Peter Maydell <peter.mayd...@linaro.org> writes: > In commit b88cfee90268cad we defined masks for the IBRD and FBRD > integer and fractional baud rate divider registers, to prevent the > guest from writing invalid values which could cause division-by-zero. > Unfortunately we got the mask values the wrong way around: the FBRD > register is six bits and the IBRD register is 16 bits, not > vice-versa. > > You would only run into this bug if you programmed the UART to a baud > rate of less than 9600, because for 9600 baud and above the IBRD > value will fit into 6 bits, as per the table in > > https://developer.arm.com/documentation/ddi0183/g/programmers-model/register-descriptions/fractional-baud-rate-register--uartfbrd > > The only visible effects would be that the value read back from > the register by the guest would be truncated, and we would > print an incorrect baud rate in the debug logs. > > Cc: qemu-sta...@nongnu.org > Fixes: b88cfee90268 ("hw/char/pl011: Avoid division-by-zero in > pl011_get_baudrate()") > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2610 > Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Alex Bennée <alex.ben...@linaro.org> -- Alex Bennée Virtualisation Tech Lead @ Linaro
