sfc: Fix maximum number of TSO segments and minimum TX queue size

[ Upstream commit 7e6d06f0de3f74ca929441add094518ae332257c ]

Currently an skb requiring TSO may not fit within a minimum-size TX
queue.  The TX queue selected for the skb may stall and trigger the TX
watchdog repeatedly (since the problem skb will be retried after the
TX reset).  This issue is designated as CVE-2012-3412.

Set the maximum number of TSO segments for our devices to 100.  This
should make no difference to behaviour unless the actual MSS is less
than about 700.  Increase the minimum TX queue size accordingly to
allow for 2 worst-case skbs, so that there will definitely be space
to add an skb after we wake a queue.

To avoid invalidating existing configurations, change
efx_ethtool_set_ringparam() to fix up values that are too small rather
than returning -EINVAL.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index d5731f1fe6d67dc3713070ec4e7733f4788cc35a..a6611f1c48f90fcaa0d83ff1532cdc5cbbbf7acb 100644 (file)
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c
@@ -1383,6 +1383,11 @@ static int efx_probe_all(struct efx_nic *efx)
                goto fail2;
        }
 
+       BUILD_BUG_ON(EFX_DEFAULT_DMAQ_SIZE < EFX_RXQ_MIN_ENT);
+       if (WARN_ON(EFX_DEFAULT_DMAQ_SIZE < EFX_TXQ_MIN_ENT(efx))) {
+               rc = -EINVAL;
+               goto fail3;
+       }
        efx->rxq_entries = efx->txq_entries = EFX_DEFAULT_DMAQ_SIZE;
        rc = efx_probe_channels(efx);
        if (rc)
@@ -1973,6 +1978,7 @@ static int efx_register_netdev(struct efx_nic *efx)
        net_dev->irq = efx->pci_dev->irq;
        net_dev->netdev_ops = &efx_netdev_ops;
        SET_ETHTOOL_OPS(net_dev, &efx_ethtool_ops);
+       net_dev->gso_max_segs = EFX_TSO_MAX_SEGS;
 
        /* Clear MAC statistics */
        efx->mac_op->update_stats(efx);

diff --git a/drivers/net/ethernet/sfc/efx.h b/drivers/net/ethernet/sfc/efx.h
index 4764793ed234ce43d222e5d895f15ae69384d9ee..1355245b4da86f873f09421274fa96fd1298b12e 100644 (file)
--- a/drivers/net/ethernet/sfc/efx.h
+++ b/drivers/net/ethernet/sfc/efx.h
@@ -34,6 +34,7 @@ extern netdev_tx_t
 efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb);
 extern void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index);
 extern int efx_setup_tc(struct net_device *net_dev, u8 num_tc);
+extern unsigned int efx_tx_max_skb_descs(struct efx_nic *efx);
 
 /* RX */
 extern int efx_probe_rx_queue(struct efx_rx_queue *rx_queue);
@@ -56,10 +57,15 @@ extern void efx_schedule_slow_fill(struct efx_rx_queue *rx_queue);
 #define EFX_MAX_EVQ_SIZE 16384UL
 #define EFX_MIN_EVQ_SIZE 512UL
 
-/* The smallest [rt]xq_entries that the driver supports. Callers of
- * efx_wake_queue() assume that they can subsequently send at least one
- * skb. Falcon/A1 may require up to three descriptors per skb_frag. */
-#define EFX_MIN_RING_SIZE (roundup_pow_of_two(2 * 3 * MAX_SKB_FRAGS))
+/* Maximum number of TCP segments we support for soft-TSO */
+#define EFX_TSO_MAX_SEGS       100
+
+/* The smallest [rt]xq_entries that the driver supports.  RX minimum
+ * is a bit arbitrary.  For TX, we must have space for at least 2
+ * TSO skbs.
+ */
+#define EFX_RXQ_MIN_ENT                128U
+#define EFX_TXQ_MIN_ENT(efx)   (2 * efx_tx_max_skb_descs(efx))
 
 /* Filters */
 extern int efx_probe_filters(struct efx_nic *efx);

diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
index f3cd96dfa398f01202b7af6d3c63d6f86a5e3c95..90158c913fb068b0cd749937e69281c860f39670 100644 (file)
--- a/drivers/net/ethernet/sfc/ethtool.c
+++ b/drivers/net/ethernet/sfc/ethtool.c
@@ -690,21 +690,27 @@ static int efx_ethtool_set_ringparam(struct net_device *net_dev,
                                     struct ethtool_ringparam *ring)
 {
        struct efx_nic *efx = netdev_priv(net_dev);
+       u32 txq_entries;
 
        if (ring->rx_mini_pending || ring->rx_jumbo_pending ||
            ring->rx_pending > EFX_MAX_DMAQ_SIZE ||
            ring->tx_pending > EFX_MAX_DMAQ_SIZE)
                return -EINVAL;
 
-       if (ring->rx_pending < EFX_MIN_RING_SIZE ||
-           ring->tx_pending < EFX_MIN_RING_SIZE) {
+       if (ring->rx_pending < EFX_RXQ_MIN_ENT) {
                netif_err(efx, drv, efx->net_dev,
-                         "TX and RX queues cannot be smaller than %ld\n",
-                         EFX_MIN_RING_SIZE);
+                         "RX queues cannot be smaller than %u\n",
+                         EFX_RXQ_MIN_ENT);
                return -EINVAL;
        }
 
-       return efx_realloc_channels(efx, ring->rx_pending, ring->tx_pending);
+       txq_entries = max(ring->tx_pending, EFX_TXQ_MIN_ENT(efx));
+       if (txq_entries != ring->tx_pending)
+               netif_warn(efx, drv, efx->net_dev,
+                          "increasing TX queue size to minimum of %u\n",
+                          txq_entries);
+
+       return efx_realloc_channels(efx, ring->rx_pending, txq_entries);
 }
 
 static int efx_ethtool_set_pauseparam(struct net_device *net_dev,

diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h
index 5fb24d3aa3cafba68733d64a4663c5de411a5c31..66ece48003441d968071e0b4a3d09f728d6795d1 100644 (file)
--- a/drivers/net/ethernet/sfc/nic.h
+++ b/drivers/net/ethernet/sfc/nic.h
@@ -65,6 +65,9 @@ enum {
 #define FALCON_GMAC_LOOPBACKS                  \
        (1 << LOOPBACK_GMAC)
 
+/* Alignment of PCIe DMA boundaries (4KB) */
+#define EFX_PAGE_SIZE  4096
+
 /**
  * struct falcon_board_type - board operations and type information
  * @id: Board type id, as found in NVRAM

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index df88c5430f956c6a2752a5dcdd40bcc3fe4066f1..807d515318e91d91bab5802213a35dffb6a4ac2c 100644 (file)
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -115,6 +115,25 @@ efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr)
        return len;
 }
 
+unsigned int efx_tx_max_skb_descs(struct efx_nic *efx)
+{
+       /* Header and payload descriptor for each output segment, plus
+        * one for every input fragment boundary within a segment
+        */
+       unsigned int max_descs = EFX_TSO_MAX_SEGS * 2 + MAX_SKB_FRAGS;
+
+       /* Possibly one more per segment for the alignment workaround */
+       if (EFX_WORKAROUND_5391(efx))
+               max_descs += EFX_TSO_MAX_SEGS;
+
+       /* Possibly more for PCIe page boundaries within input fragments */
+       if (PAGE_SIZE > EFX_PAGE_SIZE)
+               max_descs += max_t(unsigned int, MAX_SKB_FRAGS,
+                                  DIV_ROUND_UP(GSO_MAX_SIZE, EFX_PAGE_SIZE));
+
+       return max_descs;
+}
+
 /*
  * Add a socket buffer to a TX queue
  *