sfc: Use fixed-size buffers for MCDI NVRAM requests

The low-level MCDI code always uses 32-bit MMIO operations, and
callers must pad input and output buffers to multiples of 4 bytes.
The MCDI NVRAM functions are not doing this.  Also, their buffers are
declared as variable-length arrays with no explicit maximum length.

Switch to a fixed buffer size based on the chunk size used by the
MTD driver (which is a multiple of 4).

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 7 insertions, 6 deletions

diff --git a/drivers/net/sfc/mcdi.c b/drivers/net/sfc/mcdi.c
index 0d4eba7266ec..9f035b9f0350 100644
--- a/drivers/net/sfc/mcdi.c
+++ b/drivers/net/sfc/mcdi.c
@@ -804,7 +804,7 @@ int efx_mcdi_nvram_read(struct efx_nic *efx, unsigned int type,
                         loff_t offset, u8 *buffer, size_t length)
 {
         u8 inbuf[MC_CMD_NVRAM_READ_IN_LEN];
-        u8 outbuf[MC_CMD_NVRAM_READ_OUT_LEN(length)];
+        u8 outbuf[MC_CMD_NVRAM_READ_OUT_LEN(EFX_MCDI_NVRAM_LEN_MAX)];
         size_t outlen;
         int rc;
 
@@ -828,7 +828,7 @@ fail:
 int efx_mcdi_nvram_write(struct efx_nic *efx, unsigned int type,
                            loff_t offset, const u8 *buffer, size_t length)
 {
-        u8 inbuf[MC_CMD_NVRAM_WRITE_IN_LEN(length)];
+        u8 inbuf[MC_CMD_NVRAM_WRITE_IN_LEN(EFX_MCDI_NVRAM_LEN_MAX)];
         int rc;
 
         MCDI_SET_DWORD(inbuf, NVRAM_WRITE_IN_TYPE, type);
@@ -838,7 +838,8 @@ int efx_mcdi_nvram_write(struct efx_nic *efx, unsigned int type,
 
         BUILD_BUG_ON(MC_CMD_NVRAM_WRITE_OUT_LEN != 0);
 
-        rc = efx_mcdi_rpc(efx, MC_CMD_NVRAM_WRITE, inbuf, sizeof(inbuf),
+        rc = efx_mcdi_rpc(efx, MC_CMD_NVRAM_WRITE, inbuf,
+                          ALIGN(MC_CMD_NVRAM_WRITE_IN_LEN(length), 4),
                           NULL, 0, NULL);
         if (rc)
                 goto fail;
diff --git a/drivers/net/sfc/mcdi.h b/drivers/net/sfc/mcdi.h
index de916728c2e3..10ce98f4c0fb 100644
--- a/drivers/net/sfc/mcdi.h
+++ b/drivers/net/sfc/mcdi.h
@@ -111,6 +111,7 @@ extern int efx_mcdi_nvram_read(struct efx_nic *efx, unsigned int type,
 extern int efx_mcdi_nvram_write(struct efx_nic *efx, unsigned int type,
                                 loff_t offset, const u8 *buffer,
                                 size_t length);
+#define EFX_MCDI_NVRAM_LEN_MAX 128
 extern int efx_mcdi_nvram_erase(struct efx_nic *efx, unsigned int type,
                                 loff_t offset, size_t length);
 extern int efx_mcdi_nvram_update_finish(struct efx_nic *efx,
diff --git a/drivers/net/sfc/mtd.c b/drivers/net/sfc/mtd.c
index 3a464529a46b..407bbaddfea6 100644
--- a/drivers/net/sfc/mtd.c
+++ b/drivers/net/sfc/mtd.c
@@ -23,7 +23,6 @@
 #include "mcdi_pcol.h"
 
 #define EFX_SPI_VERIFY_BUF_LEN 16
-#define EFX_MCDI_CHUNK_LEN 128
 
 struct efx_mtd_partition {
         struct mtd_info mtd;
@@ -428,7 +427,7 @@ static int siena_mtd_read(struct mtd_info *mtd, loff_t start,
         int rc = 0;
 
         while (offset < end) {
-                chunk = min_t(size_t, end - offset, EFX_MCDI_CHUNK_LEN);
+                chunk = min_t(size_t, end - offset, EFX_MCDI_NVRAM_LEN_MAX);
                 rc = efx_mcdi_nvram_read(efx, part->mcdi.nvram_type, offset,
                                          buffer, chunk);
                 if (rc)
@@ -491,7 +490,7 @@ static int siena_mtd_write(struct mtd_info *mtd, loff_t start,
         }
 
         while (offset < end) {
-                chunk = min_t(size_t, end - offset, EFX_MCDI_CHUNK_LEN);
+                chunk = min_t(size_t, end - offset, EFX_MCDI_NVRAM_LEN_MAX);
                 rc = efx_mcdi_nvram_write(efx, part->mcdi.nvram_type, offset,
                                           buffer, chunk);
                 if (rc)