[Devel] [PATCH RHEL7 COMMIT] ms/ixgbe: Fix packet corruption due to missing DMA sync

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-1160.80.1.vz7.190.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.80.1.vz7.190.1
------>
commit f696a7992dfe55b79ad1fdb255dd312e36048584
Author: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
Date:   Tue Nov 29 12:55:54 2022 +0200

    ms/ixgbe: Fix packet corruption due to missing DMA sync
    
      When receiving a packet with multiple fragments, hardware may still
      touch the first fragment until the entire packet has been received. The
      driver therefore keeps the first fragment mapped for DMA until end of
      packet has been asserted, and delays its dma_sync call until then.
    
      The driver tries to fit multiple receive buffers on one page. When using
      3K receive buffers (e.g. using Jumbo frames and legacy-rx is turned
      off/build_skb is being used) on an architecture with 4K pages, the
      driver allocates an order 1 compound page and uses one page per receive
      buffer. To determine the correct offset for a delayed DMA sync of the
      first fragment of a multi-fragment packet, the driver then cannot just
      use PAGE_MASK on the DMA address but has to construct a mask based on
      the actual size of the backing page.
    
      Using PAGE_MASK in the 3K RX buffer/4K page architecture configuration
      will always sync the first page of a compound page. With the SWIOTLB
      enabled this can lead to corrupted packets (zeroed out first fragment,
      re-used garbage from another packet) and various consequences, such as
      slow/stalling data transfers and connection resets. For example, testing
      on a link with MTU exceeding 3058 bytes on a host with SWIOTLB enabled
      (e.g. "iommu=soft swiotlb=262144,force") TCP transfers quickly fizzle
      out without this patch.
    
      Cc: stable at vger.kernel.org
      Fixes: 0c5661ecc5dd7 ("ixgbe: fix crash in build_skb Rx code path")
      Signed-off-by: Markus Boehme <markubo at amazon.com>
      Tested-by: Tony Brelinski <tonyx.brelinski at intel.com>
      Signed-off-by: Tony Nguyen <anthony.l.nguyen at intel.com>
      Signed-off-by: David S. Miller <davem at davemloft.net>
    
    (mainstream commit 09cfae9f13d51700b0fecf591dcd658fc5375428)
    https://jira.sw.ru/browse/PSBM-142789
    Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index b39a1b477b24..725ddb36b846 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -1886,7 +1886,8 @@ static void ixgbe_dma_sync_frag(struct ixgbe_ring *rx_ring,
 				     DMA_FROM_DEVICE,
 				     &attrs);
 	} else if (ring_uses_build_skb(rx_ring)) {
-		unsigned long offset = (unsigned long)(skb->data) & ~PAGE_MASK;
+		unsigned long mask = (unsigned long)ixgbe_rx_pg_size(rx_ring) - 1;
+		unsigned long offset = (unsigned long)(skb->data) & mask;
 
 		dma_sync_single_range_for_cpu(rx_ring->dev,
 					      IXGBE_CB(skb)->dma,