Logical and physical block sizes in QEMU are limited to 32 KiB.

This appears unnecessary tight, and we've seen bigger block sizes handy
at times.

Lift the limitation up to 2 MiB which appears to be good enough for
everybody, and matches the qcow2 cluster size limit.

Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
---
v4 -> v5:
- split out into separate patch [Philippe]
- as this patch has changed significantly lose Eric's r-b

 hw/core/qdev-properties.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index fd945ce77f..01589e1ad6 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -1206,9 +1206,12 @@ const PropertyInfo qdev_prop_size = {
 /* lower limit is sector size */
 #define MIN_BLOCK_SIZE          512
 #define MIN_BLOCK_SIZE_STR      "512 B"
-/* upper limit is the max power of 2 that fits in uint16_t */
-#define MAX_BLOCK_SIZE          (32 * KiB)
-#define MAX_BLOCK_SIZE_STR      "32 KiB"
+/*
+ * upper limit is arbitrary, 2 MiB looks sufficient for all sensible uses, and
+ * matches qcow2 cluster size limit
+ */
+#define MAX_BLOCK_SIZE          (2 * MiB)
+#define MAX_BLOCK_SIZE_STR      "2 MiB"
 
 static void set_blocksize(Object *obj, Visitor *v, const char *name,
                           void *opaque, Error **errp)
-- 
2.26.2