svn commit: r320972 - head/sys/dev/ixl

[Eric Joyner]

Author: erj
Date: Thu Jul 13 22:12:41 2017
New Revision: 320972
URL: https://svnweb.freebsd.org/changeset/base/320972

Log:
  ixl(4)/ixlv(4): Stop leaking every busdma entry in receive path
  
  From Brett:
  
  In short, busdma maps for received packets were not being unloaded in the
  interrupt handler before the packets were passed up the network stack. The fix
  was to add a busdma sync and unload for the two receive maps.
  
  This bug is significant for certain busdma providers, for example IOMMUs,
  where not unloading the maps means that 1) the IOMMU mappings that allow the
  NIC to DMA the received packets into host memory stay open indefinitely,
  potentially violating a desired security policy, and 2) resources such as
  device address space addresses and host memory for bookkeeping are never freed.
  
  Without an IOMMU or bounce buffering enabled for the ixl device, I don't think
  adding these calls will have any significant performance impact. With the
  IOMMU enabled, I have noticed a performance impact on the receive side, which
  is expected.
  
  Submitted by:	Brett Gutstein <bgutstein at rice.edu>
  Reviewed by:	erj@
  MFC after:	1 week

Modified:
  head/sys/dev/ixl/ixl_txrx.c

Modified: head/sys/dev/ixl/ixl_txrx.c
==============================================================================
--- head/sys/dev/ixl/ixl_txrx.c	Thu Jul 13 22:01:38 2017	(r320971)
+++ head/sys/dev/ixl/ixl_txrx.c	Thu Jul 13 22:12:41 2017	(r320972)
@@ -1578,6 +1578,18 @@ ixl_rxeof(struct ixl_queue *que, int count)
 		else
 			vtag = 0;
 
+		/* Remove device access to the rx buffers. */
+		if (rbuf->m_head != NULL) {
+			bus_dmamap_sync(rxr->htag, rbuf->hmap,
+			    BUS_DMASYNC_POSTREAD);
+			bus_dmamap_unload(rxr->htag, rbuf->hmap);
+		}
+		if (rbuf->m_pack != NULL) {
+			bus_dmamap_sync(rxr->ptag, rbuf->pmap,
+			    BUS_DMASYNC_POSTREAD);
+			bus_dmamap_unload(rxr->ptag, rbuf->pmap);
+		}
+
 		/*
 		** Make sure bad packets are discarded,
 		** note that only EOP descriptor has valid