virtio: find_vqs/del_vqs virtio operations

This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations,
and updates all drivers. This is needed for MSI support, because MSI
needs to know the total number of vectors upfront.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)

10 files changed, 183 insertions, 89 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index db55a50d9f6a..07d8e595e51f 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -288,7 +288,7 @@ static int virtblk_probe(struct virtio_device *vdev)
         sg_init_table(vblk->sg, vblk->sg_elems);
 
         /* We expect one virtqueue, for output. */
-        vblk->vq = vdev->config->find_vq(vdev, 0, blk_done, "requests");
+        vblk->vq = virtio_find_single_vq(vdev, blk_done, "requests");
         if (IS_ERR(vblk->vq)) {
                 err = PTR_ERR(vblk->vq);
                 goto out_free_vblk;
@@ -388,7 +388,7 @@ out_put_disk:
 out_mempool:
         mempool_destroy(vblk->pool);
 out_free_vq:
-        vdev->config->del_vq(vblk->vq);
+        vdev->config->del_vqs(vdev);
 out_free_vblk:
         kfree(vblk);
 out:
@@ -409,7 +409,7 @@ static void virtblk_remove(struct virtio_device *vdev)
         blk_cleanup_queue(vblk->disk->queue);
         put_disk(vblk->disk);
         mempool_destroy(vblk->pool);
-        vdev->config->del_vq(vblk->vq);
+        vdev->config->del_vqs(vdev);
         kfree(vblk);
 }
 
diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index 2aeafcea95fe..f2041fede822 100644
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -94,13 +94,13 @@ static int virtrng_probe(struct virtio_device *vdev)
         int err;
 
         /* We expect a single virtqueue. */
-        vq = vdev->config->find_vq(vdev, 0, random_recv_done, "input");
+        vq = virtio_find_single_vq(vdev, random_recv_done, "input");
         if (IS_ERR(vq))
                 return PTR_ERR(vq);
 
         err = hwrng_register(&virtio_hwrng);
         if (err) {
-                vdev->config->del_vq(vq);
+                vdev->config->del_vqs(vdev);
                 return err;
         }
 
@@ -112,7 +112,7 @@ static void virtrng_remove(struct virtio_device *vdev)
 {
         vdev->config->reset(vdev);
         hwrng_unregister(&virtio_hwrng);
-        vdev->config->del_vq(vq);
+        vdev->config->del_vqs(vdev);
 }
 
 static struct virtio_device_id id_table[] = {
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 58684e4a0814..c74dacfa6795 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -188,6 +188,9 @@ static void hvc_handle_input(struct virtqueue *vq)
  * Finally we put our input buffer in the input queue, ready to receive. */
 static int __devinit virtcons_probe(struct virtio_device *dev)
 {
+        vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
+        const char *names[] = { "input", "output" };
+        struct virtqueue *vqs[2];
         int err;
 
         vdev = dev;
@@ -199,20 +202,15 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
                 goto fail;
         }
 
-        /* Find the input queue. */
+        /* Find the queues. */
         /* FIXME: This is why we want to wean off hvc: we do nothing
          * when input comes in. */
-        in_vq = vdev->config->find_vq(vdev, 0, hvc_handle_input, "input");
-        if (IS_ERR(in_vq)) {
-                err = PTR_ERR(in_vq);
+        err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+        if (err)
                 goto free;
-        }
 
-        out_vq = vdev->config->find_vq(vdev, 1, NULL, "output");
-        if (IS_ERR(out_vq)) {
-                err = PTR_ERR(out_vq);
-                goto free_in_vq;
-        }
+        in_vq = vqs[0];
+        out_vq = vqs[1];
 
         /* Start using the new console output. */
         virtio_cons.get_chars = get_chars;
@@ -233,17 +231,15 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
         hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
         if (IS_ERR(hvc)) {
                 err = PTR_ERR(hvc);
-                goto free_out_vq;
+                goto free_vqs;
         }
 
         /* Register the input buffer the first time. */
         add_inbuf();
         return 0;
 
-free_out_vq:
-        vdev->config->del_vq(out_vq);
-free_in_vq:
-        vdev->config->del_vq(in_vq);
+free_vqs:
+        vdev->config->del_vqs(vdev);
 free:
         kfree(inbuf);
 fail:
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 4babed899d59..e082cdac88b4 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -313,6 +313,38 @@ static void lg_del_vq(struct virtqueue *vq)
         kfree(lvq);
 }
 
+static void lg_del_vqs(struct virtio_device *vdev)
+{
+        struct virtqueue *vq, *n;
+
+        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+                lg_del_vq(vq);
+}
+
+static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+                       struct virtqueue *vqs[],
+                       vq_callback_t *callbacks[],
+                       const char *names[])
+{
+        struct lguest_device *ldev = to_lgdev(vdev);
+        int i;
+
+        /* We must have this many virtqueues. */
+        if (nvqs > ldev->desc->num_vq)
+                return -ENOENT;
+
+        for (i = 0; i < nvqs; ++i) {
+                vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
+                if (IS_ERR(vqs[i]))
+                        goto error;
+        }
+        return 0;
+
+error:
+        lg_del_vqs(vdev);
+        return PTR_ERR(vqs[i]);
+}
+
 /* The ops structure which hooks everything together. */
 static struct virtio_config_ops lguest_config_ops = {
         .get_features = lg_get_features,
@@ -322,8 +354,8 @@ static struct virtio_config_ops lguest_config_ops = {
         .get_status = lg_get_status,
         .set_status = lg_set_status,
         .reset = lg_reset,
-        .find_vq = lg_find_vq,
-        .del_vq = lg_del_vq,
+        .find_vqs = lg_find_vqs,
+        .del_vqs = lg_del_vqs,
 };
 
 /* The root device for the lguest virtio devices.  This makes them appear as
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index be3b734ff5a1..7fa620ddeb21 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -845,6 +845,10 @@ static int virtnet_probe(struct virtio_device *vdev)
         int err;
         struct net_device *dev;
         struct virtnet_info *vi;
+        struct virtqueue *vqs[3];
+        vq_callback_t *callbacks[] = { skb_recv_done, skb_xmit_done, NULL};
+        const char *names[] = { "input", "output", "control" };
+        int nvqs;
 
         /* Allocate ourselves a network device with room for our info */
         dev = alloc_etherdev(sizeof(struct virtnet_info));
@@ -905,25 +909,19 @@ static int virtnet_probe(struct virtio_device *vdev)
         if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
                 vi->mergeable_rx_bufs = true;
 
-        /* We expect two virtqueues, receive then send. */
-        vi->rvq = vdev->config->find_vq(vdev, 0, skb_recv_done, "input");
-        if (IS_ERR(vi->rvq)) {
-                err = PTR_ERR(vi->rvq);
+        /* We expect two virtqueues, receive then send,
+         * and optionally control. */
+        nvqs = virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ) ? 3 : 2;
+
+        err = vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names);
+        if (err)
                 goto free;
-        }
 
-        vi->svq = vdev->config->find_vq(vdev, 1, skb_xmit_done, "output");
-        if (IS_ERR(vi->svq)) {
-                err = PTR_ERR(vi->svq);
-                goto free_recv;
-        }
+        vi->rvq = vqs[0];
+        vi->svq = vqs[1];
 
         if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ)) {
-                vi->cvq = vdev->config->find_vq(vdev, 2, NULL, "control");
-                if (IS_ERR(vi->cvq)) {
-                        err = PTR_ERR(vi->svq);
-                        goto free_send;
-                }
+                vi->cvq = vqs[2];
 
                 if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VLAN))
                         dev->features |= NETIF_F_HW_VLAN_FILTER;
@@ -941,7 +939,7 @@ static int virtnet_probe(struct virtio_device *vdev)
         err = register_netdev(dev);
         if (err) {
                 pr_debug("virtio_net: registering device failed\n");
-                goto free_ctrl;
+                goto free_vqs;
         }
 
         /* Last of all, set up some receive buffers. */
@@ -962,13 +960,8 @@ static int virtnet_probe(struct virtio_device *vdev)
 
 unregister:
         unregister_netdev(dev);
-free_ctrl:
-        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
-                vdev->config->del_vq(vi->cvq);
-free_send:
-        vdev->config->del_vq(vi->svq);
-free_recv:
-        vdev->config->del_vq(vi->rvq);
+free_vqs:
+        vdev->config->del_vqs(vdev);
 free:
         free_netdev(dev);
         return err;
@@ -994,12 +987,10 @@ static void virtnet_remove(struct virtio_device *vdev)
 
         BUG_ON(vi->num != 0);
 
-        vdev->config->del_vq(vi->svq);
-        vdev->config->del_vq(vi->rvq);
-        if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_VQ))
-                vdev->config->del_vq(vi->cvq);
         unregister_netdev(vi->dev);
 
+        vdev->config->del_vqs(vi->vdev);
+
         while (vi->pages)
                 __free_pages(get_a_page(vi, GFP_KERNEL), 0);
 
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index ba8995fbf041..e38e5d306faf 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -227,6 +227,38 @@ static void kvm_del_vq(struct virtqueue *vq)
                                        KVM_S390_VIRTIO_RING_ALIGN));
 }
 
+static void kvm_del_vqs(struct virtio_device *vdev)
+{
+        struct virtqueue *vq, *n;
+
+        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+                kvm_del_vq(vq);
+}
+
+static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+                        struct virtqueue *vqs[],
+                        vq_callback_t *callbacks[],
+                        const char *names[])
+{
+        struct kvm_device *kdev = to_kvmdev(vdev);
+        int i;
+
+        /* We must have this many virtqueues. */
+        if (nvqs > kdev->desc->num_vq)
+                return -ENOENT;
+
+        for (i = 0; i < nvqs; ++i) {
+                vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
+                if (IS_ERR(vqs[i]))
+                        goto error;
+        }
+        return 0;
+
+error:
+        kvm_del_vqs(vdev);
+        return PTR_ERR(vqs[i]);
+}
+
 /*
  * The config ops structure as defined by virtio config
  */
@@ -238,8 +270,8 @@ static struct virtio_config_ops kvm_vq_configspace_ops = {
         .get_status = kvm_get_status,
         .set_status = kvm_set_status,
         .reset = kvm_reset,
-        .find_vq = kvm_find_vq,
-        .del_vq = kvm_del_vq,
+        .find_vqs = kvm_find_vqs,
+        .del_vqs = kvm_del_vqs,
 };
 
 /*
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 0fa73b4d18b0..26b278264796 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -204,6 +204,9 @@ static int balloon(void *_vballoon)
 static int virtballoon_probe(struct virtio_device *vdev)
 {
         struct virtio_balloon *vb;
+        struct virtqueue *vqs[2];
+        vq_callback_t *callbacks[] = { balloon_ack, balloon_ack };
+        const char *names[] = { "inflate", "deflate" };
         int err;
 
         vdev->priv = vb = kmalloc(sizeof(*vb), GFP_KERNEL);
@@ -218,22 +221,17 @@ static int virtballoon_probe(struct virtio_device *vdev)
         vb->vdev = vdev;
 
         /* We expect two virtqueues. */
-        vb->inflate_vq = vdev->config->find_vq(vdev, 0, balloon_ack, "inflate");
-        if (IS_ERR(vb->inflate_vq)) {
-                err = PTR_ERR(vb->inflate_vq);
+        err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
+        if (err)
                 goto out_free_vb;
-        }
 
-        vb->deflate_vq = vdev->config->find_vq(vdev, 1, balloon_ack, "deflate");
-        if (IS_ERR(vb->deflate_vq)) {
-                err = PTR_ERR(vb->deflate_vq);
-                goto out_del_inflate_vq;
-        }
+        vb->inflate_vq = vqs[0];
+        vb->deflate_vq = vqs[1];
 
         vb->thread = kthread_run(balloon, vb, "vballoon");
         if (IS_ERR(vb->thread)) {
                 err = PTR_ERR(vb->thread);
-                goto out_del_deflate_vq;
+                goto out_del_vqs;
         }
 
         vb->tell_host_first
@@ -241,10 +239,8 @@ static int virtballoon_probe(struct virtio_device *vdev)
 
         return 0;
 
-out_del_deflate_vq:
-        vdev->config->del_vq(vb->deflate_vq);
-out_del_inflate_vq:
-        vdev->config->del_vq(vb->inflate_vq);
+out_del_vqs:
+        vdev->config->del_vqs(vdev);
 out_free_vb:
         kfree(vb);
 out:
@@ -264,8 +260,7 @@ static void virtballoon_remove(struct virtio_device *vdev)
         /* Now we reset the device so we can clean up the queues. */
         vdev->config->reset(vdev);
 
-        vdev->config->del_vq(vb->deflate_vq);
-        vdev->config->del_vq(vb->inflate_vq);
+        vdev->config->del_vqs(vdev);
         kfree(vb);
 }
 
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index be4047abd5ba..027f13fbe493 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -276,11 +276,7 @@ static void vp_del_vq(struct virtqueue *vq)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
         struct virtio_pci_vq_info *info = vq->priv;
-        unsigned long flags, size;
-
-        spin_lock_irqsave(&vp_dev->lock, flags);
-        list_del(&info->node);
-        spin_unlock_irqrestore(&vp_dev->lock, flags);
+        unsigned long size;
 
         vring_del_virtqueue(vq);
 
@@ -293,14 +289,41 @@ static void vp_del_vq(struct virtqueue *vq)
         kfree(info);
 }
 
+static void vp_del_vqs(struct virtio_device *vdev)
+{
+        struct virtqueue *vq, *n;
+
+        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+                vp_del_vq(vq);
+}
+
+static int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+                       struct virtqueue *vqs[],
+                       vq_callback_t *callbacks[],
+                       const char *names[])
+{
+        int i;
+
+        for (i = 0; i < nvqs; ++i) {
+                vqs[i] = vp_find_vq(vdev, i, callbacks[i], names[i]);
+                if (IS_ERR(vqs[i]))
+                        goto error;
+        }
+        return 0;
+
+error:
+        vp_del_vqs(vdev);
+        return PTR_ERR(vqs[i]);
+}
+
 static struct virtio_config_ops virtio_pci_config_ops = {
         .get            = vp_get,
         .set            = vp_set,
         .get_status     = vp_get_status,
         .set_status     = vp_set_status,
         .reset          = vp_reset,
-        .find_vq        = vp_find_vq,
-        .del_vq         = vp_del_vq,
+        .find_vqs       = vp_find_vqs,
+        .del_vqs        = vp_del_vqs,
         .get_features   = vp_get_features,
         .finalize_features = vp_finalize_features,
 };
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 9fae274751e0..4cd290c06a88 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -29,6 +29,7 @@
 #define VIRTIO_F_NOTIFY_ON_EMPTY        24
 
 #ifdef __KERNEL__
+#include <linux/err.h>
 #include <linux/virtio.h>
 
 /**
@@ -49,16 +50,26 @@
  * @set_status: write the status byte
  *      vdev: the virtio_device
  *      status: the new status byte
+ * @request_vqs: request the specified number of virtqueues
+ *      vdev: the virtio_device
+ *      max_vqs: the max number of virtqueues we want
+ *      If supplied, must call before any virtqueues are instantiated.
+ *      To modify the max number of virtqueues after request_vqs has been
+ *      called, call free_vqs and then request_vqs with a new value.
+ * @free_vqs: cleanup resources allocated by request_vqs
+ *      vdev: the virtio_device
+ *      If supplied, must call after all virtqueues have been deleted.
  * @reset: reset the device
  *      vdev: the virtio device
  *      After this, status and feature negotiation must be done again
- * @find_vq: find a virtqueue and instantiate it.
+ * @find_vqs: find virtqueues and instantiate them.
  *      vdev: the virtio_device
- *      index: the 0-based virtqueue number in case there's more than one.
- *      callback: the virtqueue callback
- *      name: the virtqueue name (mainly for debugging)
- *      Returns the new virtqueue or ERR_PTR() (eg. -ENOENT).
- * @del_vq: free a virtqueue found by find_vq().
+ *      nvqs: the number of virtqueues to find
+ *      vqs: on success, includes new virtqueues
+ *      callbacks: array of callbacks, for each virtqueue
+ *      names: array of virtqueue names (mainly for debugging)
+ *      Returns 0 on success or error status
+ * @del_vqs: free virtqueues found by find_vqs().
  * @get_features: get the array of feature bits for this device.
  *      vdev: the virtio_device
  *      Returns the first 32 feature bits (all we currently need).
@@ -67,6 +78,7 @@
  *      This gives the final feature bits for the device: it can change
  *      the dev->feature bits if it wants.
  */
+typedef void vq_callback_t(struct virtqueue *);
 struct virtio_config_ops
 {
         void (*get)(struct virtio_device *vdev, unsigned offset,
@@ -76,11 +88,11 @@ struct virtio_config_ops
         u8 (*get_status)(struct virtio_device *vdev);
         void (*set_status)(struct virtio_device *vdev, u8 status);
         void (*reset)(struct virtio_device *vdev);
-        struct virtqueue *(*find_vq)(struct virtio_device *vdev,
-                                     unsigned index,
-                                     void (*callback)(struct virtqueue *),
-                                     const char *name);
-        void (*del_vq)(struct virtqueue *vq);
+        int (*find_vqs)(struct virtio_device *, unsigned nvqs,
+                        struct virtqueue *vqs[],
+                        vq_callback_t *callbacks[],
+                        const char *names[]);
+        void (*del_vqs)(struct virtio_device *);
         u32 (*get_features)(struct virtio_device *vdev);
         void (*finalize_features)(struct virtio_device *vdev);
 };
@@ -128,5 +140,18 @@ static inline int virtio_config_buf(struct virtio_device *vdev,
         vdev->config->get(vdev, offset, buf, len);
         return 0;
 }
+
+static inline
+struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
+                                        vq_callback_t *c, const char *n)
+{
+        vq_callback_t *callbacks[] = { c };
+        const char *names[] = { n };
+        struct virtqueue *vq;
+        int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
+        if (err < 0)
+                return ERR_PTR(err);
+        return vq;
+}
 #endif /* __KERNEL__ */
 #endif /* _LINUX_VIRTIO_CONFIG_H */
diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
index ab8791f9aba8..a49484e67e1d 100644
--- a/net/9p/trans_virtio.c
+++ b/net/9p/trans_virtio.c
@@ -246,7 +246,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)
         chan->vdev = vdev;
 
         /* We expect one virtqueue, for requests. */
-        chan->vq = vdev->config->find_vq(vdev, 0, req_done, "requests");
+        chan->vq = virtio_find_single_vq(vdev, req_done, "requests");
         if (IS_ERR(chan->vq)) {
                 err = PTR_ERR(chan->vq);
                 goto out_free_vq;
@@ -261,7 +261,7 @@ static int p9_virtio_probe(struct virtio_device *vdev)
         return 0;
 
 out_free_vq:
-        vdev->config->del_vq(chan->vq);
+        vdev->config->del_vqs(vdev);
 fail:
         mutex_lock(&virtio_9p_lock);
         chan_index--;
@@ -332,7 +332,7 @@ static void p9_virtio_remove(struct virtio_device *vdev)
         BUG_ON(chan->inuse);
 
         if (chan->initialized) {
-                vdev->config->del_vq(chan->vq);
+                vdev->config->del_vqs(vdev);
                 chan->initialized = false;
         }
 }