[PATCH-for-10.0 3/3] hw/char/riscv_htif: Clarify MemoryRegionOps expect 32-bit accesses

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Looking at htif_mm_ops[] read/write handlers, we notice they
expect 32-bit values to accumulate into to the 'fromhost' and
'tohost' 64-bit variables. Explicit by setting the .impl
min/max fields.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
Notes

1/ these variables belong to HTIFState but are declared statically!

  static uint64_t fromhost_addr, tohost_addr, begin_sig_addr, end_sig_addr;

2/ I believe a 64-bit implementation would simplify the logic.

3/ This is a non-QOM device model!

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/char/riscv_htif.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c
index 3f84d8d6738..db69b5e3ca7 100644
--- a/hw/char/riscv_htif.c
+++ b/hw/char/riscv_htif.c
@@ -325,6 +325,10 @@ static const MemoryRegionOps htif_mm_ops = {
     .read = htif_mm_read,
     .write = htif_mm_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
 };
 
 HTIFState *htif_mm_init(MemoryRegion *address_space, Chardev *chr,
-- 
2.45.2