This implements the core part of dataplane feature of virtio-scsi.
A few fields are added in VirtIOSCSICommon to maintain the dataplane
status. These fields are managed by a new source file:
virtio-scsi-dataplane.c.
Most code in this file will run on an iothread, unless otherwise
commented as in a global mutex context, such as those functions to
start, stop and setting the iothread property.
Upon start, we set up guest/host event notifiers, in a same way as
virtio-blk does. The handlers then pop request from vring and call into
virtio-scsi.c functions to process it. So we need to make sure make all
those called functions work with iothread, too.
Signed-off-by: Fam Zheng <f...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
hw/scsi/Makefile.objs | 2 +-
hw/scsi/virtio-scsi-dataplane.c | 222 ++++++++++++++++++++++++++++++++++++++++
include/hw/virtio/virtio-scsi.h | 25 ++++-
3 files changed, 245 insertions(+), 4 deletions(-)
create mode 100644 hw/scsi/virtio-scsi-dataplane.c
diff --git a/hw/scsi/Makefile.objs b/hw/scsi/Makefile.objs
index 121ddc5..40c79d3 100644
--- a/hw/scsi/Makefile.objs
+++ b/hw/scsi/Makefile.objs
@@ -8,6 +8,6 @@ common-obj-$(CONFIG_ESP_PCI) += esp-pci.o
obj-$(CONFIG_PSERIES) += spapr_vscsi.o
ifeq ($(CONFIG_VIRTIO),y)
-obj-y += virtio-scsi.o
+obj-y += virtio-scsi.o virtio-scsi-dataplane.o
obj-$(CONFIG_VHOST_SCSI) += vhost-scsi.o
endif
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
new file mode 100644
index 0000000..acbf622
--- /dev/null
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -0,0 +1,222 @@
+/*
+ * Virtio SCSI dataplane
+ *
+ * Copyright Red Hat, Inc. 2014
+ *
+ * Authors:
+ * Fam Zheng <f...@redhat.com>
+ *
+ * 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 "hw/virtio/virtio-scsi.h"
+#include "qemu/error-report.h"
+#include <hw/scsi/scsi.h>
+#include <block/scsi.h>
+#include <hw/virtio/virtio-bus.h>
+#include "hw/virtio/virtio-access.h"
+#include "stdio.h"
+
+/* Context: QEMU global mutex held */
+void virtio_scsi_set_iothread(VirtIOSCSI *s, IOThread *iothread)
+{
+ BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+
+ assert(!s->ctx);
+ s->ctx = iothread_get_aio_context(vs->conf.iothread);
+
+ /* Don't try if transport does not support notifiers. */
+ if (!k->set_guest_notifiers || !k->set_host_notifier) {
+ fprintf(stderr, "virtio-scsi: Failed to set iothread "
+ "(transport does not support notifiers)");
+ exit(1);
+ }
+}
+
+static VirtIOSCSIVring *virtio_scsi_vring_init(VirtIOSCSI *s,
+ VirtQueue *vq,
+ EventNotifierHandler *handler,
+ int n)
+{
+ BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+ VirtIOSCSIVring *r = g_slice_new(VirtIOSCSIVring);
+
+ /* Set up virtqueue notify */
+ if (k->set_host_notifier(qbus->parent, n, true) != 0) {
+ fprintf(stderr, "virtio-scsi: Failed to set host notifier\n");
+ exit(1);
+ }
+ r->host_notifier = *virtio_queue_get_host_notifier(vq);
+ r->guest_notifier = *virtio_queue_get_guest_notifier(vq);
+ aio_set_event_notifier(s->ctx, &r->host_notifier, handler);
+
+ r->parent = s;
+
+ if (!vring_setup(&r->vring, VIRTIO_DEVICE(s), n)) {
+ fprintf(stderr, "virtio-scsi: VRing setup failed\n");
+ exit(1);
+ }
+ return r;
+}
+
+VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
+ VirtIOSCSIVring *vring)
+{
+ VirtIOSCSIReq *req = virtio_scsi_init_req(s, NULL);
+ int r;
+
+ req->vring = vring;
+ r = vring_pop((VirtIODevice *)s, &vring->vring, &req->elem);
+ if (r < 0) {
+ virtio_scsi_free_req(req);
+ req = NULL;
+ }
+ return req;
+}
+
+void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req)
+{
+ vring_push(&req->vring->vring, &req->elem,
+ req->qsgl.size + req->resp_iov.size);
+ event_notifier_set(&req->vring->guest_notifier);
+}
+
+static void virtio_scsi_iothread_handle_ctrl(EventNotifier *notifier)
+{
+ VirtIOSCSIVring *vring = container_of(notifier,
+ VirtIOSCSIVring, host_notifier);
+ VirtIOSCSI *s = VIRTIO_SCSI(vring->parent);
+ VirtIOSCSIReq *req;
+
+ event_notifier_test_and_clear(notifier);
+ while ((req = virtio_scsi_pop_req_vring(s, vring))) {
+ virtio_scsi_handle_ctrl_req(s, req);
+ }
+}
+
+static void virtio_scsi_iothread_handle_event(EventNotifier *notifier)
+{
+ VirtIOSCSIVring *vring = container_of(notifier,
+ VirtIOSCSIVring, host_notifier);
+ VirtIOSCSI *s = vring->parent;
+ VirtIODevice *vdev = VIRTIO_DEVICE(s);
+
+ event_notifier_test_and_clear(notifier);
+
+ if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+ return;
+ }
+
+ if (s->events_dropped) {
+ virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
+ }
+}
+
+static void virtio_scsi_iothread_handle_cmd(EventNotifier *notifier)
+{
+ VirtIOSCSIVring *vring = container_of(notifier,
+ VirtIOSCSIVring, host_notifier);
+ VirtIOSCSI *s = (VirtIOSCSI *)vring->parent;
+ VirtIOSCSIReq *req;
+
+ event_notifier_test_and_clear(notifier);
+ while ((req = virtio_scsi_pop_req_vring(s, vring))) {
+ virtio_scsi_handle_cmd_req(s, req);
+ }
+}
+
+/* Context: QEMU global mutex held */
+void virtio_scsi_dataplane_start(VirtIOSCSI *s)
+{
+ int i;
+ int rc;
+ BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+
+ if (s->dataplane_started ||
+ s->dataplane_starting ||
+ s->ctx != iothread_get_aio_context(vs->conf.iothread)) {
+ return;
+ }
+
+ s->dataplane_starting = true;
+
+ /* Set up guest notifier (irq) */
+ rc = k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, true);
+ if (rc != 0) {
+ fprintf(stderr, "virtio-scsi: Failed to set guest notifiers, "
+ "ensure -enable-kvm is set\n");
+ exit(1);
+ }
+
+ aio_context_acquire(s->ctx);
+ s->ctrl_vring = virtio_scsi_vring_init(s, vs->ctrl_vq,
+ virtio_scsi_iothread_handle_ctrl,
+ 0);
+ s->event_vring = virtio_scsi_vring_init(s, vs->event_vq,
+ virtio_scsi_iothread_handle_event,
+ 1);
+ s->cmd_vrings = g_malloc0(sizeof(VirtIOSCSIVring) * vs->conf.num_queues);
+ for (i = 0; i < vs->conf.num_queues; i++) {
+ s->cmd_vrings[i] =
+ virtio_scsi_vring_init(s, vs->cmd_vqs[i],
+ virtio_scsi_iothread_handle_cmd,
+ i + 2);
+ }
+
+ aio_context_release(s->ctx);
+ s->dataplane_starting = false;
+ s->dataplane_started = true;
+}
+
+/* Context: QEMU global mutex held */
+void virtio_scsi_dataplane_stop(VirtIOSCSI *s)
+{
+ BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(s)));
+ VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+ VirtIODevice *vdev = VIRTIO_DEVICE(s);
+ VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+ int i;
+
+ if (!s->dataplane_started || s->dataplane_stopping) {
+ return;
+ }
+ s->dataplane_stopping = true;
+ assert(s->ctx == iothread_get_aio_context(vs->conf.iothread));
+
+ aio_context_acquire(s->ctx);
+
+ aio_set_event_notifier(s->ctx, &s->ctrl_vring->host_notifier, NULL);
+ aio_set_event_notifier(s->ctx, &s->event_vring->host_notifier, NULL);
+ for (i = 0; i < vs->conf.num_queues; i++) {
+ aio_set_event_notifier(s->ctx, &s->cmd_vrings[i]->host_notifier, NULL);
+ }
+
+ bdrv_drain_all(); /* ensure there are no in-flight requests */
+
+ aio_context_release(s->ctx);
+
+ /* Sync vring state back to virtqueue so that non-dataplane request
+ * processing can continue when we disable the host notifier below.
+ */
+ vring_teardown(&s->ctrl_vring->vring, vdev, 0);
+ vring_teardown(&s->event_vring->vring, vdev, 1);
+ for (i = 0; i < vs->conf.num_queues; i++) {
+ vring_teardown(&s->cmd_vrings[i]->vring, vdev, 2 + i);
+ }
+
+ for (i = 0; i < vs->conf.num_queues + 2; i++) {
+ k->set_host_notifier(qbus->parent, i, false);
+ }
+
+ /* Clean up guest notifier (irq) */
+ k->set_guest_notifiers(qbus->parent, vs->conf.num_queues + 2, false);
+ s->dataplane_stopping = false;
+ s->dataplane_started = false;
+}
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index 1ed93ab..8e1968f 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -156,10 +156,10 @@ struct VirtIOSCSIConf {
IOThread *iothread;
};
-struct VirtIOSCSICommon;
+struct VirtIOSCSI;
typedef struct {
- struct VirtIOSCSICommon *parent;
+ struct VirtIOSCSI *parent;
Vring vring;
EventNotifier host_notifier;
EventNotifier guest_notifier;
@@ -176,12 +176,24 @@ typedef struct VirtIOSCSICommon {
VirtQueue **cmd_vqs;
} VirtIOSCSICommon;
-typedef struct {
+typedef struct VirtIOSCSI {
VirtIOSCSICommon parent_obj;
SCSIBus bus;
int resetting;
bool events_dropped;
+
+ /* Fields for dataplane below */
+ AioContext *ctx; /* one iothread per virtio-scsi-pci for now */
+
+ /* Vring is used instead of vq in dataplane code, because of the underlying
+ * memory layer thread safety */
+ VirtIOSCSIVring *ctrl_vring;
+ VirtIOSCSIVring *event_vring;
+ VirtIOSCSIVring **cmd_vrings;
+ bool dataplane_started;
+ bool dataplane_starting;
+ bool dataplane_stopping;
} VirtIOSCSI;
typedef struct VirtIOSCSIReq {
@@ -248,4 +260,11 @@ void virtio_scsi_free_req(VirtIOSCSIReq *req);
void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
uint32_t event, uint32_t reason);
+void virtio_scsi_set_iothread(VirtIOSCSI *s, IOThread *iothread);
+void virtio_scsi_dataplane_start(VirtIOSCSI *s);
+void virtio_scsi_dataplane_stop(VirtIOSCSI *s);
+void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req);
+VirtIOSCSIReq *virtio_scsi_pop_req_vring(VirtIOSCSI *s,
+ VirtIOSCSIVring *vring);
+
#endif /* _QEMU_VIRTIO_SCSI_H */
--
1.9.3
