Re: [PATCH 2/3] m25p80: Improve command handling for Jedec and unsupported commands

[Philippe Mathieu-Daudé]

Hi Guenter,

On 2/3/20 7:09 PM, Guenter Roeck wrote:
Always report 6 bytes of JEDEC data. Fill remaining data with 0.
For unsupported commands, keep sending a value of 0 until the chip
is deselected.

Two changes, I'd rather see 2 patches. If you happen to respin they are 
welcome. As the split is trivial maybe a block maintainer is OK to do 
it. Regardless the outcome:
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>


Both changes avoid attempts to decode random commands. Up to now this
happened if the reported Jedec data was shorter than 6 bytes but the
host read 6 bytes, and with all unsupported commands.

Signed-off-by: Guenter Roeck <li...@roeck-us.net>
---
  hw/block/m25p80.c | 10 +++++++++-
  1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c
index 63e050d7d3..aca75edcc1 100644
--- a/hw/block/m25p80.c
+++ b/hw/block/m25p80.c
@@ -1040,8 +1040,11 @@ static void decode_new_cmd(Flash *s, uint32_t value)
          for (i = 0; i < s->pi->id_len; i++) {
              s->data[i] = s->pi->id[i];
          }
+        for (; i < SPI_NOR_MAX_ID_LEN; i++) {
+            s->data[i] = 0;
+        }
  
-        s->len = s->pi->id_len;
+        s->len = SPI_NOR_MAX_ID_LEN;
          s->pos = 0;
          s->state = STATE_READING_DATA;
          break;
@@ -1158,6 +1161,11 @@ static void decode_new_cmd(Flash *s, uint32_t value)
          s->quad_enable = false;
          break;
      default:
+        s->pos = 0;
+        s->len = 1;
+        s->state = STATE_READING_DATA;
+        s->data_read_loop = true;
+        s->data[0] = 0;
          qemu_log_mask(LOG_GUEST_ERROR, "M25P80: Unknown cmd %x\n", value);
          break;
      }