um: virtio: Implement VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS

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>

diff --git a/arch/um/drivers/vhost_user.h b/arch/um/drivers/vhost_user.h
index 45ff5ea22fea5d5d84053b1ab517472628b0d158..6c71b600517746c7309197ea87eb3089666d3210 100644 (file)
--- a/arch/um/drivers/vhost_user.h
+++ b/arch/um/drivers/vhost_user.h
@@ -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)
@@ -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,
@@ -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 {

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index 023ced2250ea7ef57c274440c752aefb9b6bd67d..9b4c5b7c0f0d7e60270ec63460eb9cd137163d84 100644 (file)
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -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;
@@ -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;
 
@@ -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,
@@ -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;
@@ -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:
@@ -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);
@@ -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);
@@ -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)
@@ -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)
@@ -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:
@@ -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)
@@ -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;