From: Jakub Kicinski <jakub.kicinski@netronome.com>
Date: Sun, 28 May 2017 17:52:59 -0700
Subject: nfp: support variable NSP response lengths
Patch-mainline: v4.13-rc1
Git-commit: a87853f383afd6cb1cbda982d895e9cadf435098
References: bsc#1055968

We want to support extendable commands, where newer versions
of the management FW may provide more information.  Zero out
the communication buffer before passing control to NSP.  This
way if management FW is old and only fills in first N bytes,
the remaining ones will be zeros which extended ABI fields
should reserve as not supported/not available.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.c
+++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.c
@@ -419,6 +419,14 @@ static int nfp_nsp_command_buf(struct nf
 		if (err < 0)
 			return err;
 	}
+	/* Zero out remaining part of the buffer */
+	if (out_buf && out_size && out_size > in_size) {
+		memset(out_buf, 0, out_size - in_size);
+		err = nfp_cpp_write(cpp, cpp_id, cpp_buf + in_size,
+				    out_buf, out_size - in_size);
+		if (err < 0)
+			return err;
+	}
 
 	ret = nfp_nsp_command(nsp, code, option, cpp_id, cpp_buf);
 	if (ret < 0)