_set_hotplug_handler(BUS(&s->bus), NULL);
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virtio_scsi_common_unrealize(dev);
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qemu_mutex_destroy(&s->tmf_bh_lock);
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@ -1460,6 +1471,8 @@ static const Property virtio_scsi_properties[] = {
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VIRTIO_SCSI_F_CHANGE, true),
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DEFINE_PROP_LINK("iothread", VirtIOSCSI, parent_obj.conf.iothread,
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TYPE_IOTHREAD, IOThread *),
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DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST("iothread-vq-mapping", VirtIOSCSI,
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parent_obj.conf.iothread_vq_mapping_list),
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};
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static const VMStateDescription vmstate_virtio_scsi = {
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@ -22,6 +22,7 @@
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#include "hw/virtio/virtio.h"
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#include "hw/scsi/scsi.h"
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#include "chardev/char-fe.h"
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#include "qapi/qapi-types-virtio.h"
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#include "system/iothread.h"
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#define TYPE_VIRTIO_SCSI_COMMON "virtio-scsi-common"
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@ -60,6 +61,7 @@ struct VirtIOSCSIConf {
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CharBackend chardev;
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uint32_t boot_tpgt;
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IOThread *iothread;
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IOThreadVirtQueueMappingList *iothread_vq_mapping_list;
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};
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struct VirtIOSCSI;
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@ -97,7 +99,7 @@ struct VirtIOSCSI {
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QTAILQ_HEAD(, VirtIOSCSIReq) tmf_bh_list;
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/* Fields for dataplane below */
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AioContext *ctx; /* one iothread per virtio-scsi-pci for now */
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AioContext **vq_aio_context; /* per-virtqueue AioContext pointer */
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bool dataplane_started;
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bool dataplane_starting;
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@ -115,6 +117,7 @@ void virtio_scsi_common_realize(DeviceState *dev,
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void virtio_scsi_common_unrealize(DeviceState *dev);
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void virtio_scsi_dataplane_setup(VirtIOSCSI *s, Error **errp);
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void virtio_scsi_dataplane_cleanup(VirtIOSCSI *s);
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int virtio_scsi_dataplane_start(VirtIODevice *s);
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void virtio_scsi_dataplane_stop(VirtIODevice *s);
|
||||
|
||||
|
|
|
|||
|
|
@ -181,7 +181,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
|
|||
|
||||
Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-scsi,id=virtio-scsi1 -device scsi-hd,bus=virtio-scsi1.0,drive=disk,share-rw=on
|
||||
QEMU X.Y.Z monitor - type 'help' for more information
|
||||
(qemu) QEMU_PROG: -device scsi-hd,bus=virtio-scsi1.0,drive=disk,share-rw=on: Cannot change iothread of active block backend
|
||||
(qemu) quit
|
||||
|
||||
Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on
|
||||
QEMU X.Y.Z monitor - type 'help' for more information
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue