ntb_transport: Fix bug with max_mw_size parameter

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: e26a584 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Signed-off-by: Logan Gunthorpe <[email protected]>
Acked-by: Allen Hubbe <[email protected]>
Cc: Dave Jiang <[email protected]>
Signed-off-by: Jon Mason <[email protected]>

Author: lsgunth

drivers/ntb/ntb_transport.c

@@ -1003,6 +1003,9 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt,
 	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);