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um: virtio: Implement VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS
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Implement in-band notifications that are necessary for running
vhost-user devices under externally synchronized time-travel
mode (which is in a follow-up patch). This feature makes what
usually should be eventfd notifications in-band messages.

We'll prefer this feature, under the assumption that only a
few (simulation) devices will ever support it, since it's not
very efficient.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
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Johannes Berg authored and Richard Weinberger committed Mar 29, 2020
1 parent 4b786e2 commit dd9ada5
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Showing 2 changed files with 75 additions and 22 deletions.
12 changes: 8 additions & 4 deletions arch/um/drivers/vhost_user.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,9 +10,10 @@
/* Feature bits */
#define VHOST_USER_F_PROTOCOL_FEATURES 30
/* Protocol feature bits */
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
#define VHOST_USER_PROTOCOL_F_CONFIG 9
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
#define VHOST_USER_PROTOCOL_F_CONFIG 9
#define VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS 14
/* Vring state index masks */
#define VHOST_USER_VRING_INDEX_MASK 0xff
#define VHOST_USER_VRING_POLL_MASK BIT(8)
Expand All @@ -24,7 +25,8 @@
/* Supported protocol features */
#define VHOST_USER_SUPPORTED_PROTOCOL_F (BIT_ULL(VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
BIT_ULL(VHOST_USER_PROTOCOL_F_SLAVE_REQ) | \
BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG))
BIT_ULL(VHOST_USER_PROTOCOL_F_CONFIG) | \
BIT_ULL(VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS))

enum vhost_user_request {
VHOST_USER_GET_FEATURES = 1,
Expand Down Expand Up @@ -52,12 +54,14 @@ enum vhost_user_request {
VHOST_USER_SET_VRING_ENDIAN = 23,
VHOST_USER_GET_CONFIG = 24,
VHOST_USER_SET_CONFIG = 25,
VHOST_USER_VRING_KICK = 35,
};

enum vhost_user_slave_request {
VHOST_USER_SLAVE_IOTLB_MSG = 1,
VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
VHOST_USER_SLAVE_VRING_CALL = 4,
};

struct vhost_user_header {
Expand Down
85 changes: 67 additions & 18 deletions arch/um/drivers/virtio_uml.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ struct virtio_uml_device {
struct virtio_device vdev;
struct platform_device *pdev;

spinlock_t sock_lock;
int sock, req_fd;
u64 features;
u64 protocol_features;
Expand Down Expand Up @@ -189,6 +190,7 @@ static int vhost_user_send(struct virtio_uml_device *vu_dev,
int *fds, size_t num_fds)
{
size_t size = sizeof(msg->header) + msg->header.size;
unsigned long flags;
bool request_ack;
int rc;

Expand All @@ -207,24 +209,28 @@ static int vhost_user_send(struct virtio_uml_device *vu_dev,
if (request_ack)
msg->header.flags |= VHOST_USER_FLAG_NEED_REPLY;

spin_lock_irqsave(&vu_dev->sock_lock, flags);
rc = full_sendmsg_fds(vu_dev->sock, msg, size, fds, num_fds);
if (rc < 0)
return rc;
goto out;

if (request_ack) {
uint64_t status;

rc = vhost_user_recv_u64(vu_dev, &status);
if (rc)
return rc;
goto out;

if (status) {
vu_err(vu_dev, "slave reports error: %llu\n", status);
return -EIO;
rc = -EIO;
goto out;
}
}

return 0;
out:
spin_unlock_irqrestore(&vu_dev->sock_lock, flags);
return rc;
}

static int vhost_user_send_no_payload(struct virtio_uml_device *vu_dev,
Expand Down Expand Up @@ -324,6 +330,7 @@ static void vhost_user_reply(struct virtio_uml_device *vu_dev,
static irqreturn_t vu_req_interrupt(int irq, void *data)
{
struct virtio_uml_device *vu_dev = data;
struct virtqueue *vq;
int response = 1;
struct {
struct vhost_user_msg msg;
Expand All @@ -343,6 +350,15 @@ static irqreturn_t vu_req_interrupt(int irq, void *data)
virtio_config_changed(&vu_dev->vdev);
response = 0;
break;
case VHOST_USER_SLAVE_VRING_CALL:
virtio_device_for_each_vq((&vu_dev->vdev), vq) {
if (vq->index == msg.msg.payload.vring_state.index) {
response = 0;
vring_interrupt(0 /* ignored */, vq);
break;
}
}
break;
case VHOST_USER_SLAVE_IOTLB_MSG:
/* not supported - VIRTIO_F_IOMMU_PLATFORM */
case VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG:
Expand Down Expand Up @@ -684,6 +700,15 @@ static bool vu_notify(struct virtqueue *vq)
const uint64_t n = 1;
int rc;

if (info->kick_fd < 0) {
struct virtio_uml_device *vu_dev;

vu_dev = to_virtio_uml_device(vq->vdev);

return vhost_user_set_vring_state(vu_dev, VHOST_USER_VRING_KICK,
vq->index, 0) == 0;
}

do {
rc = os_write_file(info->kick_fd, &n, sizeof(n));
} while (rc == -EINTR);
Expand Down Expand Up @@ -749,10 +774,13 @@ static void vu_del_vq(struct virtqueue *vq)
{
struct virtio_uml_vq_info *info = vq->priv;

um_free_irq(VIRTIO_IRQ, vq);
if (info->call_fd >= 0) {
um_free_irq(VIRTIO_IRQ, vq);
os_close_file(info->call_fd);
}

os_close_file(info->call_fd);
os_close_file(info->kick_fd);
if (info->kick_fd >= 0)
os_close_file(info->kick_fd);

vring_del_virtqueue(vq);
kfree(info);
Expand Down Expand Up @@ -782,6 +810,15 @@ static int vu_setup_vq_call_fd(struct virtio_uml_device *vu_dev,
int call_fds[2];
int rc;

/* no call FD needed/desired in this case */
if (vu_dev->protocol_features &
BIT_ULL(VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS) &&
vu_dev->protocol_features &
BIT_ULL(VHOST_USER_PROTOCOL_F_SLAVE_REQ)) {
info->call_fd = -1;
return 0;
}

/* Use a pipe for call fd, since SIGIO is not supported for eventfd */
rc = os_pipe(call_fds, true, true);
if (rc < 0)
Expand Down Expand Up @@ -838,10 +875,15 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
vq->priv = info;
num = virtqueue_get_vring_size(vq);

rc = os_eventfd(0, 0);
if (rc < 0)
goto error_kick;
info->kick_fd = rc;
if (vu_dev->protocol_features &
BIT_ULL(VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS)) {
info->kick_fd = -1;
} else {
rc = os_eventfd(0, 0);
if (rc < 0)
goto error_kick;
info->kick_fd = rc;
}

rc = vu_setup_vq_call_fd(vu_dev, vq);
if (rc)
Expand All @@ -866,10 +908,13 @@ static struct virtqueue *vu_setup_vq(struct virtio_device *vdev,
return vq;

error_setup:
um_free_irq(VIRTIO_IRQ, vq);
os_close_file(info->call_fd);
if (info->call_fd >= 0) {
um_free_irq(VIRTIO_IRQ, vq);
os_close_file(info->call_fd);
}
error_call:
os_close_file(info->kick_fd);
if (info->kick_fd >= 0)
os_close_file(info->kick_fd);
error_kick:
vring_del_virtqueue(vq);
error_create:
Expand Down Expand Up @@ -908,10 +953,12 @@ static int vu_find_vqs(struct virtio_device *vdev, unsigned nvqs,
list_for_each_entry(vq, &vdev->vqs, list) {
struct virtio_uml_vq_info *info = vq->priv;

rc = vhost_user_set_vring_kick(vu_dev, vq->index,
info->kick_fd);
if (rc)
goto error_setup;
if (info->kick_fd >= 0) {
rc = vhost_user_set_vring_kick(vu_dev, vq->index,
info->kick_fd);
if (rc)
goto error_setup;
}

rc = vhost_user_set_vring_enable(vu_dev, vq->index, true);
if (rc)
Expand Down Expand Up @@ -1008,6 +1055,8 @@ static int virtio_uml_probe(struct platform_device *pdev)
return rc;
vu_dev->sock = rc;

spin_lock_init(&vu_dev->sock_lock);

rc = vhost_user_init(vu_dev);
if (rc)
goto error_init;
Expand Down

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