xenbus_client: Extend interface to support multi-page ring

Originally Xen PV drivers only use single-page ring to pass along
information. This might limit the throughput between frontend and
backend.

The patch extends Xenbus driver to support multi-page ring, which in
general should improve throughput if ring is the bottleneck. Changes to
various frontend / backend to adapt to the new interface are also
included.

Affected Xen drivers:
* blkfront/back
* netfront/back
* pcifront/back
* scsifront/back
* vtpmfront

The interface is documented, as before, in xenbus_client.c.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

11 files changed, 324 insertions, 125 deletions

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index e3afe97280b1..ff3025922c14 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -193,7 +193,7 @@ fail:
         return ERR_PTR(-ENOMEM);
 }
 
-static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
+static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t gref,
                          unsigned int evtchn)
 {
         int err;
@@ -202,7 +202,8 @@ static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
         if (blkif->irq)
                 return 0;
 
-        err = xenbus_map_ring_valloc(blkif->be->dev, shared_page, &blkif->blk_ring);
+        err = xenbus_map_ring_valloc(blkif->be->dev, &gref, 1,
+                                     &blkif->blk_ring);
         if (err < 0)
                 return err;
 
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 37779e4c4585..2c61cf8c6f61 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1245,6 +1245,7 @@ static int setup_blkring(struct xenbus_device *dev,
                          struct blkfront_info *info)
 {
         struct blkif_sring *sring;
+        grant_ref_t gref;
         int err;
 
         info->ring_ref = GRANT_INVALID_REF;
@@ -1257,13 +1258,13 @@ static int setup_blkring(struct xenbus_device *dev,
         SHARED_RING_INIT(sring);
         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 
-        err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
+        err = xenbus_grant_ring(dev, info->ring.sring, 1, &gref);
         if (err < 0) {
                 free_page((unsigned long)sring);
                 info->ring.sring = NULL;
                 goto fail;
         }
-        info->ring_ref = err;
+        info->ring_ref = gref;
 
         err = xenbus_alloc_evtchn(dev, &info->evtchn);
         if (err)
diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
index c3b4f5a5ac10..3111f2778079 100644
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -193,6 +193,7 @@ static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
         struct xenbus_transaction xbt;
         const char *message = NULL;
         int rv;
+        grant_ref_t gref;
 
         priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
         if (!priv->shr) {
@@ -200,11 +201,11 @@ static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
                 return -ENOMEM;
         }
 
-        rv = xenbus_grant_ring(dev, virt_to_mfn(priv->shr));
+        rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref);
         if (rv < 0)
                 return rv;
 
-        priv->ring_ref = rv;
+        priv->ring_ref = gref;
 
         rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
         if (rv)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index cab9f5257f57..99a49479843d 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1781,7 +1781,7 @@ int xenvif_map_frontend_rings(struct xenvif_queue *queue,
         int err = -ENOMEM;
 
         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
-                                     tx_ring_ref, &addr);
+                                     &tx_ring_ref, 1, &addr);
         if (err)
                 goto err;
 
@@ -1789,7 +1789,7 @@ int xenvif_map_frontend_rings(struct xenvif_queue *queue,
         BACK_RING_INIT(&queue->tx, txs, PAGE_SIZE);
 
         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(queue->vif),
-                                     rx_ring_ref, &addr);
+                                     &rx_ring_ref, 1, &addr);
         if (err)
                 goto err;
 
diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index e9b960f0ff32..13f5e7ff4bb5 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1486,6 +1486,7 @@ static int setup_netfront(struct xenbus_device *dev,
 {
         struct xen_netif_tx_sring *txs;
         struct xen_netif_rx_sring *rxs;
+        grant_ref_t gref;
         int err;
 
         queue->tx_ring_ref = GRANT_INVALID_REF;
@@ -1502,10 +1503,10 @@ static int setup_netfront(struct xenbus_device *dev,
         SHARED_RING_INIT(txs);
         FRONT_RING_INIT(&queue->tx, txs, PAGE_SIZE);
 
-        err = xenbus_grant_ring(dev, virt_to_mfn(txs));
+        err = xenbus_grant_ring(dev, txs, 1, &gref);
         if (err < 0)
                 goto grant_tx_ring_fail;
-        queue->tx_ring_ref = err;
+        queue->tx_ring_ref = gref;
 
         rxs = (struct xen_netif_rx_sring *)get_zeroed_page(GFP_NOIO | __GFP_HIGH);
         if (!rxs) {
@@ -1516,10 +1517,10 @@ static int setup_netfront(struct xenbus_device *dev,
         SHARED_RING_INIT(rxs);
         FRONT_RING_INIT(&queue->rx, rxs, PAGE_SIZE);
 
-        err = xenbus_grant_ring(dev, virt_to_mfn(rxs));
+        err = xenbus_grant_ring(dev, rxs, 1, &gref);
         if (err < 0)
                 goto grant_rx_ring_fail;
-        queue->rx_ring_ref = err;
+        queue->rx_ring_ref = gref;
 
         if (feature_split_evtchn)
                 err = setup_netfront_split(queue);
diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index b1ffebec9b9e..7cfd2db02deb 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -777,12 +777,13 @@ static int pcifront_publish_info(struct pcifront_device *pdev)
 {
         int err = 0;
         struct xenbus_transaction trans;
+        grant_ref_t gref;
 
-        err = xenbus_grant_ring(pdev->xdev, virt_to_mfn(pdev->sh_info));
+        err = xenbus_grant_ring(pdev->xdev, pdev->sh_info, 1, &gref);