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vhost: backend masking support
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Support backend guest notifier masking in vhost-net:
create eventfd at device init, when masked,
make vhost use that as eventfd instead of
sending an interrupt.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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@mstsirkin
mstsirkin committed Jan 7, 2013
1 parent 24f4fe3 commit f56a124
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Showing 5 changed files with 137 additions and 16 deletions.
95 changes: 82 additions & 13 deletions hw/vhost.c
View file
Expand Up @@ -612,7 +612,7 @@ static void vhost_log_stop(MemoryListener *listener,
/* FIXME: implement */
}

static int vhost_virtqueue_init(struct vhost_dev *dev,
static int vhost_virtqueue_start(struct vhost_dev *dev,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
unsigned idx)
Expand Down Expand Up @@ -681,16 +681,11 @@ static int vhost_virtqueue_init(struct vhost_dev *dev,
goto fail_kick;
}

file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
r = ioctl(dev->control, VHOST_SET_VRING_CALL, &file);
if (r) {
r = -errno;
goto fail_call;
}
/* Clear and discard previous events if any. */
event_notifier_test_and_clear(&vq->masked_notifier);

return 0;

fail_call:
fail_kick:
fail_alloc:
cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
Expand All @@ -708,7 +703,7 @@ static int vhost_virtqueue_init(struct vhost_dev *dev,
return r;
}

static void vhost_virtqueue_cleanup(struct vhost_dev *dev,
static void vhost_virtqueue_stop(struct vhost_dev *dev,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
unsigned idx)
Expand Down Expand Up @@ -746,11 +741,39 @@ static void vhost_eventfd_del(MemoryListener *listener,
{
}

static int vhost_virtqueue_init(struct vhost_dev *dev,
struct vhost_virtqueue *vq, int n)
{
struct vhost_vring_file file = {
.index = n,
};
int r = event_notifier_init(&vq->masked_notifier, 0);
if (r < 0) {
return r;
}

file.fd = event_notifier_get_fd(&vq->masked_notifier);
r = ioctl(dev->control, VHOST_SET_VRING_CALL, &file);
if (r) {
r = -errno;
goto fail_call;
}
return 0;
fail_call:
event_notifier_cleanup(&vq->masked_notifier);
return r;
}

static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
{
event_notifier_cleanup(&vq->masked_notifier);
}

int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,
bool force)
{
uint64_t features;
int r;
int i, r;
if (devfd >= 0) {
hdev->control = devfd;
} else {
Expand All @@ -768,6 +791,13 @@ int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,
if (r < 0) {
goto fail;
}

for (i = 0; i < hdev->nvqs; ++i) {
r = vhost_virtqueue_init(hdev, hdev->vqs + i, i);
if (r < 0) {
goto fail_vq;
}
}
hdev->features = features;

hdev->memory_listener = (MemoryListener) {
Expand Down Expand Up @@ -795,6 +825,10 @@ int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,
memory_listener_register(&hdev->memory_listener, &address_space_memory);
hdev->force = force;
return 0;
fail_vq:
while (--i >= 0) {
vhost_virtqueue_cleanup(hdev->vqs + i);
}
fail:
r = -errno;
close(hdev->control);
Expand All @@ -803,6 +837,10 @@ int vhost_dev_init(struct vhost_dev *hdev, int devfd, const char *devpath,

void vhost_dev_cleanup(struct vhost_dev *hdev)
{
int i;
for (i = 0; i < hdev->nvqs; ++i) {
vhost_virtqueue_cleanup(hdev->vqs + i);
}
memory_listener_unregister(&hdev->memory_listener);
g_free(hdev->mem);
g_free(hdev->mem_sections);
Expand Down Expand Up @@ -869,6 +907,37 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
}
}

/* Test and clear event pending status.
* Should be called after unmask to avoid losing events.
*/
bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n)
{
struct vhost_virtqueue *vq = hdev->vqs + n;
assert(hdev->started);
return event_notifier_test_and_clear(&vq->masked_notifier);
}

/* Mask/unmask events from this vq. */
void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
bool mask)
{
struct VirtQueue *vvq = virtio_get_queue(vdev, n);
int r;

assert(hdev->started);

struct vhost_vring_file file = {
.index = n,
};
if (mask) {
file.fd = event_notifier_get_fd(&hdev->vqs[n].masked_notifier);
} else {
file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
}
r = ioctl(hdev->control, VHOST_SET_VRING_CALL, &file);
assert(r >= 0);
}

/* Host notifiers must be enabled at this point. */
int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
{
Expand Down Expand Up @@ -900,7 +969,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
goto fail_mem;
}
for (i = 0; i < hdev->nvqs; ++i) {
r = vhost_virtqueue_init(hdev,
r = vhost_virtqueue_start(hdev,
vdev,
hdev->vqs + i,
i);
Expand All @@ -925,7 +994,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
fail_log:
fail_vq:
while (--i >= 0) {
vhost_virtqueue_cleanup(hdev,
vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
i);
Expand All @@ -946,7 +1015,7 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
int i, r;

for (i = 0; i < hdev->nvqs; ++i) {
vhost_virtqueue_cleanup(hdev,
vhost_virtqueue_stop(hdev,
vdev,
hdev->vqs + i,
i);
Expand Down
10 changes: 10 additions & 0 deletions hw/vhost.h
View file
Expand Up @@ -18,6 +18,7 @@ struct vhost_virtqueue {
void *ring;
unsigned long long ring_phys;
unsigned ring_size;
EventNotifier masked_notifier;
};

typedef unsigned long vhost_log_chunk_t;
Expand Down Expand Up @@ -53,4 +54,13 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);
void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev);

/* Test and clear masked event pending status.
* Should be called after unmask to avoid losing events.
*/
bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n);

/* Mask/unmask events from this vq.
*/
void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
bool mask);
#endif
27 changes: 24 additions & 3 deletions hw/vhost_net.c
View file
Expand Up @@ -109,6 +109,9 @@ struct vhost_net *vhost_net_init(NetClientState *backend, int devfd,
(1 << VHOST_NET_F_VIRTIO_NET_HDR);
net->backend = r;

net->dev.nvqs = 2;
net->dev.vqs = net->vqs;

r = vhost_dev_init(&net->dev, devfd, "/dev/vhost-net", force);
if (r < 0) {
goto fail;
Expand Down Expand Up @@ -143,9 +146,6 @@ int vhost_net_start(struct vhost_net *net,
struct vhost_vring_file file = { };
int r;

net->dev.nvqs = 2;
net->dev.vqs = net->vqs;

r = vhost_dev_enable_notifiers(&net->dev, dev);
if (r < 0) {
goto fail_notifiers;
Expand Down Expand Up @@ -200,6 +200,17 @@ void vhost_net_cleanup(struct vhost_net *net)
vhost_dev_cleanup(&net->dev);
g_free(net);
}

bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
{
return vhost_virtqueue_pending(&net->dev, idx);
}

void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
int idx, bool mask)
{
vhost_virtqueue_mask(&net->dev, dev, idx, mask);
}
#else
struct vhost_net *vhost_net_init(NetClientState *backend, int devfd,
bool force)
Expand Down Expand Up @@ -234,4 +245,14 @@ unsigned vhost_net_get_features(struct vhost_net *net, unsigned features)
void vhost_net_ack_features(struct vhost_net *net, unsigned features)
{
}

bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
{
return -ENOSYS;
}

void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
int idx, bool mask)
{
}
#endif
3 changes: 3 additions & 0 deletions hw/vhost_net.h
View file
Expand Up @@ -17,4 +17,7 @@ void vhost_net_cleanup(VHostNetState *net);
unsigned vhost_net_get_features(VHostNetState *net, unsigned features);
void vhost_net_ack_features(VHostNetState *net, unsigned features);

bool vhost_net_virtqueue_pending(VHostNetState *net, int n);
void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
int idx, bool mask);
#endif
18 changes: 18 additions & 0 deletions hw/virtio-net.c
View file
Expand Up @@ -1010,6 +1010,22 @@ static NetClientInfo net_virtio_info = {
.link_status_changed = virtio_net_set_link_status,
};

static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
{
VirtIONet *n = to_virtio_net(vdev);
assert(n->vhost_started);
return vhost_net_virtqueue_pending(tap_get_vhost_net(n->nic->nc.peer), idx);
}

static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
bool mask)
{
VirtIONet *n = to_virtio_net(vdev);
assert(n->vhost_started);
vhost_net_virtqueue_mask(tap_get_vhost_net(n->nic->nc.peer),
vdev, idx, mask);
}

VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
virtio_net_conf *net)
{
Expand All @@ -1026,6 +1042,8 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
n->vdev.bad_features = virtio_net_bad_features;
n->vdev.reset = virtio_net_reset;
n->vdev.set_status = virtio_net_set_status;
n->vdev.guest_notifier_mask = virtio_net_guest_notifier_mask;
n->vdev.guest_notifier_pending = virtio_net_guest_notifier_pending;
n->rx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_rx);

if (net->tx && strcmp(net->tx, "timer") && strcmp(net->tx, "bh")) {
Expand Down

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