hw/char/riscv_htif: Fix printing of console characters on big endian hosts

The character that should be printed is stored in the 64 bit "payload"
variable. The code currently tries to print it by taking the address
of the variable and passing this pointer to qemu_chr_fe_write(). However,
this only works on little endian hosts where the least significant bits
are stored on the lowest address. To do this in a portable way, we have
to store the value in an uint8_t variable instead.

Fixes: 5033606780 ("RISC-V HTIF Console")
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230721094720.902454-2-thuth@redhat.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit c255946e3d)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: edit to compensate for v7.2.0-805-g753ae97abc and v7.2.0-808-gdadee9e3ce)

hw/char/riscv_htif.c

@@ -146,7 +146,8 @@ static void htif_handle_tohost_write(HTIFState *htifstate, uint64_t val_written)
             htifstate->env->mtohost = 0; /* clear to indicate we read */
             return;
         } else if (cmd == 0x1) {
-            qemu_chr_fe_write(&htifstate->chr, (uint8_t *)&payload, 1);
+            uint8_t ch = (uint8_t)payload;
+            qemu_chr_fe_write(&htifstate->chr, &ch, 1);
             resp = 0x100 | (uint8_t)payload;
         } else {
             qemu_log("HTIF device %d: unknown command\n", device);