vhost: replace single worker pointer with xarray

The next patch allows userspace to create multiple workers per device,
so this patch replaces the vhost_worker pointer with an xarray so we
can store mupltiple workers and look them up.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Message-Id: <20230626232307.97930-15-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 12203d3..ffbaf7d 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -280,7 +280,11 @@ EXPORT_SYMBOL_GPL(vhost_vq_flush);
 
 void vhost_dev_flush(struct vhost_dev *dev)
 {
-       vhost_worker_flush(dev->worker);
+       struct vhost_worker *worker;
+       unsigned long i;
+
+       xa_for_each(&dev->worker_xa, i, worker)
+               vhost_worker_flush(worker);
 }
 EXPORT_SYMBOL_GPL(vhost_dev_flush);
 
@@ -482,7 +486,6 @@ void vhost_dev_init(struct vhost_dev *dev,
        dev->umem = NULL;
        dev->iotlb = NULL;
        dev->mm = NULL;
-       dev->worker = NULL;
        dev->iov_limit = iov_limit;
        dev->weight = weight;
        dev->byte_weight = byte_weight;
@@ -492,7 +495,7 @@ void vhost_dev_init(struct vhost_dev *dev,
        INIT_LIST_HEAD(&dev->read_list);
        INIT_LIST_HEAD(&dev->pending_list);
        spin_lock_init(&dev->iotlb_lock);
-
+       xa_init_flags(&dev->worker_xa, XA_FLAGS_ALLOC);
 
        for (i = 0; i < dev->nvqs; ++i) {
                vq = dev->vqs[i];
@@ -554,15 +557,35 @@ static void vhost_detach_mm(struct vhost_dev *dev)
        dev->mm = NULL;
 }
 
-static void vhost_worker_free(struct vhost_dev *dev)
+static void vhost_worker_destroy(struct vhost_dev *dev,
+                                struct vhost_worker *worker)
+{
+       if (!worker)
+               return;
+
+       WARN_ON(!llist_empty(&worker->work_list));
+       xa_erase(&dev->worker_xa, worker->id);
+       vhost_task_stop(worker->vtsk);
+       kfree(worker);
+}
+
+static void vhost_workers_free(struct vhost_dev *dev)
 {
-       if (!dev->worker)
+       struct vhost_worker *worker;
+       unsigned long i;
+
+       if (!dev->use_worker)
                return;
 
-       WARN_ON(!llist_empty(&dev->worker->work_list));
-       vhost_task_stop(dev->worker->vtsk);
-       kfree(dev->worker);
-       dev->worker = NULL;
+       for (i = 0; i < dev->nvqs; i++)
+               dev->vqs[i]->worker = NULL;
+       /*
+        * Free the default worker we created and cleanup workers userspace
+        * created but couldn't clean up (it forgot or crashed).
+        */
+       xa_for_each(&dev->worker_xa, i, worker)
+               vhost_worker_destroy(dev, worker);
+       xa_destroy(&dev->worker_xa);
 }
 
 static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
@@ -570,6 +593,8 @@ static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
        struct vhost_worker *worker;
        struct vhost_task *vtsk;
        char name[TASK_COMM_LEN];
+       int ret;
+       u32 id;
 
        worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
        if (!worker)
@@ -584,16 +609,18 @@ static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev)
        init_llist_head(&worker->work_list);
        worker->kcov_handle = kcov_common_handle();
        worker->vtsk = vtsk;
-       /*
-        * vsock can already try to queue so make sure llist and vtsk are both
-        * set before vhost_work_queue sees dev->worker is set.
-        */
-       smp_wmb();
-       dev->worker = worker;
 
        vhost_task_start(vtsk);
+
+       ret = xa_alloc(&dev->worker_xa, &id, worker, xa_limit_32b, GFP_KERNEL);
+       if (ret < 0)
+               goto stop_worker;
+       worker->id = id;
+
        return worker;
 
+stop_worker:
+       vhost_task_stop(vtsk);
 free_worker:
        kfree(worker);
        return NULL;
@@ -650,6 +677,11 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
                        err = -ENOMEM;
                        goto err_worker;
                }
+               /*
+                * vsock can already try to queue so make sure the worker
+                * is setup before vhost_vq_work_queue sees vq->worker is set.
+                */
+               smp_wmb();
 
                for (i = 0; i < dev->nvqs; i++)
                        dev->vqs[i]->worker = worker;
@@ -751,7 +783,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
        dev->iotlb = NULL;
        vhost_clear_msg(dev);
        wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
-       vhost_worker_free(dev);
+       vhost_workers_free(dev);
        vhost_detach_mm(dev);
 }
 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index b850f53..31937e9 100644 (file)
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -30,6 +30,7 @@ struct vhost_worker {
        struct vhost_task       *vtsk;
        struct llist_head       work_list;
        u64                     kcov_handle;
+       u32                     id;
 };
 
 /* Poll a file (eventfd or socket) */
@@ -159,7 +160,6 @@ struct vhost_dev {
        struct vhost_virtqueue **vqs;
        int nvqs;
        struct eventfd_ctx *log_ctx;
-       struct vhost_worker *worker;
        struct vhost_iotlb *umem;
        struct vhost_iotlb *iotlb;
        spinlock_t iotlb_lock;
@@ -169,6 +169,7 @@ struct vhost_dev {
        int iov_limit;
        int weight;
        int byte_weight;
+       struct xarray worker_xa;
        bool use_worker;
        int (*msg_handler)(struct vhost_dev *dev, u32 asid,
                           struct vhost_iotlb_msg *msg);