ibmveth: enable driver for CMO

Enable ibmveth for Cooperative Memory Overcommitment (CMO). For this driver
it means calculating a desired amount of IO memory based on the current MTU
and updating this value with the bus when MTU changes occur. Because DMA
mappings can fail, we have added a bounce buffer for temporary cases where
the driver can not map IO memory for the buffer pool.

The following changes are made to enable the driver for CMO:
* DMA mapping errors will not result in error messages if entitlement has
been exceeded and resources were not available.
* DMA mapping errors are handled gracefully, ibmveth_replenish_buffer_pool()
is corrected to check the return from dma_map_single and fail gracefully.
* The driver will have a get_desired_dma function defined to function
in a CMO environment.
* When the MTU is changed, the driver will update the device IO entitlement

Signed-off-by: Robert Jennings <[e-mail]>
Signed-off-by: Brian King <[e-mail]>
Signed-off-by: Santiago Leon <[e-mail]>
Acked-by: Paul Mackerras <[e-mail]>
Signed-off-by: Benjamin Herrenschmidt <[e-mail]>

drivers/net/ibmveth.c

···
 */
 
 #include <linux/module.h>
+#include <linux/moduleparam.h>
 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/ioport.h>
···
 #include <asm/hvcall.h>
 #include <asm/atomic.h>
 #include <asm/vio.h>
+#include <asm/iommu.h>
 #include <asm/uaccess.h>
+#include <asm/firmware.h>
 #include <linux/seq_file.h>
 
 #include "ibmveth.h"
···
 static void ibmveth_proc_unregister_adapter(struct ibmveth_adapter *adapter);
 static irqreturn_t ibmveth_interrupt(int irq, void *dev_instance);
 static void ibmveth_rxq_harvest_buffer(struct ibmveth_adapter *adapter);
+static unsigned long ibmveth_get_desired_dma(struct vio_dev *vdev);
 static struct kobj_type ktype_veth_pool;
+
 
 #ifdef CONFIG_PROC_FS
 #define IBMVETH_PROC_DIR "ibmveth"
···
 	u32 i;
 	u32 count = pool->size - atomic_read(&pool->available);
 	u32 buffers_added = 0;
+	struct sk_buff *skb;
+	unsigned int free_index, index;
+	u64 correlator;
+	unsigned long lpar_rc;
+	dma_addr_t dma_addr;
 
 	mb();
 
 	for(i = 0; i < count; ++i) {
-		struct sk_buff *skb;
-		unsigned int free_index, index;
-		u64 correlator;
 		union ibmveth_buf_desc desc;
-		unsigned long lpar_rc;
-		dma_addr_t dma_addr;
 
 		skb = alloc_skb(pool->buff_size, GFP_ATOMIC);
 
···
 		dma_addr = dma_map_single(&adapter->vdev->dev, skb->data,
 				pool->buff_size, DMA_FROM_DEVICE);
 
+		if (dma_mapping_error(dma_addr))
+			goto failure;
+
 		pool->free_map[free_index] = IBM_VETH_INVALID_MAP;
 		pool->dma_addr[index] = dma_addr;
 		pool->skbuff[index] = skb;
···
 
 		lpar_rc = h_add_logical_lan_buffer(adapter->vdev->unit_address, desc.desc);
 
-		if(lpar_rc != H_SUCCESS) {
-			pool->free_map[free_index] = index;
-			pool->skbuff[index] = NULL;
-			if (pool->consumer_index == 0)
-				pool->consumer_index = pool->size - 1;
-			else
-				pool->consumer_index--;
-			dma_unmap_single(&adapter->vdev->dev,
-					pool->dma_addr[index], pool->buff_size,
-					DMA_FROM_DEVICE);
-			dev_kfree_skb_any(skb);
-			adapter->replenish_add_buff_failure++;
-			break;
-		} else {
+		if (lpar_rc != H_SUCCESS)
+			goto failure;
+		else {
 			buffers_added++;
 			adapter->replenish_add_buff_success++;
 		}
 	}
+
+	mb();
+	atomic_add(buffers_added, &(pool->available));
+	return;
+
+failure:
+	pool->free_map[free_index] = index;
+	pool->skbuff[index] = NULL;
+	if (pool->consumer_index == 0)
+		pool->consumer_index = pool->size - 1;
+	else
+		pool->consumer_index--;
+	if (!dma_mapping_error(dma_addr))
+		dma_unmap_single(&adapter->vdev->dev,
+		                 pool->dma_addr[index], pool->buff_size,
+		                 DMA_FROM_DEVICE);
+	dev_kfree_skb_any(skb);
+	adapter->replenish_add_buff_failure++;
 
 	mb();
 	atomic_add(buffers_added, &(pool->available));
···
 
 	adapter->replenish_task_cycles++;
 
-	for(i = 0; i < IbmVethNumBufferPools; i++)
+	for (i = (IbmVethNumBufferPools - 1); i >= 0; i--)
 		if(adapter->rx_buff_pool[i].active)
 			ibmveth_replenish_buffer_pool(adapter,
 						     &adapter->rx_buff_pool[i]);
···
 		if (adapter->rx_buff_pool[i].active)
 			ibmveth_free_buffer_pool(adapter,
 						 &adapter->rx_buff_pool[i]);
+
+	if (adapter->bounce_buffer != NULL) {
+		if (!dma_mapping_error(adapter->bounce_buffer_dma)) {
+			dma_unmap_single(&adapter->vdev->dev,
+					adapter->bounce_buffer_dma,
+					adapter->netdev->mtu + IBMVETH_BUFF_OH,
+					DMA_BIDIRECTIONAL);
+			adapter->bounce_buffer_dma = DMA_ERROR_CODE;
+		}
+		kfree(adapter->bounce_buffer);
+		adapter->bounce_buffer = NULL;
+	}
 }
 
 static int ibmveth_register_logical_lan(struct ibmveth_adapter *adapter,
···
 		ibmveth_cleanup(adapter);
 		napi_disable(&adapter->napi);
 		return rc;
+	}
+
+	adapter->bounce_buffer =
+	    kmalloc(netdev->mtu + IBMVETH_BUFF_OH, GFP_KERNEL);
+	if (!adapter->bounce_buffer) {
+		ibmveth_error_printk("unable to allocate bounce buffer\n");
+		ibmveth_cleanup(adapter);
+		napi_disable(&adapter->napi);
+		return -ENOMEM;
+	}
+	adapter->bounce_buffer_dma =
+	    dma_map_single(&adapter->vdev->dev, adapter->bounce_buffer,
+			   netdev->mtu + IBMVETH_BUFF_OH, DMA_BIDIRECTIONAL);
+	if (dma_mapping_error(adapter->bounce_buffer_dma)) {
+		ibmveth_error_printk("unable to map bounce buffer\n");
+		ibmveth_cleanup(adapter);
+		napi_disable(&adapter->napi);
+		return -ENOMEM;
 	}
 
 	ibmveth_debug_printk("initial replenish cycle\n");
···
 	unsigned int tx_packets = 0;
 	unsigned int tx_send_failed = 0;
 	unsigned int tx_map_failed = 0;
+	int used_bounce = 0;
+	unsigned long data_dma_addr;
 
 	desc.fields.flags_len = IBMVETH_BUF_VALID | skb->len;
-	desc.fields.address = dma_map_single(&adapter->vdev->dev, skb->data,
-					     skb->len, DMA_TO_DEVICE);
+	data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data,
+				       skb->len, DMA_TO_DEVICE);
 
 	if (skb->ip_summed == CHECKSUM_PARTIAL &&
 	    ip_hdr(skb)->protocol != IPPROTO_TCP && skb_checksum_help(skb)) {
···
 		buf[1] = 0;
 	}
 
-	if (dma_mapping_error(desc.fields.address)) {
-		ibmveth_error_printk("tx: unable to map xmit buffer\n");
+	if (dma_mapping_error(data_dma_addr)) {
+		if (!firmware_has_feature(FW_FEATURE_CMO))
+			ibmveth_error_printk("tx: unable to map xmit buffer\n");
+		skb_copy_from_linear_data(skb, adapter->bounce_buffer,
+					  skb->len);
+		desc.fields.address = adapter->bounce_buffer_dma;
 		tx_map_failed++;
-		tx_dropped++;
-		goto out;
-	}
+		used_bounce = 1;
+	} else
+		desc.fields.address = data_dma_addr;
 
 	/* send the frame. Arbitrarily set retrycount to 1024 */
 	correlator = 0;
···
 		netdev->trans_start = jiffies;
 	}
 
-	dma_unmap_single(&adapter->vdev->dev, desc.fields.address,
-			 skb->len, DMA_TO_DEVICE);
+	if (!used_bounce)
+		dma_unmap_single(&adapter->vdev->dev, data_dma_addr,
+				 skb->len, DMA_TO_DEVICE);
 
 out:	spin_lock_irqsave(&adapter->stats_lock, flags);
 	netdev->stats.tx_dropped += tx_dropped;
···
 static int ibmveth_change_mtu(struct net_device *dev, int new_mtu)
 {
 	struct ibmveth_adapter *adapter = dev->priv;
+	struct vio_dev *viodev = adapter->vdev;
 	int new_mtu_oh = new_mtu + IBMVETH_BUFF_OH;
-	int i, rc;
+	int i;
 
 	if (new_mtu < IBMVETH_MAX_MTU)
 		return -EINVAL;
···
 				ibmveth_close(adapter->netdev);
 				adapter->pool_config = 0;
 				dev->mtu = new_mtu;
-				if ((rc = ibmveth_open(adapter->netdev)))
-					return rc;
-			} else
-				dev->mtu = new_mtu;
+				vio_cmo_set_dev_desired(viodev,
+						ibmveth_get_desired_dma
+						(viodev));
+				return ibmveth_open(adapter->netdev);
+			}
+			dev->mtu = new_mtu;
+			vio_cmo_set_dev_desired(viodev,
+						ibmveth_get_desired_dma
+						(viodev));
 			return 0;
 		}
 	}
···
 	ibmveth_interrupt(dev->irq, dev);
 }
 #endif
+
+/**
+ * ibmveth_get_desired_dma - Calculate IO memory desired by the driver
+ *
+ * @vdev: struct vio_dev for the device whose desired IO mem is to be returned
+ *
+ * Return value:
+ *	Number of bytes of IO data the driver will need to perform well.
+ */
+static unsigned long ibmveth_get_desired_dma(struct vio_dev *vdev)
+{
+	struct net_device *netdev = dev_get_drvdata(&vdev->dev);
+	struct ibmveth_adapter *adapter;
+	unsigned long ret;
+	int i;
+	int rxqentries = 1;
+
+	/* netdev inits at probe time along with the structures we need below*/
+	if (netdev == NULL)
+		return IOMMU_PAGE_ALIGN(IBMVETH_IO_ENTITLEMENT_DEFAULT);
+
+	adapter = netdev_priv(netdev);
+
+	ret = IBMVETH_BUFF_LIST_SIZE + IBMVETH_FILT_LIST_SIZE;
+	ret += IOMMU_PAGE_ALIGN(netdev->mtu);
+
+	for (i = 0; i < IbmVethNumBufferPools; i++) {
+		/* add the size of the active receive buffers */
+		if (adapter->rx_buff_pool[i].active)
+			ret +=
+			    adapter->rx_buff_pool[i].size *
+			    IOMMU_PAGE_ALIGN(adapter->rx_buff_pool[i].
+			            buff_size);
+		rxqentries += adapter->rx_buff_pool[i].size;
+	}
+	/* add the size of the receive queue entries */
+	ret += IOMMU_PAGE_ALIGN(rxqentries * sizeof(struct ibmveth_rx_q_entry));
+
+	return ret;
+}
 
 static int __devinit ibmveth_probe(struct vio_dev *dev, const struct vio_device_id *id)
 {
···
 	ibmveth_proc_unregister_adapter(adapter);
 
 	free_netdev(netdev);
+	dev_set_drvdata(&dev->dev, NULL);
+
 	return 0;
 }
 
···
 	.id_table	= ibmveth_device_table,
 	.probe		= ibmveth_probe,
 	.remove		= ibmveth_remove,
+	.get_desired_dma = ibmveth_get_desired_dma,
 	.driver		= {
 		.name	= ibmveth_driver_name,
 		.owner	= THIS_MODULE,

drivers/net/ibmveth.h

···
   plpar_hcall_norets(H_CHANGE_LOGICAL_LAN_MAC, ua, mac)
 
 #define IbmVethNumBufferPools 5
+#define IBMVETH_IO_ENTITLEMENT_DEFAULT 4243456 /* MTU of 1500 needs 4.2Mb */
 #define IBMVETH_BUFF_OH 22 /* Overhead: 14 ethernet header + 8 opaque handle */
 #define IBMVETH_MAX_MTU 68
 #define IBMVETH_MAX_POOL_COUNT 4096
+#define IBMVETH_BUFF_LIST_SIZE 4096
+#define IBMVETH_FILT_LIST_SIZE 4096
 #define IBMVETH_MAX_BUF_SIZE (1024 * 128)
 
 static int pool_size[] = { 512, 1024 * 2, 1024 * 16, 1024 * 32, 1024 * 64 };
···
     struct ibmveth_rx_q rx_queue;
     int pool_config;
     int rx_csum;
+    void *bounce_buffer;
+    dma_addr_t bounce_buffer_dma;
 
     /* adapter specific stats */
     u64 replenish_task_cycles;