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[RFC v2 6/7] vhost: Route guest->host notification through shadow virtqu
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From: |
Eugenio Pérez |
|
Subject: |
[RFC v2 6/7] vhost: Route guest->host notification through shadow virtqueue |
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Date: |
Tue, 9 Feb 2021 16:37:56 +0100 |
Shadow virtqueue notifications forwarding is disabled when vhost_dev
stops.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
hw/virtio/vhost-shadow-virtqueue.h | 7 ++
include/hw/virtio/vhost.h | 4 +
hw/virtio/vhost-shadow-virtqueue.c | 97 ++++++++++++++++++-
hw/virtio/vhost.c | 148 ++++++++++++++++++++++++++++-
4 files changed, 253 insertions(+), 3 deletions(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.h
b/hw/virtio/vhost-shadow-virtqueue.h
index 6cc18d6acb..c45035c4b7 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -17,6 +17,13 @@
typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
+bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev,
+ unsigned idx,
+ VhostShadowVirtqueue *svq);
+void vhost_shadow_vq_stop_rcu(struct vhost_dev *dev,
+ unsigned idx,
+ VhostShadowVirtqueue *svq);
+
VhostShadowVirtqueue *vhost_shadow_vq_new(struct vhost_dev *dev, int idx);
void vhost_shadow_vq_free(VhostShadowVirtqueue *vq);
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index ac963bf23d..884818b109 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -55,6 +55,8 @@ struct vhost_iommu {
QLIST_ENTRY(vhost_iommu) iommu_next;
};
+typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
+
typedef struct VhostDevConfigOps {
/* Vhost device config space changed callback
*/
@@ -83,7 +85,9 @@ struct vhost_dev {
uint64_t backend_cap;
bool started;
bool log_enabled;
+ bool sw_lm_enabled;
uint64_t log_size;
+ VhostShadowVirtqueue **shadow_vqs;
Error *migration_blocker;
const VhostOps *vhost_ops;
void *opaque;
diff --git a/hw/virtio/vhost-shadow-virtqueue.c
b/hw/virtio/vhost-shadow-virtqueue.c
index b5d2645ae0..01f282d434 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -8,9 +8,12 @@
*/
#include "hw/virtio/vhost-shadow-virtqueue.h"
+#include "hw/virtio/vhost.h"
+
+#include "standard-headers/linux/vhost_types.h"
#include "qemu/error-report.h"
-#include "qemu/event_notifier.h"
+#include "qemu/main-loop.h"
/* Shadow virtqueue to relay notifications */
typedef struct VhostShadowVirtqueue {
@@ -18,8 +21,95 @@ typedef struct VhostShadowVirtqueue {
EventNotifier kick_notifier;
/* Shadow call notifier, sent to vhost */
EventNotifier call_notifier;
+
+ /* Borrowed virtqueue's guest to host notifier. */
+ EventNotifier host_notifier;
+
+ /* Virtio queue shadowing */
+ VirtQueue *vq;
} VhostShadowVirtqueue;
+/* Forward guest notifications */
+static void vhost_handle_guest_kick(EventNotifier *n)
+{
+ VhostShadowVirtqueue *svq = container_of(n, VhostShadowVirtqueue,
+ host_notifier);
+
+ if (event_notifier_test_and_clear(n)) {
+ event_notifier_set(&svq->kick_notifier);
+ }
+}
+
+/*
+ * Start shadow virtqueue operation.
+ * @dev vhost device
+ * @hidx vhost virtqueue index
+ * @svq Shadow Virtqueue
+ *
+ * Run in RCU context
+ */
+bool vhost_shadow_vq_start_rcu(struct vhost_dev *dev,
+ unsigned idx,
+ VhostShadowVirtqueue *svq)
+{
+ EventNotifier *vq_host_notifier = virtio_queue_get_host_notifier(svq->vq);
+ struct vhost_vring_file kick_file = {
+ .index = idx,
+ .fd = event_notifier_get_fd(&svq->kick_notifier),
+ };
+ int r;
+
+ /* Check that notifications are still going directly to vhost dev */
+ assert(virtio_queue_host_notifier_status(svq->vq));
+
+ event_notifier_init_fd(&svq->host_notifier,
+ event_notifier_get_fd(vq_host_notifier));
+ event_notifier_set_handler(&svq->host_notifier, vhost_handle_guest_kick);
+
+ r = dev->vhost_ops->vhost_set_vring_kick(dev, &kick_file);
+ if (unlikely(r != 0)) {
+ error_report("Couldn't set kick fd: %s", strerror(errno));
+ goto err_set_vring_kick;
+ }
+
+ /* Check for pending notifications from the guest */
+ vhost_handle_guest_kick(&svq->host_notifier);
+
+ return true;
+
+err_set_vring_kick:
+ event_notifier_set_handler(&svq->host_notifier, NULL);
+
+ return false;
+}
+
+/*
+ * Stop shadow virtqueue operation.
+ * @dev vhost device
+ * @idx vhost queue index
+ * @svq Shadow Virtqueue
+ *
+ * Run in RCU context
+ */
+void vhost_shadow_vq_stop_rcu(struct vhost_dev *dev,
+ unsigned idx,
+ VhostShadowVirtqueue *svq)
+{
+ EventNotifier *vq_host_notifier = virtio_queue_get_host_notifier(svq->vq);
+ struct vhost_vring_file kick_file = {
+ .index = idx,
+ .fd = event_notifier_get_fd(vq_host_notifier),
+ };
+ int r;
+
+ /* Restore vhost kick */
+ r = dev->vhost_ops->vhost_set_vring_kick(dev, &kick_file);
+ /* Cannot do a lot of things */
+ assert(r == 0);
+
+ event_notifier_set_handler(&svq->host_notifier, NULL);
+}
+
/*
* Creates vhost shadow virtqueue, and instruct vhost device to use the shadow
* methods and file descriptors.
@@ -27,8 +117,11 @@ typedef struct VhostShadowVirtqueue {
VhostShadowVirtqueue *vhost_shadow_vq_new(struct vhost_dev *dev, int idx)
{
g_autofree VhostShadowVirtqueue *svq = g_new0(VhostShadowVirtqueue, 1);
+ int vq_idx = dev->vq_index + idx;
int r;
+ svq->vq = virtio_get_queue(dev->vdev, vq_idx);
+
r = event_notifier_init(&svq->kick_notifier, 0);
if (r != 0) {
error_report("Couldn't create kick event notifier: %s",
@@ -43,7 +136,7 @@ VhostShadowVirtqueue *vhost_shadow_vq_new(struct vhost_dev
*dev, int idx)
goto err_init_call_notifier;
}
- return svq;
+ return g_steal_pointer(&svq);
err_init_call_notifier:
event_notifier_cleanup(&svq->kick_notifier);
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 8fbf14385e..9d4728e545 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -25,6 +25,7 @@
#include "exec/address-spaces.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-access.h"
+#include "hw/virtio/vhost-shadow-virtqueue.h"
#include "migration/blocker.h"
#include "migration/qemu-file-types.h"
#include "sysemu/dma.h"
@@ -937,6 +938,84 @@ static void vhost_log_global_stop(MemoryListener *listener)
}
}
+static int vhost_sw_live_migration_stop(struct vhost_dev *dev)
+{
+ int idx;
+
+ WITH_RCU_READ_LOCK_GUARD() {
+ dev->sw_lm_enabled = false;
+
+ for (idx = 0; idx < dev->nvqs; ++idx) {
+ vhost_shadow_vq_stop_rcu(dev, idx, dev->shadow_vqs[idx]);
+ }
+ }
+
+ for (idx = 0; idx < dev->nvqs; ++idx) {
+ vhost_shadow_vq_free(dev->shadow_vqs[idx]);
+ }
+
+ g_free(dev->shadow_vqs);
+ dev->shadow_vqs = NULL;
+ return 0;
+}
+
+static int vhost_sw_live_migration_start(struct vhost_dev *dev)
+{
+ int idx;
+
+ dev->shadow_vqs = g_new0(VhostShadowVirtqueue *, dev->nvqs);
+ for (idx = 0; idx < dev->nvqs; ++idx) {
+ dev->shadow_vqs[idx] = vhost_shadow_vq_new(dev, idx);
+ if (unlikely(dev->shadow_vqs[idx] == NULL)) {
+ goto err;
+ }
+ }
+
+ WITH_RCU_READ_LOCK_GUARD() {
+ for (idx = 0; idx < dev->nvqs; ++idx) {
+ bool ok = vhost_shadow_vq_start_rcu(dev, idx,
+ dev->shadow_vqs[idx]);
+
+ if (!ok) {
+ int stop_idx = idx;
+
+ while (--stop_idx >= 0) {
+ vhost_shadow_vq_stop_rcu(dev, idx,
+ dev->shadow_vqs[stop_idx]);
+ }
+
+ goto err;
+ }
+ }
+ }
+
+ dev->sw_lm_enabled = true;
+ return 0;
+
+err:
+ for (; idx >= 0; --idx) {
+ vhost_shadow_vq_free(dev->shadow_vqs[idx]);
+ }
+ g_free(dev->shadow_vqs[idx]);
+
+ return -1;
+}
+
+static int vhost_sw_live_migration_enable(struct vhost_dev *dev,
+ bool enable_lm)
+{
+ int r;
+
+ if (enable_lm == dev->sw_lm_enabled) {
+ return 0;
+ }
+
+ r = enable_lm ? vhost_sw_live_migration_start(dev)
+ : vhost_sw_live_migration_stop(dev);
+
+ return r;
+}
+
static void vhost_log_start(MemoryListener *listener,
MemoryRegionSection *section,
int old, int new)
@@ -1381,6 +1460,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
hdev->log = NULL;
hdev->log_size = 0;
hdev->log_enabled = false;
+ hdev->sw_lm_enabled = false;
hdev->started = false;
memory_listener_register(&hdev->memory_listener, &address_space_memory);
QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
@@ -1486,6 +1566,10 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev,
VirtIODevice *vdev)
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
int i, r;
+ if (hdev->sw_lm_enabled) {
+ vhost_sw_live_migration_enable(hdev, false);
+ }
+
for (i = 0; i < hdev->nvqs; ++i) {
r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
false);
@@ -1808,6 +1892,11 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice
*vdev)
hdev->vhost_ops->vhost_dev_start(hdev, false);
}
for (i = 0; i < hdev->nvqs; ++i) {
+ if (hdev->sw_lm_enabled) {
+ vhost_shadow_vq_stop_rcu(hdev, i, hdev->shadow_vqs[i]);
+ vhost_shadow_vq_free(hdev->shadow_vqs[i]);
+ }
+
vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
@@ -1821,6 +1910,8 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice
*vdev)
memory_listener_unregister(&hdev->iommu_listener);
}
vhost_log_put(hdev, true);
+ g_free(hdev->shadow_vqs);
+ hdev->sw_lm_enabled = false;
hdev->started = false;
hdev->vdev = NULL;
}
@@ -1837,5 +1928,60 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
void qmp_x_vhost_enable_shadow_vq(const char *name, bool enable, Error **errp)
{
- error_setg(errp, "Shadow virtqueue still not implemented");
+ struct vhost_dev *hdev, *hdev_err;
+ VirtIODevice *vdev;
+ const char *err_cause = NULL;
+ int r;
+ ErrorClass err_class = ERROR_CLASS_GENERIC_ERROR;
+
+ QLIST_FOREACH(hdev, &vhost_devices, entry) {
+ if (hdev->vdev && 0 == strcmp(hdev->vdev->name, name)) {
+ vdev = hdev->vdev;
+ break;
+ }
+ }
+
+ if (!hdev) {
+ err_class = ERROR_CLASS_DEVICE_NOT_FOUND;
+ err_cause = "Device not found";
+ goto not_found_err;
+ }
+
+ for ( ; hdev; hdev = QLIST_NEXT(hdev, entry)) {
+ if (vdev != hdev->vdev) {
+ continue;
+ }
+
+ if (!hdev->started) {
+ err_cause = "Device is not started";
+ goto err;
+ }
+
+ r = vhost_sw_live_migration_enable(hdev, enable);
+ if (unlikely(r)) {
+ err_cause = "Error enabling (see monitor)";
+ goto err;
+ }
+ }
+
+ return;
+
+err:
+ QLIST_FOREACH(hdev_err, &vhost_devices, entry) {
+ if (hdev_err == hdev) {
+ break;
+ }
+
+ if (vdev != hdev->vdev) {
+ continue;
+ }
+
+ vhost_sw_live_migration_enable(hdev, !enable);
+ }
+
+not_found_err:
+ if (err_cause) {
+ error_set(errp, err_class,
+ "Can't enable shadow vq on %s: %s", name, err_cause);
+ }
}
--
2.27.0