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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Logan Gunthorpe <logang@deltatee.com>,
        Allen Hubbe <Allen.Hubbe@dell.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Jon Mason <jdmason@kudzu.us>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.4 045/268] ntb_transport: Fix bug with max_mw_size parameter
Date:   Mon, 28 May 2018 12:00:19 +0200
Message-Id: <20180528100207.129185851@linuxfoundation.org>
In-Reply-To: <20180528100202.045206534@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Logan Gunthorpe <logang@deltatee.com>

[ Upstream commit cbd27448faff4843ac4b66cc71445a10623ff48d ]

When using the max_mw_size parameter of ntb_transport to limit the size of
the Memory windows, communication cannot be established and the queues
freeze.

This is because the mw_size that's reported to the peer is correctly
limited but the size used locally is not. So the MW is initialized
with a buffer smaller than the window but the TX side is using the
full window. This means the TX side will be writing to a region of the
window that points nowhere.

This is easily fixed by applying the same limit to tx_size in
ntb_transport_init_queue().

Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/ntb/ntb_transport.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/ntb/ntb_transport.c
+++ b/drivers/ntb/ntb_transport.c
@@ -955,6 +955,9 @@ static int ntb_transport_init_queue(stru
 	mw_base = nt->mw_vec[mw_num].phys_addr;
 	mw_size = nt->mw_vec[mw_num].phys_size;
 
+	if (max_mw_size && mw_size > max_mw_size)
+		mw_size = max_mw_size;
+
 	tx_size = (unsigned int)mw_size / num_qps_mw;
 	qp_offset = tx_size * (qp_num / mw_count);