[PATCH] s390: qdio V=V pass-through

New feature V=V qdio pass-through.

QDIO and HiperSockets processing in z/VM V=V guest environments (as well as
V=R with z/VM running in LPAR mode) requires shadowing of all QDIO
architecture queue elements.  Especially the shadowing of SBALs and SLSBs
structures in the hypervisor, and the need to issue SIGA SYNC operations to
observe state changes, eventually causes significant CPU processing overhead
in the hypervisor.

The QDIO pass-through support for V=V guests avoids the shadowing of SBALs and
SLSBs.  This significantly reduces the hypervisor overhead for QDIO based I/O.

Signed-off-by: Frank Pavlic <pavlic@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/asm-s390/qdio.h b/include/asm-s390/qdio.h
index 0ddf0a8ef8d..7bc15f0231d 100644
--- a/include/asm-s390/qdio.h
+++ b/include/asm-s390/qdio.h
@@ -195,12 +195,14 @@ struct qdr {
 /*
  * queue information block (QIB)
  */
-#define QIB_AC_INBOUND_PCI_SUPPORTED 0x80
-#define QIB_AC_OUTBOUND_PCI_SUPPORTED 0x40
+#define QIB_AC_INBOUND_PCI_SUPPORTED    0x80
+#define QIB_AC_OUTBOUND_PCI_SUPPORTED   0x40
+#define QIB_RFLAGS_ENABLE_QEBSM         0x80
+
 struct qib {
         unsigned int  qfmt    :  8;     /* queue format */
         unsigned int  pfmt    :  8;     /* impl. dep. parameter format */
-        unsigned int  res1    :  8;     /* reserved */
+        unsigned int  rflags  :  8;     /* QEBSM */
         unsigned int  ac      :  8;     /* adapter characteristics */
         unsigned int  res2;             /* reserved */
 #ifdef QDIO_32_BIT