[PATCH] hw/block/pflash_cfi01: Limit maximum flash size to 256 MiB

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

As of this commit, the biggest CFI01 NOR flash documented is
the Micron PC28F00BP33EF. Its size is 2 GiB (256 MiB).

Actually this "2Gb device employs a virtual chip enable feature,
which combines two 1Gb die with a common chip enable".

Since we do not want to model unrealistic hardware, cap the
current model to this maximum. At least we have a datasheet
to refer.

If a bigger flash is provided, the user get this warning:

  qemu-system-aarch64: Initialization of device cfi.pflash01 failed: Maximum supported CFI flash size is 16 MiB.

Note, the sbsa-ref ARM machine introduced in commit 64580903c2b
already uses a pair of 256 MiB flash devices.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/block/pflash_cfi01.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
index 11922c0f96..40f145dde7 100644
--- a/hw/block/pflash_cfi01.c
+++ b/hw/block/pflash_cfi01.c
@@ -37,6 +37,8 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/units.h"
+#include "qemu/cutils.h"
 #include "hw/block/block.h"
 #include "hw/block/flash.h"
 #include "hw/qdev-properties.h"
@@ -68,6 +70,8 @@ do {                                                        \
 #define PFLASH_BE          0
 #define PFLASH_SECURE      1
 
+#define PFLASH_SIZE_MAX     (256 * MiB) /* Micron PC28F00BP33EF */
+
 struct PFlashCFI01 {
     /*< private >*/
     SysBusDevice parent_obj;
@@ -717,6 +721,12 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
     }
 
     total_len = pfl->sector_len * pfl->nb_blocs;
+    if (total_len > PFLASH_SIZE_MAX) {
+        char *maxsz = size_to_str(PFLASH_SIZE_MAX);
+        error_setg(errp, "Maximum supported CFI flash size is %s.", maxsz);
+        g_free(maxsz);
+        return;
+    }
 
     /* These are only used to expose the parameters of each device
      * in the cfi_table[].
-- 
2.21.3