svn commit: r280375 - head/sys/dev/sfxge/common

[Andrew Rybchenko]

Author: arybchik
Date: Mon Mar 23 15:45:39 2015
New Revision: 280375
URL: https://svnweb.freebsd.org/changeset/base/280375

Log:
  sfxge: add barriers to BAR write macros
  
  In theory the barriers are required to cope with write combining and
  reordering. Two barriers are added (sometimes merged to one):
   1. Before the first write to guarantee that previous writes to the region
      have been done
   2. Before the last write to guarantee that write to the last dword/qword is
      done after previous writes
  Barriers are inserted before in the assumption that it is better to
  postpone barriers as much as it is possible (more chances that the
  operation has already been already done and barrier does not stall CPU).
  
  On x86 and amd64 bus space write barriers are just compiler memory barriers
  which are definitely required.
  
  Sponsored by:   Solarflare Communications, Inc.
  Differential Revision: https://reviews.freebsd.org/D2077

Modified:
  head/sys/dev/sfxge/common/efsys.h

Modified: head/sys/dev/sfxge/common/efsys.h
==============================================================================
--- head/sys/dev/sfxge/common/efsys.h	Mon Mar 23 15:44:17 2015	(r280374)
+++ head/sys/dev/sfxge/common/efsys.h	Mon Mar 23 15:45:39 2015	(r280375)
@@ -786,6 +786,14 @@ typedef struct efsys_bar_s {
 		EFSYS_PROBE2(bar_writed, unsigned int, (_offset),	\
 		    uint32_t, (_edp)->ed_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the dword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_dword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_edp)->ed_u32[0]);			\
@@ -809,6 +817,14 @@ typedef struct efsys_bar_s {
 		    uint32_t, (_eqp)->eq_u32[1],			\
 		    uint32_t, (_eqp)->eq_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the qword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_qword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_8((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eqp)->eq_u64[0]);			\
@@ -829,9 +845,25 @@ typedef struct efsys_bar_s {
 		    uint32_t, (_eqp)->eq_u32[1],			\
 		    uint32_t, (_eqp)->eq_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the qword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the last write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_qword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eqp)->eq_u32[0]);			\
+		/*							\
+		 * It should be guaranteed that the last dword comes	\
+		 * the last, so barrier entire qword to be sure that	\
+		 * neither above nor below writes are reordered.	\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_qword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 4, (_eqp)->eq_u32[1]);			\
@@ -858,9 +890,25 @@ typedef struct efsys_bar_s {
 		    uint32_t, (_eop)->eo_u32[1],			\
 		    uint32_t, (_eop)->eo_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the oword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the last write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_8((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eop)->eo_u64[0]);			\
+		/*							\
+		 * It should be guaranteed that the last qword comes	\
+		 * the last, so barrier entire oword to be sure that	\
+		 * neither above nor below writes are reordered.	\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_8((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 8, (_eop)->eo_u64[1]);			\
@@ -888,6 +936,14 @@ typedef struct efsys_bar_s {
 		    uint32_t, (_eop)->eo_u32[1],			\
 		    uint32_t, (_eop)->eo_u32[0]);			\
 									\
+		/*							\
+		 * Make sure that previous writes to the oword have	\
+		 * been done. It should be cheaper than barrier just	\
+		 * after the last write below.				\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset), (_eop)->eo_u32[0]);			\
@@ -897,6 +953,14 @@ typedef struct efsys_bar_s {
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 8, (_eop)->eo_u32[2]);			\
+		/*							\
+		 * It should be guaranteed that the last dword comes	\
+		 * the last, so barrier entire oword to be sure that	\
+		 * neither above nor below writes are reordered.	\
+		 */							\
+		bus_space_barrier((_esbp)->esb_tag, (_esbp)->esb_handle,\
+		    (_offset), sizeof (efx_oword_t),			\
+		    BUS_SPACE_BARRIER_WRITE);				\
 		bus_space_write_stream_4((_esbp)->esb_tag,		\
 		    (_esbp)->esb_handle,				\
 		    (_offset) + 12, (_eop)->eo_u32[3]);			\