netdev - [PATCH v2 net 4/4] bnx2x: Enlarge the dorq threshold for VFs

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Message-ID: <1402548932-30520-5-git-send-email-yuval.mintz@qlogic.com>
Date:	Thu, 12 Jun 2014 07:55:32 +0300
From:	Yuval Mintz <yuval.mintz@...gic.com>
To:	<davem@...emloft.net>, <netdev@...r.kernel.org>
CC:	<ariel.elior@...gic.com>, Yuval Mintz <yuval.mintz@...gic.com>
Subject: [PATCH v2 net 4/4] bnx2x: Enlarge the dorq threshold for VFs

From: Ariel Elior <ariel.elior@...gic.com>

A malicious VF might try to starve the other VFs & PF by creating
contineous doorbell floods. In order to negate this, HW has a threshold of
doorbells per client, which will stop the client doorbells from arriving
if crossed.

The threshold currently configured for VFs is too low - under extreme traffic
scenarios, it's possible for a VF to reach the threshold and thus for its
fastpath to stop working.

Signed-off-by: Ariel Elior <ariel.elior@...gic.com>
Signed-off-by: Yuval Mintz <yuval.mintz@...gic.com>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
index a93c7af..f7edb42 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_sriov.c
@@ -1071,8 +1071,10 @@ void bnx2x_iov_init_dq(struct bnx2x *bp)
 	REG_WR(bp, DORQ_REG_VF_TYPE_MIN_MCID_0, 0);
 	REG_WR(bp, DORQ_REG_VF_TYPE_MAX_MCID_0, 0x1ffff);
 
-	/* set the VF doorbell threshold */
-	REG_WR(bp, DORQ_REG_VF_USAGE_CT_LIMIT, 4);
+	/* set the VF doorbell threshold. This threshold represents the amount
+	 * of doorbells allowed in the main DORQ fifo for a specific VF.
+	 */
+	REG_WR(bp, DORQ_REG_VF_USAGE_CT_LIMIT, 64);
 }
 
 void bnx2x_iov_init_dmae(struct bnx2x *bp)
-- 
1.8.1.4

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