In the TZ Memory Protection Controller, the BLK_MAX register is supposed to return the maximum permitted value of the BLK_IDX register. Our implementation incorrectly returned max+1 (ie the total number of valid index values, since BLK_IDX is zero-based).
Correct this off-by-one error. Since we consistently initialize and use s->blk_max throughout the implementation as the 'size' of the LUT, just adjust the value we return when the guest reads the BLK_MAX register, rather than trying to change the semantics of the s->blk_max internal struct field. Fixes: https://bugs.launchpad.net/qemu/+bug/1806824 Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> --- hw/misc/tz-mpc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/misc/tz-mpc.c b/hw/misc/tz-mpc.c index e0c58ba37ec..946147b1c02 100644 --- a/hw/misc/tz-mpc.c +++ b/hw/misc/tz-mpc.c @@ -150,7 +150,7 @@ static MemTxResult tz_mpc_reg_read(void *opaque, hwaddr addr, r = s->ctrl; break; case A_BLK_MAX: - r = s->blk_max; + r = s->blk_max - 1; break; case A_BLK_CFG: /* We are never in "init in progress state", so this just indicates -- 2.19.2