queue-4.14/ib-rdmavt-fix-alloc_qpn-warn_on.patch

   1 From 66d7aab68c302abb0e8511eaabd722964a681fb7 Mon Sep 17 00:00:00 2001
   2 From: Mike Marciniszyn <mike.marciniszyn@intel.com>
   3 Date: Fri, 24 May 2019 11:44:38 -0400
   4 Subject: IB/rdmavt: Fix alloc_qpn() WARN_ON()
   5
   6 [ Upstream commit 2abae62a26a265129b364d8c1ef3be55e2c01309 ]
   7
   8 The qpn allocation logic has a WARN_ON() that intends to detect the use of
   9 an index that will introduce bits in the lower order bits of the QOS bits
  10 in the QPN.
  11
  12 Unfortunately, it has the following bugs:
  13 - it misfires when wrapping QPN allocation for non-QOS
  14 - it doesn't correctly detect low order QOS bits (despite the comment)
  15
  16 The WARN_ON() should not be applied to non-QOS (qos_shift == 1).
  17
  18 Additionally, it SHOULD test the qpn bits per the table below:
  19
  20 2 data VLs:   [qp7, qp6, qp5, qp4, qp3, qp2, qp1] ^
  21               [  0,   0,   0,   0,   0,   0, sc0],  qp bit 1 always 0*
  22 3-4 data VLs: [qp7, qp6, qp5, qp4, qp3, qp2, qp1] ^
  23               [  0,   0,   0,   0,   0, sc1, sc0], qp bits [21] always 0
  24 5-8 data VLs: [qp7, qp6, qp5, qp4, qp3, qp2, qp1] ^
  25               [  0,   0,   0,   0, sc2, sc1, sc0] qp bits [321] always 0
  26
  27 Fix by qualifying the warning for qos_shift > 1 and producing the correct
  28 mask to insure the above bits are zero without generating a superfluous
  29 warning.
  30
  31 Fixes: 501edc42446e ("IB/rdmavt: Correct warning during QPN allocation")
  32 Reviewed-by: Kaike Wan <kaike.wan@intel.com>
  33 Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
  34 Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
  35 Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
  36 Signed-off-by: Sasha Levin <sashal@kernel.org>
  37 ---
  38  drivers/infiniband/sw/rdmavt/qp.c | 3 ++-
  39  1 file changed, 2 insertions(+), 1 deletion(-)
  40
  41 diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
  42 index 22df09ae809e..b0309876f4bb 100644
  43 --- a/drivers/infiniband/sw/rdmavt/qp.c
  44 +++ b/drivers/infiniband/sw/rdmavt/qp.c
  45 @@ -412,7 +412,8 @@ static int alloc_qpn(struct rvt_dev_info *rdi, struct rvt_qpn_table *qpt,
  46                         offset = qpt->incr | ((offset & 1) ^ 1);
  47                 }
  48                 /* there can be no set bits in low-order QoS bits */
  49 -               WARN_ON(offset & (BIT(rdi->dparms.qos_shift) - 1));
  50 +               WARN_ON(rdi->dparms.qos_shift > 1 &&
  51 +                       offset & ((BIT(rdi->dparms.qos_shift - 1) - 1) << 1));
  52                 qpn = mk_qpn(qpt, map, offset);
  53         }
  54
  55 --
  56 2.20.1
  57