nfp: use full 40 bits of the NSP buffer address

The NSP default buffer is a piece of NFP memory where additional
command data can be placed.  Its format has been copied from
host buffer, but the PCIe selection bits do not make sense in
this case.  If those get masked out from a NFP address - writes
to random place in the chip memory may be issued and crash the
device.

Even in the general NSP buffer case, it doesn't make sense to have the
PCIe selection bits there anymore. These are unused at the moment, and
when it becomes necessary, the PCIe selection bits should rather be
moved to another register to utilise more bits for the buffer address.

This has never been an issue because the buffer used to be
allocated in memory with less-than-38-bit-long address but that
is about to change.

Fixes: 1a64821c ("nfp: add support for service processor access")
Signed-off-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp.c

@@ -71,10 +71,11 @@
 /* CPP address to retrieve the data from */
 #define NSP_BUFFER		0x10
 #define   NSP_BUFFER_CPP	GENMASK_ULL(63, 40)
-#define   NSP_BUFFER_PCIE	GENMASK_ULL(39, 38)
-#define   NSP_BUFFER_ADDRESS	GENMASK_ULL(37, 0)
+#define   NSP_BUFFER_ADDRESS	GENMASK_ULL(39, 0)
 
 #define NSP_DFLT_BUFFER		0x18
+#define   NSP_DFLT_BUFFER_CPP	GENMASK_ULL(63, 40)
+#define   NSP_DFLT_BUFFER_ADDRESS	GENMASK_ULL(39, 0)
 
 #define NSP_DFLT_BUFFER_CONFIG	0x20
 #define   NSP_DFLT_BUFFER_SIZE_MB	GENMASK_ULL(7, 0)
@@ -427,8 +428,8 @@ __nfp_nsp_command_buf(struct nfp_nsp *nsp, u16 code, u32 option,
 	if (err < 0)
 		return err;
 
-	cpp_id = FIELD_GET(NSP_BUFFER_CPP, reg) << 8;
-	cpp_buf = FIELD_GET(NSP_BUFFER_ADDRESS, reg);
+	cpp_id = FIELD_GET(NSP_DFLT_BUFFER_CPP, reg) << 8;
+	cpp_buf = FIELD_GET(NSP_DFLT_BUFFER_ADDRESS, reg);
 
 	if (in_buf && in_size) {
 		err = nfp_cpp_write(cpp, cpp_id, cpp_buf, in_buf, in_size);